# TPA3118 60W Power Amp Module



## falzhobel

Hi guys,

I just want to clarify what's included in the "new" TPA3118 60W Power Amp Module. Is it only for the PCB ? Will it be possible to have it with the SMD soldered ? 

Thanks ! 

GUP


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## zgrav

Same question here.  Can this board be ordered with the SMD chip already soldered in place?  --- NVM, this appears to be a board already populated with the chip and components, right?  Looks like the same item and similar versions are availbable from Amazon:  https://www.amazon.com/s?k=tPA3118+60W+Power+Amp+Module&ref=nb_sb_noss


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## Robert

The TPA3118 module comes exactly like you see it in the pic, all components are already installed.   Yes, you can get the exact same thing from Amazon, eBay, etc.    It's offered here as a convenience.  (Just be sure the pinout and dimensions are the same if you plan to use it on one of the upcoming projects)

This isn't intended to be used as-is, it will be treated like a large IC and be soldered to a larger interface board.

You could of course wire it up yourself, but it doesn't have any sort of volume control or preamp.    The upcoming interface board will take care of that.


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## Nostradoomus

That’s awesome. I hope the preamp I messaged you about is part of this.


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## bretvh

Ok, I'm super interested in this whole power amp mystery. Please tell me it's going to be a pedalboard-mounted power amp project.


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## Robert

bretvh said:


> Please tell me it's going to be a pedalboard-mounted power amp project.



It's going to be a pedalboard-mounted power amp project.


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## temol

Will it be powered by 24V (max allowed for the module)? Is there any 9V circuitry included?

T


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## phi1

According to the amazon pages for this (I think it's the same), you can power it with anywhere from 8 to 24V DC.  Lower voltage will of course mean lower output power.  I'm thinking of a crude calculation where P=IV, and I=V/R, so P=V^2/R.  So the relationship between voltage and power is not linear, since the voltage factor is squared.  So, if 24v gives 60W, 9v should give about 8.4W.  The actual math is probably much more involved, but I think the relationship still roughly holds.  Please chime in anyone else if this seems at all accurate or not!  

Also, I saw on one amazon page that the 60W at 24v DC is in a 2ohm speaker.  So 24V into a 4 ohm speaker would be 30W (linear relationship between R and P).  So, 9V into an 8ohm speaker would be closer to 2W (again don't quote me, just trying to make a rough estimate).

I saw that the recommended current for the power supply is 3A.  This will be too high to use a charge pump to boost 9V to a higher voltage.  It also means you'll probably need to run this of a dedicated power source (most pedal power blocks or 1spot don't offer up to 3A).  So, since it requires a separate power source anyway, might as well get one that operates at a higher voltage.

@PedalPCB am I making sense?!


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## Robert

I haven't worked all the math at this point, but no, this would not be powered by a charge pump.

I've powered it from a 9V 1-Spot (1.7A max) plugged into my 4 ohm Fender Twin cab and it would absolutely take your head off.    I couldn't comfortably bring the volume above 1/3.    Higher ohm cabs would benefit from a 24V supply.

The first revision will be a basic "clean" power amp that would require (or at least benefit from) a preamp in front, basically a power amp for the end of your pedal chain.     As we move forward I do plan to work on complete "amp in a pedal" projects that include everything, possibly even some multi-channel projects.     There's even been discussion of some tube-based preamps.



temol said:


> Will it be powered by 24V (max allowed for the module)? Is there any 9V circuitry included?



In the cases where 9V (or lower) circuitry is required we'll use a regulator so everything plays nicely together.


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## Tremster

Mhhhh.
I intend to use this with my 8" 20 Watt speaker, Champ cabinet.
Will that be safe? Or would I need a more powerful speaker?


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## temol

I'm interested if there is another device in the future "power amp" that requires 9V supply. To get the maximum out of the module it's necessary to have 24V (and low impedance speakers), but many (if not most) devices are 9V friendly. No problem when you have separate units. But in case of "all in one box" you have to drop some V for the 9V circuits. Voltage regulator - too much heat I suppose. Step down converter? Other ideas?

ps. 
24V supply, 8 ohm load  - 1.33A, 44.8V p/p, 15.6V RMS before it starts to clip. This gives around 30W. 

T


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## Gordo

Watching and waiting...


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## falzhobel

A "Pedal Amp" will be a very nice Backup to an old un-trustable amp ^^


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## mywmyw

very excited for this. a pedal power amp project with eq, or something like the quilter tri-q would be indispensable


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## MikeR

Looking forward to this as well.  I have a spare TPA3118 module from when I built a pedal-based amp a year ago.  It was very basic with just a single volume control and an on-off switch.  Used a 19.5V, 3A laptop power supply into an 8 ohm speaker.  Plenty loud enough for a bedroom practice or coffeehouse amp.  I used a preamp pedal in front of it which is sorely needs.  Really interested in trying it with a PedalPCB board.


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## zgrav

Any additional heat sinks needed for this small amp?  Have not seen any mention of needing a heat sink in what I have found on the internet.


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## zgrav

I'm looking forward to seeing these boards to use with the module.  I have one on the modules now I am going to put into an enclosure along with a 9v  regulator that feeds a couple of power jacks so a laptop battery at 20+ v can run the power amp and a few pedals.


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## Robert

Nope, I don't think there's any need for a heat sink.


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## zgrav

Robert said:


> Nope, I don't think there's any need for a heat sink.



I think you're right.  Seems much more efficient than the Tiny Giant 20 watt amp where most designs use the case as the heat sink.


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## zgrav

Not to rush the design process, but I am curious when are we going to get a glimpse of your PCB to work with this power amp module?  Are you looking at a way to attache the power module to the new PCB?  Or will the two boards coexist inside the case?


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## SuperReverbMan

I bought two of the TPA3118 modules anticipating the next phase of this project. Patiently waiting...


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## Vildhjuggah

Whenever this interface board comes out maybe using this case (painted or something) and a friedman be-od deluxe board or maybe a bigger one to make a little amp head 






						YaeCCC Rectangle Project Enclosure Case Electric Junction Box Blue 170mm x 130mm x 80mm / 6.4" x 4.3" x 2.7" - - Amazon.com
					

YaeCCC Rectangle Project Enclosure Case Electric Junction Box Blue 170mm x 130mm x 80mm / 6.4" x 4.3" x 2.7" - - Amazon.com



					www.amazon.com


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## Robert

zgrav said:


> Not to rush the design process, but I am curious when are we going to get a glimpse of your PCB to work with this power amp module?  Are you looking at a way to attache the power module to the new PCB?  Or will the two boards coexist inside the case?



Development has been set back a little since the PCB factories have all been shut down for the holiday (and now coronavirus).

The power amp module will attach to the interface board with pinheaders.

This was the first prototype, mainly just to ensure the dimensions were correct for the module to attach.


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## zgrav

Thanks for the update.  Very cool idea.  Looks like a volume control on the other side.  Do you also have a toggle for the mute function?


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## Robert

zgrav said:


> Thanks for the update.  Very cool idea.  Looks like a volume control on the other side.  Do you also have a toggle for the mute function?



Yes, this was just a basic input buffer with master volume control.    

I did not add a toggle for the mute function, but as you can see I left the pads open on the TPA module....  I was considering wiring that to a footswitch.

One critical detail is the isolated 1/4" jacks...  They need to be genuine Neutrik brand, the Chinese knockoffs are slightly wider and won't fit between the screw supports at the top.      You can, however, sand or file down the plastic corners and they'll fit. (which is what I've done here)

The DC jack _might_ be more sensible placed on the side, despite how much I am opposed to that....   I'm sure quite a few people are going to want to use a 24V supply (with relatively high current).   Those are generally fatter plugs so the jack might not fit at the top.


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## zgrav

FWIW, I put this in a 1590BB case without an additional input buffer, using a regular input jack and an isolated output jack and top-mounted power jack.  I used a DPDT on-on-on toggle switch for power and mute, to be power off in the first position, second position "Standby" with power on (LED comes on with the power) and muted, and third position "On"  with power + unmuted.  I am pondering whether I can wire the power and mute functions to work with a bi-color LED to get different colors for Standby and ON.

I wanted to run this box off of a 20 volt laptop power supply so I also added a TO-220 9-volt regulator to power a couple of side-mounted jacks for pedals.  I have the EMU amp box leading into it, and it is a good combination.


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## Mike McLane

I'd love to toss a good solid state amp in the bottom of a cab loaded with REAL guitar speakers, put a preamp pedal (like a Kingsley) together with my PPCB builds and head out the door.  Do you anticipate this product to serve that end?


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## zgrav

I think you will see a few different builds with the module.  What you use to power it will have a lot to do with the results you get, and it will give you something good even at 9 volts (although probably drawing more current than most effects).  If you use a 20 volt laptop charger and have a 4-ohm or an 8-ohm load, it is impressive.  It puts out painful sound levels in a pair of AR speakers with 10-inch woofers that are wired in parallel for 4-ohm operation.   It should have no trouble driving a 2 x 12 cab (and probably a 4 x 12 cab) for a small venue, but I have not tried it.

The module will handle higher input levels than a bypassed guitar signal, so I added in a small buffer/booster board on my box to set the floor for a bypassed guitar signal at a higher level.  Something like this  --  http://tagboardeffects.blogspot.com/2013/01/electro-harmonix-lpb1-with-trimmer.html


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## Mike McLane

I'm REALLY anxious to see something come from this.  Any thought given to bass players who may need something with higher output?  I play bass quite frequently and something for a small powered bass cab (200W +\-) would be equally appreciated.


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## Mike McLane

Any headway on the TPA3118 front?!?!?!?!


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## stevel

While I will certainly go for a complete project when available, I have ordered one of the TPA3118 boards now to play with. I see that it needs a preamp to function correctly. Would my Line 6 HX Stomp qualify? Or do I need something else? Like what? I am willing to build something if needed, but I also have various boost pedals (SHO, AMZ MOSFET Booster, Emerson Paramount) and since I saw someone mention the LPB1 here, I thought maybe one of those would do the job. Please let me know what you think.


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## phi1

I think I’m this case “preamp” refers to a tone shaping circuit, since electric guitar amps have a lot of tone shaping (eq and/or distortion), and this amp module is just flat, so your plain guitar will sound thin and sterile.

I don’t think a boost will be necessary volume wise, just look for tone shaping, so maybe like an Emu, or Son of Ben maybe with a cab sim too.  I haven’t tried any of these, just going by what folks have said.


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## stevel

phi1 said:


> I think I’m this case “preamp” refers to a tone shaping circuit, since electric guitar amps have a lot of tone shaping (eq and/or distortion), and this amp module is just flat, so your plain guitar will sound thin and sterile.
> 
> I don’t think a boost will be necessary volume wise, just look for tone shaping, so maybe like an Emu, or Son of Ben maybe with a cab sim too.  I haven’t tried any of these, just going by what folks have said.



If all it needs is tone shaping, then running my HX Stomp into it should be fine. But I also read some people saying that there was an impedance issue, and that running a buffer / preamp was the solution. Not being an engineer, that is above my pay grade.


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## bretvh

I built one of those boards up into an enclosure and didn't really notice any impedance issues. It is very flat, EQ-wise, but even running our ol Tech21 Sansamp through it made a huge difference. The Fender settings sounded really good! Note that for optimum volume, you'll want the highest power supply it's rated for. I think I did a 24v one, but I'd have to check to confirm that. You also will get the most output going into a 4ohm speaker. I ran mine into a 16 ohm, and while it was loud, it was not really "keeping up with a drummer" loud. I imaging going into an 8 or 4 ohm would change the game quite a bit. But, for comparison, my wife's Princeton Reverb RI is much louder than this thing going into a 16ohm speaker.


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## bretvh

BTW, in case you haven't found a schematic, I based mine off of this one: 

https://i.redd.it/nwofw4ve4g921.jpg

Note that I omitted the 4700u cap. I tried with and without and didn't notice much of a difference in the noise floor. ymmv.


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## stevel

bretvh said:


> I built one of those boards up into an enclosure and didn't really notice any impedance issues. It is very flat, EQ-wise, but even running our ol Tech21 Sansamp through it made a huge difference. The Fender settings sounded really good! Note that for optimum volume, you'll want the highest power supply it's rated for. I think I did a 24v one, but I'd have to check to confirm that. You also will get the most output going into a 4ohm speaker. I ran mine into a 16 ohm, and while it was loud, it was not really "keeping up with a drummer" loud. I imaging going into an 8 or 4 ohm would change the game quite a bit. But, for comparison, my wife's Princeton Reverb RI is much louder than this thing going into a 16ohm speaker.



Thanks for the details on your experience. So if the SansAmp made it sound good, I imagine my HX Stomp with amp (and maybe with or without) cab modeling should sound pretty good. I will report back once I have it in hand and set up.

One more thing -- is the isolated ground on the output jack the only trick I need to know?


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## bretvh

stevel said:


> Thanks for the details on your experience. So if the SansAmp made it sound good, I imagine my HX Stomp with amp (and maybe with or without) cab modeling should sound pretty good. I will report back once I have it in hand and set up.
> 
> One more thing -- is the isolated ground on the output jack the only trick I need to know?



The only other thing that comes to mind is if you get the 24v, 3amp power supply, make sure all of your components (ac inlet especially) are rated for that much current. I think I went with some metal 2.1mm, center positive metal ones that fit my power supply, I believe.


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## stevel

bretvh said:


> BTW, in case you haven't found a schematic, I based mine off of this one:
> 
> https://i.redd.it/nwofw4ve4g921.jpg
> 
> Note that I omitted the 4700u cap. I tried with and without and didn't notice much of a difference in the noise floor. ymmv.



You read my mind - than you so much for sending that link. I assume the diode is simply to prevent reverse DC, and as you mentioned the electrolytic cap is probably just some additional filtering (which may not be needed). And the inout cap? Block possible DC on the input? that's probably optional as well, but I can afford to include it 

BTW - doesn't 4700uF seem like a crazy high value to you?


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## bretvh

stevel said:


> You read my mind - than you so much for sending that link. I assume the diode is simply to prevent reverse DC, and as you mentioned the electrolytic cap is probably just some additional filtering (which may not be needed). And the inout cap? Block possible DC on the input? that's probably optional as well, but I can afford to include it
> 
> BTW - doesn't 4700uF seem like a crazy high value to you?



Yeah, in the forum post the person who designed that circuit was talking about filtering out AC. And yeah, I ordered some of those caps thinking I'd use the and they are gigantic!


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## stevel

bretvh said:


> BTW, in case you haven't found a schematic, I based mine off of this one:
> 
> https://i.redd.it/nwofw4ve4g921.jpg
> 
> Note that I omitted the 4700u cap. I tried with and without and didn't notice much of a difference in the noise floor. ymmv.




I just built mine up (except for the power plug). I am a bit confused about the DC power, as the schematic you linked me to shows the negative side of the DC supply going through the cap to the positive side, with no path to ground. And, you mentioned that you omitted the 4700uF cap. So, how exactly did you wire up the DC plug. Diode goes to the positive power on the board, that part is clear. But what about negative from the DC plug - where does it go? To the chassis (perhaps by way of the input jack ground lug)?

Also, does heat become an issue? Should I drill some ventilation holes in this box, or will it be OK as-is?

Here are some photos of mine so far. I'd love to see yours as well.







I may add a power switch at some point, but I want to get it working first 

Thanks for your help.
Steve


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## bretvh

Yeah, I just ran the ground to the board ground and the input jack, I believe. I have not noticed any heat issues, but I haven't pushed mine very hard or used it a ton. And I've only run it into a 16ohm cab so far. Here is a pic of mine, but it's really messy, so apologies in advance. I kind of threw it into this old rotisserie motor housing I've had laying around forever and it really was not a good fit or placement so I just crammed everything in there as a temporary measure. I'll likely rehouse it some day down the  line!


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## Elijah-Baley

Cool!
I took of this power amp from the cart in my last order because I have really nothing to power it up.
Unfortunately, I don't have any PSU laptop, it seem hard to be answered but, what PSU I could buy for it.


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## stevel

I completed the TPA3118 based amp today. I found another version of the schematic, and it properly showed how the DC plug should be configured. The one linked above was cut out of the one I attached here (which is the stereo version), but in the mono schematic, the negative side of the DC plug was not connected to a ground (and it should be). I suspected that was an issue, and wanted to verify before completing the project, which this stereo schematic did for me. I also discovered that the pot is wired backwards in the diagram. It got louder to the left and quiet to the right. So I've reversed it in my build. And finally, I also left out the 4700uF cap. The largest I have on hand is 1000uF, and could tack it in, but not sure I need it yet. We'll see.

I am using a laptop power supply for a laptop I just disposed of yesterday. The PS output is 19v at 3.4A center positive. I put together a polarity switching adapter since the amp is setup center negative like most of our other devices.

As expected, it sounds pretty bad without something feeding it. But I certainly knew to expect that. But, when fed by my Line 6 POD GO, it sounded pretty good. I only just finished it, and only did a brief test so far. I will have to play with it some more to see if it is fine as is, or perhaps I will set the global EQ in the modeler to tweak things a bit. Funny thing - first time I played through it, it sounded bright and harsh and terrible. Then I remembered that I was playing through a real guitar cabinet, and had to disable the cab simulation in the GO 

How loud is it you ask? (I know, you didn't actually ask).

Well, like all solid state wattage specs, it is VERY misleading. Direct from the guitar (no preamp), it is not loud at all - wouldn't even wake a sleeping child. But driven by the POD GO, it reaches levels that might actually be loud enough for my basement band rehearsals. I would imagine that the same would be true with a variety of other preamp types as well (buffers, boosts, etc) in front of this little amp. Frankly, for me, the volume pot on the amp will never be set much below max unless I am playing at home and want to keep things pretty quiet. But it is loud enough for what it is for sure. 

Just for the hell of it, I've ordered and will try the TPA3116 (100 watts, "yea right") to see if it is noticeably louder. It might suit me better. or it might be more of the same.

Thanks for pointing me to the original schematic - it helped a lot in getting to this point.


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## bretvh

Elijah-Baley said:


> Cool!
> I took of this power amp from the cart in my last order because I have really nothing to power it up.
> Unfortunately, I don't have any PSU laptop, it seem hard to be answered but, what PSU I could buy for it.


I bought this one and it’s worked out well so far:

SUPERNIGHT 24V Power Supply, AC 100-240V to DC 24V 3A Power Adapter Transformer Converter for LED Strip Light, CCTV, Router, ADSL https://www.amazon.com/dp/B0759JPVVP/ref=cm_sw_r_cp_api_i_a7PZEb29TYMTB


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## stevel

I've been using the little amp based on the TPA3118 mono board with my modeler, and it sounds pretty good, and it is pretty loud. I am using a 24V supply, into an 8ohm 1x12 cabinet. But it is certainly not as loud as 60 watts would suggest. Now I know very well that SS watts and tube watts can't be compared. But still, the volume is not blowing me away - I think my 12 watt Princeton is louder. I also bought a TPA3116 mono board (100 watts), and built the same amp circuit using that board. And it is also not super loud. I find I am putting these amps on about 3 o'clock (75%) to get them to be fairly loud. 

So here is my question -- maybe these power amps really need a preamp to reach their full potential -- any thoughts on that? If you think that is the case, what preamp board would you suggest?


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## bretvh

I noticed a big bump in volume when I ran my Sansamp into it. Not enough to push it into "playing with a drummer" territory, but a noticable difference for sure.


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## stevel

bretvh said:


> I noticed a big bump in volume when I ran my Sansamp into it. Not enough to push it into "playing with a drummer" territory, but a noticable difference for sure.



Yea, for sure. Same here with my POD GO or HX Stomp. Although, if I put the amp on 10, it might be able to hang in with a drummer. It's hard to tell at home in isolation. But it almost seems like I shouldn't have bothered to install the volume pot


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## Warmdrive

Robert said:


> I haven't worked all the math at this point, but no, this would not be powered by a charge pump.
> 
> I've powered it from a 9V 1-Spot (1.7A max) plugged into my 4 ohm Fender Twin cab and it would absolutely take your head off.    I couldn't comfortably bring the volume above 1/3.    Higher ohm cabs would benefit from a 24V supply.
> 
> The first revision will be a basic "clean" power amp that would require (or at least benefit from) a preamp in front, basically a power amp for the end of your pedal chain.     As we move forward I do plan to work on complete "amp in a pedal" projects that include everything, possibly even some multi-channel projects.     There's even been discussion of some tube-based preamps.
> 
> 
> 
> In the cases where 9V (or lower) circuitry is required we'll use a regulator so everything plays nicely together.


I have seen and heard the Joyo American sound and the Tech 21 Blonde used in front of this amp module with really good results.
I would really like to see a Pedal PCB version of the American sound and the California sound in a 125B six knob format to use with this amp module.
Thank you for all the work and effort to bring great projects to life.


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## stevel

I think my next test will be to run my modeler into a separate boost pedal and then on into the amp. I want to see if it has enough headroom to take a bigger signal without falling apart. If so, I may try to mod one of the boxes I’ve already built up to include the booster. My thought is to set the boost level with a board mounted trim pot to the highest level possible before breakup. Maybe I’ll have a little time to experiment on Sunday. I’d really love to be able to use this with the band either for rehearsals or as a backup amp at a gig. If it gets loud enough, it could even be the primary amp at a gig.

BTW - the 100 watt TPA3116 was not significantly louder than the TPA3118, which is to be expected. But perhaps it will have more headroom than the 3118....


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## stevel

stevel said:


> I think my next test will be to run my modeler into a separate boost pedal and then on into the amp. I want to see if it has enough headroom to take a bigger signal without falling apart. If so, I may try to mod one of the boxes I’ve already built up to include the booster. My thought is to set the boost level with a board mounted trim pot to the highest level possible before breakup. Maybe I’ll have a little time to experiment on Sunday. I’d really love to be able to use this with the band either for rehearsals or as a backup amp at a gig. If it gets loud enough, it could even be the primary amp at a gig.
> 
> BTW - the 100 watt TPA3116 was not significantly louder than the TPA3118, which is to be expected. But perhaps it will have more headroom than the 3118....




Well, I found the time to do a quick experiment today. I have a cheap Donner DI box, which includes a -20db / 0db / +20db switch. So I played through my POD Go into the DI into the amp, and I tried the DI in the +20db position. Holy crap!  Placing that +20db boost in front of the amp made it super loud (well of course it did, 20db is a lot). With the volume pot on the amp set below 75% on the amp, the tone was mostly the same as when the DI was on 0db, but louder. From 75% up to full blast on the amp, the sound got thicker and a bit more driven sounding, which is not really a surprise. While pure transparent tones all the way up would have been better for my needs, I can live with this performance. By that point it was so loud, I didn't need anymore anyway. 

So I could just front end the amp with this DI since I already own it, or I could try building a tiny clean boost right into the amp enclosure, perhaps with something less than 20db of boost. Ideally, it would be as transparent as the boost in the DI. But that might imply a more complex circuit, and I really want to build something tiny enough to go onboard between the input jack and the amp pcb. Of course, doing it outboard is MUCH simpler as I can power it with 9v even though the amp is powered with 24v. Onbaord implies dropping the voltage to the boost, AND if I ever power this amp with a 9v supply, the boost won't get enough power unless I make that dropping string switchable. 

If anybody has a suggestion on a boost circuit that would be high headroom (not overdriven from my modeler), VERY transparent, really tiny, and maybe boost by about 9 to 12db, please let me know. And if you have any cool ideas on the voltage drop part of this, fill me in on that as well.

More to come.


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## stevel

stevel said:


> Well, I found the time to do a quick experiment today. I have a cheap Donner DI box, which includes a -20db / 0db / +20db switch. So I played through my POD Go into the DI into the amp, and I tried the DI in the +20db position. Holy crap!  Placing that +20db boost in front of the amp made it super loud (well of course it did, 20db is a lot). With the volume pot on the amp set below 75% on the amp, the tone was mostly the same as when the DI was on 0db, but louder. From 75% up to full blast on the amp, the sound got thicker and a bit more driven sounding, which is not really a surprise. While pure transparent tones all the way up would have been better for my needs, I can live with this performance. By that point it was so loud, I didn't need anymore anyway.
> 
> So I could just front end the amp with this DI since I already own it, or I could try building a tiny clean boost right into the amp enclosure, perhaps with something less than 20db of boost. Ideally, it would be as transparent as the boost in the DI. But that might imply a more complex circuit, and I really want to build something tiny enough to go onboard between the input jack and the amp pcb. Of course, doing it outboard is MUCH simpler as I can power it with 9v even though the amp is powered with 24v. Onbaord implies dropping the voltage to the boost, AND if I ever power this amp with a 9v supply, the boost won't get enough power unless I make that dropping string switchable.
> 
> If anybody has a suggestion on a boost circuit that would be high headroom (not overdriven from my modeler), VERY transparent, really tiny, and maybe boost by about 9 to 12db, please let me know. And if you have any cool ideas on the voltage drop part of this, fill me in on that as well.
> 
> More to come.



I also tried my old trusty AMZ MOSFET booster in front of the TPA3118 amp, and found it behaved quite similarly. And its board is tiny. So I built up a board to install inside of the amp enclosure. I had to order a couple of parts to complete the install, so it will take a while before I can report any results and show any photos. This one will end up being a prototype as grafting on the AMZ board may not be so pretty. But pulling it all apart and rebuilding it neater will be worth it if I like the results. I don't expect to have to drill any holes, which is a good thing.

I am also going to experiment with a 50k linear pot instead of the 50k audio pot in their right now. I think if the sweep of the pot wasn't so weighted to the end of the rotation, I'd like it better. Maybe. Easily reversed if I hate it.

I expect to use this amp for the first time on Tuesday night at a band rehearsal. I usually use a VOX MV50 Clean into a 1x12 open back cabinet loaded with an 8ohm speaker (if I remember correctly), with all amp modeling turned off. This time, I will use the TPA3118 amp into that same cabinet with the amp modeling turned on (cab modeling turned off). If it is able to achieve similar volume levels without the AMZ board installed, it will be a YIPEE moment.


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## stevel

Band rehearsal went really well with this little amp driving my 1x12. Amp was set on about 1 o'clock, and I had no problem keeping up with the 2nd guitar, bass and drums. Room to spare on the POD Go's volume control as well. I've built 3 of these now - 2 with the TPA3118 (60 watts), and 1 with the TPA3116 (100 watts). I plan to install the AMZ MOSFET Booster board into the TPA3116 version, maybe on Sunday. I have another enclosure on the way so that I can build another of the TPA3116 versions as well. I like to have spares especially at gigs. And these spares will fit in my backpack. Awesome stuff.


----------



## stevel

Question regarding Class D amps:
We all know that 100 tube watts is MUCH louder than 100 solid state watts. So does that mean that my speaker can handle MORE Class D watts safely than it can handle tube watts? For example, would my 100 watt 12" speaker be able to handle say 150 or even 200 Class D watts?


----------



## Nostradoomus

No, a watt is a watt. Tubes are able to push more clean volume than a solid state due to a variety of factors (Total Harmonic Distortion etc) but don’t use a 200w amp with a 100w speaker.


----------



## kg250zw7

Any update on when this will be available?


----------



## c.h.u.d

I put one of these together and have been running it into a 2x12 at 4 or 16 ohms with a Joyo British Sound in the front. I am getting some great sounds out of the setup but I am finding the joyo doesn’t play so well with other od/distortion pedals in this context.

I was considering putting together a ROG tonemender but was curious if anyone could recommend a cleanish preamp/eq that might work for me. 

Also here is an obligatory gutshot. I could have planned the cap location better but such is life.


----------



## zgrav

I built the ROG Umble and use that in front of a small solid state amplifier.  http://www.runoffgroove.com/umble.html


----------



## phi1

The ROG tone mender is designed to emulate the passive tone stack in fender, box, or Marshall amp. The tone will effectively have a mid scoop, except when bass and treble are both at minimum. It can’t boost the mids at all.

Many people like it though. I breadboarded the circuit at one point and found it generally too bright for my taste (which makes sense, treble sounds boosted relative to mids except when treble is at minimum).


----------



## stevel

Given the schematic I posted earlier in this thread, how would I prevent the loud pop that occurs when powering on the amp? I've been turning down the volume prior to hitting the power switch, but that is getting old. I know there is a mute on the board, but I'd rather not add a "standby"  switch. I am hoping that by placing a resistor to ground from somewhere in the circuit would bleed the transient off, or some other solution like that.


----------



## temol

stevel - maybe something like this? Or google for turn-on delay / speaker protection / speaker soft start circuits.


----------



## Mike McLane

Anybody have a minimalist layout of what would be required to get one of these guys working?  I've seen pics with added circuitry for volume, EQ or some kind of buffering/preamplification, etc. but could I get away with wiring an outboard preamp and appropriate power supply directly into the TPA3118 and wire it directly to speakers?


----------



## stevel

Mike McLane said:


> Anybody have a minimalist layout of what would be required to get one of these guys working?  I've seen pics with added circuitry for volume, EQ or some kind of buffering/preamplification, etc. but could I get away with wiring an outboard preamp and appropriate power supply directly into the TPA3118 and wire it directly to speakers?



I use these boards in a small pedal sized enclosure with just an input jack, an output jack, a power jack, a power switch, an LED and a volume control. I am attaching the diagram I followed (I only built half of this 2 channel diagram of course). I've used this same diagram with the 30, 60 and 100 versions of these boards. There is one diode and one capacitor off-board in this configuration (I didn't use the electrolytic cap - it really wasn't needed). I play a Line 6 HX Stomp or POD Go or a Strymon Iridium directly into this amp, and then connect it up to my 1x12 guitar cabinet. I hope this helps.


----------



## Mike McLane

EXACTLY what I'm looking for!!  Thanks!!  How do you like working with the HX stomp?  I have one that I've been using to run my acoustic thru. . .works great, IR host and all of the FX I need in one very portable box.  May be doing some electric gigs and have perused all of the feedback on modelers for live use.  The cork sniffers seem to poo-poo 'em, but there are some good, demanding pro players around here who I have talked to and they have had great results.


----------



## stevel

Mike McLane said:


> EXACTLY what I'm looking for!!  Thanks!!  How do you like working with the HX stomp?  I have one that I've been using to run my acoustic thru. . .works great, IR host and all of the FX I need in one very portable box.  May be doing some electric gigs and have perused all of the feedback on modelers for live use.  The cork sniffers seem to poo-poo 'em, but there are some good, demanding pro players around here who I have talked to and they have had great results.


I love the Stomp. I play mostly electric, but I also have an acoustic IR or two for when I do acoustic stuff. I have a Morningstar MC6 MKII MIDI controller too, which lets me control more Stomp functions since it has just 3 footswitches built in. Very cool stuff. Once you build up one of the amps, post your results


----------



## Mike McLane

Thx!!  I assume that the 3A power diode is a 1N5817?  The mute is just a SPST (on/off) that bridges the connections on the Mute eyelets.  Also, how would the power LED be wired in?


----------



## Mike McLane

From reviewing other schematics it appears that the power LED runs: +9vdc --> LED(A) / LED(K) --> 4K7 resistor --> to GRD.  It appears as though the order of resistor & LED is immaterial.  Pls confirm.


----------



## stevel

Mike McLane said:


> From reviewing other schematics it appears that the power LED runs: +9vdc --> LED(A) / LED(K) --> 4K7 resistor --> to GRD.  It appears as though the order of resistor & LED is immaterial.  Pls confirm.


You can place the resistor either in front of the LED or after it. Either way, it will limit the current flowing through the LED, which is the purpose. I usually put it on the +9V side, and connect the other side of the LED directly to ground.


----------



## stevel

Mike McLane said:


> Thx!!  I assume that the 3A power diode is a 1N5817?  The mute is just a SPST (on/off) that bridges the connections on the Mute eyelets.  Also, how would the power LED be wired in?


I used 1N5408's. The 1N5817, if I am reading the specs correctly is a 1A diode (and Shottky type diode, not that I know what that means).



			http://www.irf.com/product-info/datasheets/data/1n5817.pdf
		




			https://www.mouser.com/datasheet/2/149/1N5408-888344.pdf


----------



## Paradox916

I just got a 1N5402 under the assumption it would be more than enough... but If I burn anything up I’ll let you know🤣.
By the way how is that little amp holding up?


----------



## stevel

Paradox916 said:


> I just got a 1N5402 under the assumption it would be more than enough... but If I burn anything up I’ll let you know🤣.
> By the way how is that little amp holding up?


1N5402 will be fine. The main difference is that it handles up to 200V where the 1N5408 that I used (because I had them on hand) handles up to 1000V. With a 24V power supply, I think you'll be safe


----------



## stevel

I have a couple of Lenovo laptop power supplies that I would like to modify to use with these amp projects. I mainly want to cut off the plug, and solder on a more common 2.1mm x 5.5mm plug oriented the right way.

These power supplies have a ferrite bead very close to the existing plug. Is it needed in this application? If I leave the bead in place, I will have VERY little  room for error when putting the new plug on. I might not even have enough space for the plug jacket. Can I cut off the bead and then solder on my plug or will that basically ruin the power supply for my intended use?


----------



## Mike McLane

Just finished one of these buggers (like the layout pictured above) and I can say it works, but right now that's about all I can say.  I'm powering it with a 19vdc 3.4 amp laptop power supply.  I plugged my HX Stop into it and ran the speaker output to the WGS ET65 in my amp.  Sounded OK, but I quickly discovered that it can be finnicky.  You can push it too hard and it distorts.  Turn up the volume past mid way and it gets very shrill and somewhat garbled.  Since this is a bubble gum & bailing wire sort of build there may be some deficiencies in the build, but I'm guessing that the unit has some limitations in terms of I/O that must be respected in order to get proper performance.  It'll be nice when PPCB puts something out around this board.  Also, FWIW I'm wondering if the 60W board is gonna have enough ummmph to be more than a bedroom product.


----------



## temol

You should keep the input signal level low enough to avoid  amp output signal clipping.  In an ideal world you need a signal generator, oscilloscope and a load. So you have source of a sinewave with a known level, known load (4 or 8 ohm). On the oscilloscope you see the moment when the output sinewave starts to clip. Then you know what's the safe  input signal level range (with clipping free output signal).


----------



## Paradox916

I know the quality consistently had been mentioned with the TPA3118s on several occasions the one I built using this same schematic that has been floating around seems to operate fine without clipping running it off 12v-18v  and pushing a 4x12 cab (that’s all I got for now tell I can come up with a single 12 cab) .is it 60w?... not by a long shot..lol. With a decent preamp it sounds pretty good and with a couple of decent pedals, I think it sounds better that the spider v30 collecting dust in the corner 🤣. But I just don’t see the TPA3118 being anything more than that.  It’s an impressive little piece of tech with its own set of limitations. Just my 2 cents for what it’s worth ( which is about 2 cents not counting for inflation.)


----------



## Mike McLane

I noticed that the Seymour Duncan Powerstage has LED's to signal clipping on both input and output.  Don't know how complicated that is to include in a PPCB design, but it would be nice to have a simple way to "calibrate" input signal levels.   I noticed that when I had it set at what appeared to be a "workable" level it would still distort when I banged out an open E chord.  One simple solution may be just to over-design the unit with much more horsepower such that you could operate it at well under max input and output levels and still get the volume you desire.


----------



## logicist

mywmyw said:


> very excited for this. a pedal power amp project with eq, or something like the quilter tri-q would be indispensable


----------



## megatrav

I just bought 2 TPA3118 boards. I am excited to see where other folks might take this.


----------



## PBWilson1970

Looks like this has potential to go along with my Alembic F2-B style preamp or the Intersound IVP I'm getting ready to assemble. 

On a semi-related topic, are there any Class D modules (ICEpower maybe?) that might work like these for a higher powered power amp? I like the idea of a backup amplifier on my pedalboard or a relatively inexpensive guitar or bass power amp.


----------



## fig

Something like this?









						Home
					

ICEpower 200AC Class D Audio Amplifier Module 1 x 200WThe ICEpower 200AC is a "hanger" amp module powered by the ICEpower DC Bus integrated in the ICEpower 200ASC and 500ASP amp modules. These two amp modules handle up to two additional ICEpower200AC amplifier modules from the integrated power...



					www.parts-express.com


----------



## PBWilson1970

fig said:


> Something like this?
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Home
> 
> 
> ICEpower 200AC Class D Audio Amplifier Module 1 x 200WThe ICEpower 200AC is a "hanger" amp module powered by the ICEpower DC Bus integrated in the ICEpower 200ASC and 500ASP amp modules. These two amp modules handle up to two additional ICEpower200AC amplifier modules from the integrated power...
> 
> 
> 
> www.parts-express.com


I looked at that particular module and the many others on the ICEpower site and unfortunately I'm not knowledgeable enough to determine which one might be work-able for a Class D power amp with a switch and LED, single input, single pot for level, integrated power supply so I could use an IEC connector and one or two output jacks. Sites like this and a few others have allowed me to "paint by numbers" and build dozens of pedals and a few amplifiers without a great deal of knowledge to go it alone.


----------



## Willybomb

Ok, I grabbed a 3116 a while ago, powered it off a secondhand laptop power supply and just had heaps of noise with it.  Didn't work well at all.  Anyway, I recently grabbed a 3118 and hooked it up to the same laptop PS.  Running my Mooer Preamp Live into it gives it heaps of volume and I control the volume using the MPL's master knob.  However, just running one of Effectlayout's JC-120 preamp pcbs into it didn't have much volume at all, even flat out.

I'm guessing I need a booster (LPB1 maybe?) and buffer in front to get the same levels out of it.

Anyway, today I took my ghetto wiring job to band praco and ran it into the studio's 4x12 for two and a half hours.....  No issue keeping up with drums at all.  It's a beast of a little amp....

And a quick vid for proof of concept.  Excuse the playing, it was our first runthrough as a group (and with this song)...


----------



## Willybomb

One of these arrived today too.  Should be interesting as it says it has a preamp attached.  It's probably 3 times the size of the previous board though.









						11.99US $ 5% OFF|150w Mono Channel Digital Power Audio Amplifier With Preamplifier Ne5532 Class D Dc12-24v Subwoofer Amplifier - Home Theater Amplifiers - AliExpress
					

Smarter Shopping, Better Living!  Aliexpress.com




					www.aliexpress.com


----------



## JamieJ

Willybomb said:


> One of these arrived today too.  Should be interesting as it says it has a preamp attached.  It's probably 3 times the size of the previous board though.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 11.99US $ 5% OFF|150w Mono Channel Digital Power Audio Amplifier With Preamplifier Ne5532 Class D Dc12-24v Subwoofer Amplifier - Home Theater Amplifiers - AliExpress
> 
> 
> Smarter Shopping, Better Living!  Aliexpress.com
> 
> 
> 
> 
> www.aliexpress.com


Let us know how this goes!


----------



## Willybomb

> Let us know how this goes!



Ok.  So, I picked up a secondhand 19v@4.5a laptop supply and hooked up the new "150w" board and plugged it into a passive wedge (measuring 10ohm, 12inch speaker and horn of some sort) that I have and compared it to the little blue "60w" board.  The results are thus:

Big Red:
- Turning the volume up on the board will amplify an electric guitar enough to be heard, but it's not going to impress anyone or get louder than a conversation.
- Sticking an Effectslayout Paladin (JC120 preamp/DI) pcb in front of it works too, but the volume isn't still impressive.
- Here's the kicker.  Sticking a buffer in front of it after the Paladin gives you an AMP!!!.  All of a sudden, the Paladin volume is barely on, whereas it was well past 12 without the buffer and still not real loud.  You get the same result using a buffered pedal (a Behringer fx600 in this case) after the Paladin.
- The buffer used was Paulinthelabs' Buffered Y-splitter, but I had the same result when that was followed by a klon buffer.  It's a long story, but I was using a DI/Cabsim that I built a couple of years ago.  The chain inside is Y-splitter one goes directly out, the other goes to: - klon buffer - Sonic Stomp - Lart's Simple Cabsim.  I'll include a pic of that.

The results were a little different with the Little Blue One:
- The little blue one has next to no volume without the buffer.  However, I couldn't get it to work with the DI/Cabsim after the Paladin - it just would not work.  BUT, it did work with the FX600 in front of it (both with the effect on or bypassed) after the Paladin.
- Little blue does NOT like having the input cable inserted into the jack when it's turned on (I suspect it's the same with the output too).  This will cause it to shut down and you will have to cycle the power to get it working again.  However, if the input was fed from the FX-600's output and kept there, you can plug/unplug the fx600's input all day long multiple times without issue.

I noticed more noise with the 150w, but I have noisy power downstairs and it's always been an issue.  I haven't opened them up as loud as they can go, but based on the size and experience on Sunday with the LBO, it's a winner.  Stick it in a 125b (or smaller!) on the pedalboard and you're good to go.  I have another 2 of them on the way.

Edit:  I went back and tried the TPA3116, supposedly 100w mono, and it worked fine with the buffer in front.  It's smaller than the 150w, probably a little noiser.  Didn't run it flat out, just enough to compare with/without the buffer.  Again, the size is about the same width as a 125b, and would probably fit ok, but I'm not seeing any benefit over the smaller 3118.


----------



## Willybomb

Ok, here's my 3116 based build. The vero at the bottom is a dual buffer with the volume pot wired between them, with a 9v regulator and 330n flown off it.


----------



## PBWilson1970

I keep coming back to this circuit and can't wait to see it come to life as a kit or documentation to diy.

In my wish list, I'm hoping for something really simple to go out of one of my preamps (Alembic F1X clone, Intersound IVP, Acoustic 360+ or maybe one of the handful of pedal in a box projects I've made) and into a speaker cab. Not having to bring a full sized amp head will make this so nice for jam sessions at a friend's place without needing a roadie!

Any news about progress on this one?


----------



## Willybomb

PBWilson1970 said:


> I keep coming back to this circuit and can't wait to see it come to life as a kit or documentation to diy.
> 
> In my wish list, I'm hoping for something really simple to go out of one of my preamps (Alembic F1X clone, Intersound IVP, Acoustic 360+ or maybe one of the handful of pedal in a box projects I've made) and into a speaker cab. Not having to bring a full sized amp head will make this so nice for jam sessions at a friend's place without needing a roadie!
> 
> Any news about progress on this one?


Dude, there's really nothing to these.  Build a buffer on vero, run that to a pot, run that to another buffer vero, run that to the poweramp pcb.  I don't even know if you need the 2nd buffer, but I put it there to get rid of any issues having a pot immediately before the pcb.


----------



## PBWilson1970

Willybomb said:


> Dude, there's really nothing to these.  Build a buffer on vero, run that to a pot, run that to another vero, run that to the poweramp pcb.  I don't even know if you need the 2nd buffer, but I put it there to get rid of any issues having a pot immediately before the pcb.


That's great to hear. I've got a variety of buffer schems and layouts (leaning toward the JHS Little Black Box/Buffer?) and this could be a pretty useful item. Thanks for the words of encouragement.


----------



## megatrav

Willybomb said:


> Dude, there's really nothing to these.  Build a buffer on vero, run that to a pot, run that to another vero, run that to the poweramp pcb.  I don't even know if you need the 2nd buffer, but I put it there to get rid of any issues having a pot immediately before the pcb.


Hey thanks for explaining it. Do you happen to have a diagram of how this would be wired up?

Also, I have never used vero. Do you know of any pcb buffers that would work in the same way?

I currently have 2 of these TPA3118 boards and would love to work on wiring them up and running them into a cab


----------



## MattG

I haven't used the tpa311x for guitar duty, but the stereo power amp in my living is my own tpa3118-based DIY job.  It uses two mono tpa3118 PCBs that I made (my first-ever PCB design).  They are not fancy, basically just a copy of the reference implementation in the datasheet (PDF link).  The tpa311x amps were arguably the "darling" of the diyAudio Class-D forum for quite a while.  When TI released the tpa311x series of class-D amps, the were not quite state-of-the-art, but _very_ good, particularly given their price, the availability of cheap PCBs, and simple implementation.  In terms of measured performance (for HiFi use), they are now outclassed by TI's own next-generation chips (e.g. tpa325x), as well as chips from other manufacturers (e.g. Infineon ma12070).

I haven't worked with this chip in a while, but some random thoughts off the top of my head:
 The tpa311*6* and tpa311*8* are exactly the same circuit.  The only difference is the physical package: the -8 is "power pad down", intended for lower-power applications where the PCB itself is intended to be the heatsink; the -6 has exposed metal on the package top, and is intended for use with a heatsink.  (And in my experience, they simply don't get hot.  Before I deployed my -8 amps, I used a -6 mono amps with tiny, glued-on heatsinks in my living room for years, driving 4-ohm speakers... they didn't even get warm.  I think you have to push a sine wave through at max voltage to get the chip to heat up.)
 I don't remember the values off the top of my head, but the amps are designed to be driven by some kind of a preamp (think in terms of hifi applications, e.g. a DAC, actual preamp, even cellphone headphone jack).  The chips are designed for differential input.  I don't know if the PCB discussed here has exposes the negative input pin (for differential input); but you will get a little extra volume feeding the amp a balanced signal.  (If you're breadboarding a preamp, add a phase inverter too, so you can feed + and - signals to the chip.)
 The gain of the amp is set by a voltage divider at the inputs.  There is a table of gains and the corresponding voltage divider values in the datasheet.  I'm not sure about the PCB discussed here, but a lot of the cheaper Chinese boards ship with the gain set to max.  At least for HiFi use, this is usually unwanted, as it tends to produce a bit of audible hiss (i.e. higher noise floor).  In my own PCB I used the lowest (or maybe second-lowest) gain setting.  If I'm not mistaken, lower gain also increases input impedance, which should make it easier to drive.
 There is a newer "version" of the tpa311x, I can't recall the part number now, tpa3128 maybe?  But it's essentially the same measured performance, same (or very close) power, similar simple implementation, but TI improved the power-saving features.  I mention it only because it might be relevant if you want to run off battery.
 The gist of class-D amplification is that the output transistors switch off and on very quickly (typically in the 100's of kHz).  This adds noise to the output signal; it is well above the threshold of human hearing, and implicitly filtered by most (probably all?) speakers.  That said, usually you will find an RLC filter at the output of a class D amp.  This is essentially a low-pass filter to remove most of that switching noise.  Such a filter is generally required for commercial products to get various approvals, as without the filter, your speaker cables become EMI/EMF noise generators.  But if your speaker cable is short enough (e.g. in a guitar combo amp), you can save on implementation complexity and cost by omitting the output filter.  And if you do go with the output filter, big, quality inductors are better (this is measurable, someone over at diyAudio made a table of measured THD with different inductors).
 I'm not sure this is measurable, but when I started playing with the cheap pre-made tpa311x boards, one of the first mods I always did was to replace the generally no-name PSU decoupling caps with quality organic polymer ones (e.g. Panasonic OS-CON).  This could well be confirmation bias (because everyone on diyAudio said so!), but the better caps did seem to improve bass.
 If you _really_ want to get fancy, you can look into post-filter feedback (PFFB) implementations for the tpa311x amps.  This will measurably improve the performance of the amp (at the cost of some gain), which is arguably only useful for hifi applications.  However, the other upside is that it somewhat decouples the speaker load from the amp's output filter.

If nothing else, definitely at least skim over the datasheet.  If you've got a lot of time (and I mean _a lot!_) you can skim the tpa311x threads over at diyAudio, there's all kinds of tips and tricks for working with these amps.  I've always thought that if you had a decent preamp, you could make a respectable guitar amp out of the tpa311x.  It's on my list of things I want to do someday.


----------



## Willybomb

> Do you happen to have a diagram of how this would be wired up?


Not really, but it would go like this:

Guitar - buffer - buffer out to volume pot pin 1, pin 3 to ground, pin 2 to second buffer input, second buffer output to TPA3118.

The IC buffers I've been building have worked fine.  I haven't knowingly used a jfet buffer with it.


----------



## Danbieranowski

Just bought each of these to try your project @Willybomb. 





						Amazon.com: Zerone TPA3116D2 Amplifier Board, Single Channel Digital Power Audio Stereo AMP Module 150W for Audio System DIY Speakers, XR-544 : Electronics
					

Amazon.com: Zerone TPA3116D2 Amplifier Board, Single Channel Digital Power Audio Stereo AMP Module 150W for Audio System DIY Speakers, XR-544 : Electronics



					smile.amazon.com
				





			https://smile.amazon.com/gp/product/B0754225CB/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
		


Thanks for sharing your experience with us. I'll have to put together the buffers and such, but that should be easy enough. Would I want to have separate power supplies on this thing (the amp calls for a much higher voltage/wattage than the buffers would)? So like, two 2.1mm jacks, one going to the amp and one going to the buffers?


----------



## Willybomb

Danbieranowski said:


> Just bought each of these to try your project @Willybomb.
> 
> 
> 
> 
> 
> Amazon.com: Zerone TPA3116D2 Amplifier Board, Single Channel Digital Power Audio Stereo AMP Module 150W for Audio System DIY Speakers, XR-544 : Electronics
> 
> 
> Amazon.com: Zerone TPA3116D2 Amplifier Board, Single Channel Digital Power Audio Stereo AMP Module 150W for Audio System DIY Speakers, XR-544 : Electronics
> 
> 
> 
> smile.amazon.com
> 
> 
> 
> 
> 
> 
> https://smile.amazon.com/gp/product/B0754225CB/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
> 
> 
> 
> Thanks for sharing your experience with us. I'll have to put together the buffers and such, but that should be easy enough. Would I want to have separate power supplies on this thing (the amp calls for a much higher voltage/wattage than the buffers would)? So like, two 2.1mm jacks, one going to the amp and one going to the buffers?


I've got that power amp lying around as well.  It's not bad, maybe a bit noisier than the others, certainly a bit larger. 

I got around the 9v problem by including a 9v regulator and associated caps on the buffer board.  On my latest effort, they're mounted directly on the power socket.  I've cut the end off the PS and put a 2.1mm on that.

You won't get the full 150w out of that board, I think you'll need 24v, but the one you're getting will give you plenty of go regardless.






						Watts/Volts/Amps/Ohms Calculator
					

Watts (W) / volts (V) / amps (A) / ohms (Ω) calculator.




					www.rapidtables.com


----------



## Danbieranowski

Willybomb said:


> I've got that power amp lying around as well.  It's not bad, maybe a bit noisier than the others, certainly a bit larger.
> 
> I got around the 9v problem by including a 9v regulator and associated caps on the buffer board.  On my latest effort, they're mounted directly on the power socket.  I've cut the end off the PS and put a 2.1mm on that.
> 
> You won't get the full 150w out of that board, I think you'll need 24v, but the one you're getting will give you plenty of go regardless.
> 
> 
> 
> 
> 
> 
> Watts/Volts/Amps/Ohms Calculator
> 
> 
> Watts (W) / volts (V) / amps (A) / ohms (Ω) calculator.
> 
> 
> 
> 
> www.rapidtables.com


Yeah that makes sense. Really only interested in it as a quick and easy solid state power amp for testing pedals, so it should work well. Thanks for the info!


----------



## Mike McLane

Would the Simple JFET Buffer sold on this site work???


----------



## Willybomb

Mike McLane said:


> Would the Simple JFET Buffer sold on this site work???


Haven't tried one, don't see why not.


----------



## Mike McLane

I assume that you would just feed the 9vdc in parallel to the buffer(s) as well as the TPA3118?  I made a board off of the layout shown in Stevel's entry above.  Would I just insert the buffers as you described a couple of entries back (input-buffer-volume pot-buffer-TPA3118) to that?


----------



## Willybomb

So I measured the Marshall cab in the videos above at 15ohm, and I used 100Lolwhaats!? into it today.  Again, plenty of volume on tap, not noisy in the slightest.



> I assume that you would just feed the 9vdc in parallel to the buffer(s) as well as the TPA3118?



Yeah, I hook the 24v feed up to pin1 of the regulator, and to the TPA3118 straight off that pin.  Pin2 goes to ground, and Pin3 feeds 9v to the buffers.  The regulator has a couple of caps across Pin1-2 and Pin2-3.  I use unpolarised caps there, but you can use whatever.


----------



## Mike McLane

I know squat about voltage regulators.  Are you talking about something like this. . . .





Can you scratch out a layout as to how this integrates with the buffers??  I get the pin hookups you mentioned above, but I'm unclear as to the reference to caps.


----------



## Willybomb

It's a bit rough, does this help?


----------



## Mike McLane

Thx!  Actually I was going to make up the Simple JFET Buffer off of PPCB rather that an IC based circuit (unless somebody has a reason to go with the IC based solution).  I was most curious about a) ID'ing the right voltage regulator and b) the calrifying the caps linking the pins on it.  The cap btw pins 2 & 3 is 100u, but I can't make out the value of the one btw pins 1 & 2.  Pls clarify.


----------



## Willybomb

Mike McLane said:


> Thx!  Actually I was going to make up the Simple JFET Buffer off of PPCB rather that an IC based circuit (unless somebody has a reason to go with the IC based solution).  I was most curious about a) ID'ing the right voltage regulator and b) the calrifying the caps linking the pins on it.  The cap btw pins 2 & 3 is 100u, but I can't make out the value of the one btw pins 1 & 2.  Pls clarify.


On the regulator?  330n between pins 1 + 2.  100n between 2 + 3.

I used an IC buffer as I could use the 2 sections in a TL072.  The current amp I'm building has a TL074 as a 3 way splitter, and a separate buffer.  It splits to the (external) amp, cabsim and XLR driver, plus a send/return for the volume control.  It's not labelled yet, but it works.

I'm using the schematic here for my buffers





						Buffered Y Splitter Stripboard Veroboard
					

Electronics Projects For Hobbyists Makers And Hackers With Stripboard Layouts




					paulinthelab.blogspot.com


----------



## awdevito

Been following this thread for a while so I thought I would post my test results as well! I decided to go full-bore and make a little amp in the box with the PedalPCB Valhalla Distortion (based off the Diezel VH4 preamp pedal).

Took a few days and a lot of planning - I added a switchable FX loop as well and wanted the volume/presence/depth knobs all in different locations. But everything turned out really well! Using a 18v 3.5 amp power supply I got off Amazon. Center positive!

*The result:* Very impressed... it is insanely loud! Amazing we have come this far in technology... A cheap and easy to use module!

There was someone saying they were unsure if this could keep up with a drummer and to them I say... you are either crazy or you have to put a stronger preamp in front. It is _deafening _and I have 100 watt tube amps to compare it to. Without my attenuation I couldn't even get it to 1/5th of the way up. Even with earplugs, I couldn't go past halfway because I was worried my paint would start to peel and the people in the next town over might hear.

I think I will switch the output to be the line out pad instead of dedicated output for going to a power amp (see the Valhalla Distortion schematic to know what Im talking about) because the volume is really just too much. I intend for this to be a practice amp with a 1x12 cab I'm building.

All in all, a really easy way to have a great versatile amp. Can't wait to build more!





Two big switches are power (left) and mute (right). Mute just disconnects the two mute pads from the TPA3118 module.





Top switch is an FX loop that is bypassed when the switch is down or when there is nothing plugged in.





She lives!

*Sound test!!!!* Don't judge the playing too much. First sound is NON-attenuated at 1/6th of the volume or so and then I attenuate the signal with the Two Notes Torpedo Captor X at -20db. Thank goodness, because it is still loud as hell! Sorry the first still in the video is upside down haha.


----------



## Robert

awdevito said:


> Been following this thread for a while so I thought I would post my test results as well!



That looks and sounds awesome.


----------



## awdevito

Robert said:


> That looks and sounds awesome.


From the horse's mouth! Thank you. All my creations are made in honor _of your _hard work!


----------



## Willybomb

Ok, so I get a few stupid pedal ideas occasionally and things like this happen:

- Direct (buffered) pass through to normal amp.
- Larts Simple Cabsim to THCustoms Linedriver XLR
- TPA3118 output.

The volume knob only affects the TPA3118.  The guitar signal is split using the vero layout I posted above.

Guitar output goes to Buffer A input, Output 1 goes to Volume 1, Output 2 goes to the Cabsim, output 3 goes to the passthrough output.
Buffer B Input is used for the volume knob return (pin 2), Buffer B Out goes to the TPA.  Volume pin3 goes to ground.


----------



## Mike McLane

Willy - I built the attached and am wondering where/how to insert the PPCB JFET buffer.  I assume either immediately upstream or downstream of the 220n cap/volume pot.  Pull power directly off of the DC jack into the 7809 assembly then to the buffer?  Any feedback would be appreciated. . . . FROM ANYBODY!?!?!?  Hells bells, if somebody could draw a schematic that incorporates the voltage regulator and buffer into this mess it would be HUGELY appreciated.


----------



## Willybomb

I don't *know* that it matters where the buffer goes as the amp works properly with a buffered pedal in front of it but I would certainly put one between the volume pot and the amp at a minimum. I just put a buffer on either side of the volume pot to make sure the pot doesn't interfere with anything other than the level going into the amp.

This is the schematic I used with the 100lolwhaats and forms the basis of what I did in the post above.

The buffers I use are basically the ones shown here: https://paulinthelab.blogspot.com/2012/04/buffered-y-splitter-veroboard.html or as in the next pic.

You just run the 24v to pin 1 of the 7809, and to the +ve of the 3118.

I've also just had a couple of 24v@5A power supplies arrive, so that should be fun...


----------



## Elijah-Baley

The newx year I want to buy a TPA3118. I looked at that for a long time.
To make it sounds good and reasonably loud I hoped it was enough put in front of it a kind of preamp like Dr. Boogie or Tight Metal, or something less distorted like a Guv'Nor or a Bluesbreaker. And of course a clean preamp like the Tonemender or a simple Fetzer Valve.
I have still understand well the Willybomb's buffer story. 

In this moment I have just a cheap homemade 1x8 cab with a cheap guitar speaker 15w 8 Ohm. But I guess that is too little for the TPA3118.
Could I use the one of both the 12" speakers of my amp with a flying connection?


----------



## Willybomb

Elijah-Baley said:


> The newx year I want to buy a TPA3118. I looked at that for a long time.
> To make it sounds good and reasonably loud I hoped it was enough put in front of it a kind of preamp like Dr. Boogie or Tight Metal, or something less distorted like a Guv'Nor or a Bluesbreaker. And of course a clean preamp like the Tonemender or a simple Fetzer Valve.
> I have still understand well the Willybomb's buffer story.
> 
> In this moment I have just a cheap homemade 1x8 cab with a cheap guitar speaker 15w 8 Ohm. But I guess that is too little for the TPA3118.
> Could I use the one of both the 12" speakers of my amp with a flying connection?



It'll push the 15w@8ohm without issue and you can fly a speaker to it, just don't run it into the amp itself. The 4x12 cab in the video I'm playing the TPA3118 into measured 15ohms, and the wedge I test on at home is 10ohm (12inch woofer + tweeter).  I haven't opened it up fully but it keeps up with bass, acoustic drums, and vocals without issue.


----------



## PBWilson1970

The layout posted above looks very do-able and I've got a few extra enclosures laying around...

I'm planning on building a JHS Little Black Buffer clone or possibly a dual one to put near the front and also at the end of my signal chain so I guess I'll be covered. 

As people build these, I'd love to know what preamps you'll be using. Within the next few weeks I oughta have a handful finished and ready to try out. So far I've got an Alembic F-1X, Intersound IVP, Acoustic 360+ and a few other amp-in-a-box circuits in the works.


----------



## Elijah-Baley

Willybomb said:


> It'll push the 15w@8ohm without issue and you can fly a speaker to it, just don't run it into the amp itself. The 4x12 cab in the video I'm playing the TPA3118 into measured 15ohms, and the wedge I test on at home is 10ohm (12inch woofer + tweeter).  I haven't opened it up fully but it keeps up with bass, acoustic drums, and vocals without issue.



But, if I supply the TPA3118 at 18v (and that could be even something more) it should be over 15w output power, isn't it? I thought it was a problem for the 15w speaker.
I want to be very careful with it, because the speaker it's very low cost and the cabinet it's just a wood box I found. If I ruin the speaker I can't and I don't want to replace it with another expensive speaker and put it into a box of wood that is not a real cabinet.
I use this cabinet just to play with some mini 9v amp like LM386 or similar.

Once I clarified this, I'm still worry about the PSU I can use with this amp. I don't have any laptop power supply, I have to buy it, probably I can find it only new. I'm thinking to buy it from ebay or amazon in EU.
Do you can advice some tested models that will work fine? I afraid to buy and find it noisy and useless.


----------



## Willybomb

Elijah-Baley said:


> But, if I supply the TPA3118 at 18v (and that could be even something more) it should be over 15w output power, isn't it? I thought it was a problem for the 15w speaker.
> I want to be very careful with it, because the speaker it's very low cost and the cabinet it's just a wood box I found. If I ruin the speaker I can't and I don't want to replace it with another expensive speaker and put it into a box of wood that is not a real cabinet.
> I use this cabinet just to play with some mini 9v amp like LM386 or similar.
> 
> Once I clarified this, I'm still worry about the PSU I can use with this amp. I don't have any laptop power supply, I have to buy it, probably I can find it only new. I'm thinking to buy it from ebay or amazon in EU.
> Do you can advice some tested models that will work fine? I afraid to buy and find it noisy and useless.


My understanding is that you want your amp to have more headroom that the speaker so the speaker doesn't get a squarewave sent to it.  You'll be able to try it out carefully as I was initially testing these on some little stereospeakers.

As far as powersupplies are concerned, I've picked a few up from the local "tip shop", mostly 19v@3.5a, cutting the jack off and replacing with a 2.1mm wired for center negative.  They work fine.  I have picked up two of these 24v@5A just the other day so I can get the max out of the boards I have.  I've been in covid isolation this week so I haven't put the new jacks on them to try them out.









						DC 24V 2.5A 3A 5A 6A Transformer Power Supply Adapter For LED Strips 5.5x2.1mm  | eBay
					

Find many great new & used options and get the best deals for DC 24V 2.5A 3A 5A 6A Transformer Power Supply Adapter For LED Strips 5.5x2.1mm at the best online prices at eBay!



					www.ebay.com.au
				






PBWilson1970 said:


> The layout posted above looks very do-able and I've got a few extra enclosures laying around...
> 
> I'm planning on building a JHS Little Black Buffer clone or possibly a dual one to put near the front and also at the end of my signal chain so I guess I'll be covered.
> 
> As people build these, I'd love to know what preamps you'll be using. Within the next few weeks I oughta have a handful finished and ready to try out. So far I've got an Alembic F-1X, Intersound IVP, Acoustic 360+ and a few other amp-in-a-box circuits in the works.


I've got a couple of Effectslayouts' JC-120 preamp clones that I'm going to pair up with a Freedman Supreme from Pcbmania in a DD, switching between the two.  I've also got a couple of M800 pcbs in the cart here to try out, again swapping between the two.

I'm currently running a Mooer Preamp Live into these amps.


----------



## Elijah-Baley

Thanks for your reply.

I have two question: one about the *speaker*, seen the higher wattage I could get with this amp than my 1w - 2w amps I built until now; and another one about a good and right *PSU* to use with it, being laptop PSU are not made for audio application, though volts and amperes are often more than good.

Maybe it's something I still don't know, but I thought that if I use a *60w* amp with a *15w* speaker, the speaker can't resist to the power of the amp and I will damage it. Am I wrong? I have a pair of tv speaker 8 Ohm 30w, and my amp is a 120w with two 12" speaker 8 Ohm (individually), I can't read anything about the wattage, but the amp is 120w, and those works in parallel and are ok, of course.

About the headroom, I think it depends from the voltage of the PSU. The laptop type PSU are the better thing we could use with this amp, I assume. At least 2.5A, better 3A or over. And 18v at least, but often it has around 19v, that is good enough. I guess with a 24v I'll get even more headroom, I mean more watt, so more volume and less distortion. If I have to replace the plug and/or invert the polarity I can do it, I'd buy the PSU for that, so no problem with it, I guess.

About the preamp I'm not too much worried about it. I want to make some experiment and I think I'll build this amp stand alone to try it with the pedals I can use as preamp, in this way I can supply the parts individually without power/voltage issue.
Later, who knows, I could build a dual channel preamps + amp, all in one. It's a thing I tried to do in the past with a about 5w amp DIY, but I'm stuck because the PSU.


----------



## Willybomb

Well, I've hit a roadbump.  My 9v regulator is getting blown when I swap in the 24v PS.  Not sure what's going on there.  Not an issue on a straight amp build as the buffer circuit can take 24v, but I'm not sure the other circuits in my 60watt build can (the cabsim and xlr driver).  Certainly, when I hooked everything up to the straight 24v it started smelling a bit bad...


----------



## Elijah-Baley

Is the 7809 was hot? Maybe it need an heatsink at higher voltage?
Not sure, but... what about the current consumption? At 24v you need too much ampere for the 7809?


----------



## zgrav

Elijah-Baley said:


> Thanks for your reply.
> 
> I have two question: one about the *speaker*, seen the higher wattage I could get with this amp than my 1w - 2w amps I built until now; and another one about a good and right *PSU* to use with it, being laptop PSU are not made for audio application, though volts and amperes are often more than good.
> 
> Maybe it's something I still don't know, but I thought that if I use a *60w* amp with a *15w* speaker, the speaker can't resist to the power of the amp and I will damage it. Am I wrong? I have a pair of tv speaker 8 Ohm 30w, and my amp is a 120w with two 12" speaker 8 Ohm (individually), I can't read anything about the wattage, but the amp is 120w, and those works in parallel and are ok, of course.
> 
> About the headroom, I think it depends from the voltage of the PSU. The laptop type PSU are the better thing we could use with this amp, I assume. At least 2.5A, better 3A or over. And 18v at least, but often it has around 19v, that is good enough. I guess with a 24v I'll get even more headroom, I mean more watt, so more volume and less distortion. If I have to replace the plug and/or invert the polarity I can do it, I'd buy the PSU for that, so no problem with it, I guess.
> 
> About the preamp I'm not too much worried about it. I want to make some experiment and I think I'll build this amp stand alone to try it with the pedals I can use as preamp, in this way I can supply the parts individually without power/voltage issue.
> Later, who knows, I could build a dual channel preamps + amp, all in one. It's a thing I tried to do in the past with a about 5w amp DIY, but I'm stuck because the PSU.


The amp works fine with a lower voltage power supply -- even 9 volts.  It just puts out less power, which may not be a problem if you are planning to use it with a speaker rated at 15 watts.   12 volt power supplies that run at up to 2 amps would be worth considering.  cheaper, less strain on the amp, and less likely to damage your speaker.


----------



## zgrav

Willybomb said:


> Well, I've hit a roadbump.  My 9v regulator is getting blown when I swap in the 24v PS.  Not sure what's going on there.  Not an issue on a straight amp build as the buffer circuit can take 24v, but I'm not sure the other circuits in my 60watt build can (the cabsim and xlr driver).  Certainly, when I hooked everything up to the straight 24v it started smelling a bit bad...


A heat sink is required when you are pushing the regulator near its maximum limit.   The datasheet suggests it can take 35V but the electrical characteristics list 25V as the max.  A 24V I would recommend a heat sink and thermal paste between the regulator and heat sink.  Maybe consider running the voltage to the regulator through a couple of diodes first to lower the voltage.


----------



## Willybomb

zgrav said:


> A heat sink is required when you are pushing the regulator near its maximum limit.   The datasheet suggests it can take 35V but the electrical characteristics list 25V as the max.  A 24V I would recommend a heat sink and thermal paste between the regulator and heat sink.  Maybe consider running the voltage to the regulator through a couple of diodes first to lower the voltage.


Good points.  I'll try that.


----------



## Elijah-Baley

zgrav said:


> The amp works fine with a lower voltage power supply -- even 9 volts.  It just puts out less power, which may not be a problem if you are planning to use it with a speaker rated at 15 watts.   12 volt power supplies that run at up to 2 amps would be worth considering.  cheaper, less strain on the amp, and less likely to damage your speaker.


My only 9v PSU is an old Boss red label, but it's only 300mA. Is the TPA3118 max current draw 50mA? I'm not sure.
To get 12v I should use extra circuits or I have to buy a 12v PSU, but in this case I prefer to buy a 19v laptop PSU. I prefer higher wattage to benefit better the amp.

*My speakers*:
Cheap Speaker 8" - *8 Ohm* - *15w* into a wood box.
Marshall Speaker 8" - *4 Ohm* - *30w* in a small guitar amp.
Crate Speaker 12" - *8 Ohm* - *?w* (the amp is 120w solid state, so I think it's over 50-60w).
or
two Crate Speaker 12" - 8 Ohm - ?w in parallel 4 Ohm.

*With 8 Ohm speaker* I can get:
At 9v about 5w.
At 12 about 8w.
At 19v over 20w. (Not for Cheap Speaker).

*With 4 Ohm speaker* I can get:
At 9v about 8w.
At 12 over 15w.
At 19v over 35w. (Not for Marshall Speaker).

Conclusion, the 19v PSU it will be ok just with the Crate Speaker.


----------



## Willybomb

Heads up - the little blue 60w ones will die with 24v.  One bloke found out on the DIYstompboxes(unofficial) FB group, and I had it happen to me when I tried 24v rather than 19v.  The caps are rated to 25v, but clearly not really...


----------



## zgrav

you will be OK with the 19v supply on any of those speakers as long as you do not try to play the lower watt ones too loud.


----------



## Elijah-Baley

Ok, so it's enough keep the volume under 3/4 if I'll use a 19v PSU.

Maybe I could try to build a 12v regulator circuit, just to to build it and see how the TPA3118 will sound with the smaller speakers.

I have to wait to make some money to order the amp and the PSU.


----------



## Mike McLane

I finished inserting the Simple JFET buffer btw the input and VOLUME knob and it seems to work EXCEPT the output has shift decidedly to be more "trebley" . . . less bottom end, sharper highs. . . giving it a somewhat thin sound.  The shift isn't huge, but definitely less satisfying than without the buffer.  I'm using an HX Stomp set for _line level_ output so in theory the buffer should be unnecessary, but other front ends may require it so I thought I'd experiment and it's presence shouldn't hamper the HX signal other than its obviously is "EQing" the signal. Anybody have any thoughts?


----------



## Robert

What cap values did you use for the JFET buffer?


----------



## Mike McLane

I used the values prescribed on the Simple JFET Buffer build docs.  I powered with a 19vdc computer PSU and ran the buffer power thru the 9vdc voltage regulator and cap values WillyBomb suggested above.  The layout is attached.


----------



## Willybomb

Mike McLane said:


> I used the values prescribed on the Simple JFET Buffer build docs.  I powered with a 19vdc computer PSU and ran the buffer power thru the 9vdc voltage regulator and cap values WillyBomb suggested above.  The layout is attached.


I'm not using that 220n on the volume pot.  Ditch it, and stick another buffer after the pot.


----------



## Willybomb

Ok, further updates:

I boxed up the big red 150w PCB in the usual manner - input, buffer, volume pot, buffer, amp - and found it way too noisy.  The 24v supplies I've gotten have a high pitch, low volume noise in there with any of my amps so I'm using the 19.5v ATM, but it was pretty unusable even with that.  I've replaced it with the 100w medium blue pcb.  That deals with 24v fine, but the PS noise isn't acceptable.  The little 60w boards seem to be the best compromise.

You might remember 100Lolwhaats? from earlier in this thread.  I sent that to a friend in Melbourne to try out with his band.

He finally tried it out, and this is our convo:

- Did lolwhaats hold up?
- Did it ever! Sounded great!
- Sweet.  What did you run it into?  Keep up with the drums et al ok?
- Had the 1×12. I put it up on a bench to give us more floor room and it was plenty loud enough. Had it dimed with helix volume set at about 11 o'clock. Sounded awesome with the all the clean and dirty stuff. The only problem was the acoustic guitar didn't sound great. Must need a full range speaker...
- Well, that's handy to know.  If the acoustic was going through the helix that would be a problem maybe.  I don't think these things work that well with a guitar going straight in, at least that's my experience.
- Wasn't an actual acoustic. Just the variax into a patch with a Comp to boost the volume and a graphic eq. And some reverb.

So that might be something to look into down the track.


----------



## Paul.Ruby

Schematic and PCB layout removed from this post in favor of new ones below...

I just built a few pedal-board amps in a 1590B case. Here's my preamp design, which runs off the same 24V power supply. Spent a lot of time futzing with C5 and C6 to get the top end just right without needing any extra tone controls. This shows a bright switch but I have it hard-wired on in this build.  R1 sets the input gain and I dialed this in to work well with pedal levels. Goal was to be as simple as possible. Just a volume knob and maybe a bright switch.
I have a PCB layout for it as well... Attached zip is for expressPCB. Pic of guts below. The black coating is for insulation, not to hide anything... There's just a volume pot and I have the "bright switch" jumpered on.  The volume pot is where a footswitch would usually be. You can just see the edge of it on the right side of this pic behind the preamp board. R5 is mounted on the input jack. R13 is mounted on the LED. C8 does not exist in my PCB layout but included in the schematic in case someone can lay it out better then I did.


----------



## Paul.Ruby

Paul.Ruby said:


> I just built a few pedal-board amps in a 1590B case. Here's my preamp design, which runs off the same 24V power supply. Spent a lot of time futzing with C5 and C6 to get the top end just right without needing any extra tone controls. This shows a bright switch but I have it hard-wired on in this build.  R1 sets the input gain and I dialed this in to work well with pedal levels. Goal was to be as simple as possible. Just a volume knob and maybe a bright switch.
> I have a PCB layout for it as well... Attached zip is for expressPCB. Pic of guts below. The black coating is for insulation, not to hide anything... There's just a volume pot and I have the "bright switch" jumpered on.  The volume pot is where a footswitch would usually be. You can just see the edge of it on the right side of this pic behind the preamp board. R5 is mounted on the input jack. R13 is mounted on the LED. C8 does not exist in my PCB layout but included in the schematic in case someone can lay it out better then I did.
> 
> View attachment 22915


Tops side pic as well...


----------



## Elijah-Baley

Why the output jack is made of plastic? It's have to do something with the ground?


----------



## Willybomb

Elijah-Baley said:


> Why the output jack is made of plastic? It's have to do something with the ground?


Yeah, you can't ground the output to the enclosure.   First google hit:

"That's because most amps and receivers these days *have bridged (or differential) output*. Both the negative terminal and positive terminal of bridged output amplifiers send a voltage signal to the speakers, so there is no common ground."


----------



## Paul.Ruby

Elijah-Baley said:


> Why the output jack is made of plastic? It's have to do something with the ground?


Exactly. The speaker output lines must not be grounded. The negative of the input, however, is common with the negative of the power. So, I have the negative of the input to the preamp and the negative of the power supply directly connected to the case.


----------



## Paul.Ruby

Since I can't leave well enough alone, I made a version of the PCB without the mounting holes since I don't use them. Both versions are in the attached zip file for expressPCB. I'm adding a 3A diode (1N5408) in series with the input supply line to drop the voltage from 24 down to ~22.5 since I see some reports here of the caps blowing on these little power amp boards. Updated schematic:



Construction photos... Super glued the LED to get it down tight to the case and well insulated. R13 is soldered directly to the LED and leads are heat shrunk wrapped.



Modular connections using JST-VH for power and speaker connectors and KF2510 for all the signal lines. Note this PCB is a bit earlier than the one in the attached zip file. The input and power connectors are too close together on this one. All resistors are 1/8W to squeeze this all down tight. The 10uf electrolytic is one of the short-fat types because the tall ones will touch the volume pot. Of course, all polyester film caps in the signal path with the exception of the two bright caps, C5 and C6 are ceramic. (This board has a film cap for C5.)



Showing the speaker line run and how the amp board will flip upside down over the power jack. Power jack location is important as the lead end up between the JST-VH connectors and the 330uF caps. Tape is wrapped around the jack to avoid any contact with things on the amp board.



All of the connectors in place...



1N5408 added to drop input voltage a little and ensure correct polarity at the input.



Heat shrink the 1N5408.



Wire nut all the power lines together. Can solder and heat shrink, but this lets me take things apart until I'm sure it's final.



Snug fit. Fully insulated the board and the case with liquid tape.


----------



## Paul.Ruby

As others have pointed out, must use a good power supply. I use the 24V auxiliary output on a Cioks DC7 and it's dead quiet. Best pedal board power supply ever made. I just got a cheapo 19V from amazon and it whines. Now I need to see if there is a remedy for that...

After some testing, the problem is direct power supply noise. The TPA3118 module itself is rejecting this noise. Very quiet until I attach the preamp. Found no evidence of ground loop or RFI getting into the preamp. Purely power supply noise. Solution is simple. The preamp draws very little current, so adding a 470-ohm resistor in series with the supply line to the preamp solves the problem. The RC filter of 470 ohm and the on-board 10uf resolves the noise completely.

Post above has been updated with corrected schematic and PCB.

Still have a problem. It's quiet with the cheapo power supply and a guitar plugged in directly and sounds nice on it's own. Fendery clean with the choice of EQ in the preamp. But, married with my pedal board at large, some of the whine comes back if I use the cheapo power supply. Still dead quiet using the Cioks DC7, of course. My guess is differential ground noise between the board and the amp with the cheapo supply. Next step is to see if I can get a solid, clean ground across all the pedals with a cheapo power supply in the mix.

And again... Further testing. My choice of cheapo supply has a 3-prong, grounded power cord. The earth ground of the mains line is directly connected to the negative of it's 19V output. This allows the cheapo supply to directly insert it's ground noise into a ground loop when connected to the pedal board. The solution to this problem is to ensure one, and only one, connection of your pedal supplies back to mains earth ground. My pedal board is already earth grounded via the Cioks DC7. The added grounding via the cheapo supply causes the noise. Removing the earth ground on the cheapo supply mains line eliminates the noise. Finally clean and works really well. 

Summary of my learning building these things...

TPA3118 is great. Flat frequency response (which is too dark on it's own, IMO). And rejects the noise of a cheapo power supply very well.
Need a preamp to boost guitar/pedal/instrument level up to line level to drive the TPA3118 well.
Fender-like EQ choice for the preamp works really well. Flat response from 20hz up to ~1kHz and then passive high-pass to boost the top end above ~1khz. (See C5/R6 and C6 in the schematic. Tweak to taste.) 
Cheapo power supply can work. TPA3118 can handle it but the preamp cannot. Need a good RC filter or better regulator to get clean power to a preamp. With ~20V available, an RC filter is fine for a simple preamp like this drawing under a mA. 
Don't allow more than one path from circuit ground back to mains earth from your pedal board supplies, especially if using a cheapo supply for the TPA3118. Do make sure you have ONE solid earth ground from your pedal board for safety, of course. 
Cioks DC7 is awesome and can drive the TPA3118 using it's auxiliary 24V output. (I was already doing this with a quilter amp, which is also really nice). 
Next up... I've ordered three different EQ boards from here to make some bigger, more full featured pedal board amps. I have a "Cold Turkey", "Box and All" and a "6 band EQ (Pot version)" boards that all arrived today. Nice timing.  And I have a couple 100W TPA3116 boards to try out.


----------



## Paul.Ruby

Just finished using a Cold Turkey EQ as the preamp. Have not put it in a case. Much more gain is needed to bring instrument level up to line level. Here's the schematic, which is just component changes on the PCB, all shown in red. Power supply is 24V, so choose capacitors to suite the higher voltage. 


Summary:

Not using the foot switch, LED or R100 on the board. LED will all be off board, but you could change R100 to 47k and use the LED circuit on-board.
Main change is the input gain: R4=330k; R5=47k. This gets the signal up to line level.
Using TL072 but JRC4558 would work, too.
D100 is replaced with 220R to act as an RC filter for the power supply. I will have a 1N5408 off board for polarity protection and to drop voltage a little, just like the previous simpler board. This RC filtering is very important for use with cheapo 24V power supplies.
Replace C7 with a wire. I don't see the point of C7 but not important.
Leave out R14.
Change R15 to 10k.
Change volume pot to A100K.
Changed R1 and R3 to 1M. Not important but noise in a resistor is proportional to value, so I don't go higher than 1M for these bias things.
Left out C1. Not important.
I used film caps for the 1uf. With the removal of C7, there are no electrolytic in the signal path. All polyester.
Very easy build since the PCB itself needs no modification. Was actually much easier than making my own PCB for the simple volume preamp previously. The amp will fit where the footswitch would have been. Time case it up. Should easily fit in a 125B. Maybe a 1590B. Action Shot:



That's the 100W TPA3116. That will not fit in a 125B...


----------



## Paul.Ruby

The "Box and All EQ" also works really well with the TPA3118. Cold Turkey seems to boost midrange, which is cool and a bit more '80s marshall EQ vibe. Box is more fendery. Both work really well. Here's the altered schematic, again just making component changes to pair with the TPA3118.



Summary:

Level POT changed to A100k. Did not need nearly as much gain boost to get to line level as the Cold Turkey did.
Use 25V or higher for C100.
Leave out the LED and R103. But, can include if you like and change R103 to 47k.
Change D100 to 220R for RC filtering of cheapo power supply. Lose about 2V, which doesn't matter at 24V.
Changed Vref resistors R100/101 to 100k to reduce current draw.
Jumpered C7 and C8 and left out R11. The DC bias voltage output from the op-amps is already at Vref.
This may allow a small DC current through the level pot due to non-zero offset voltage at the input of IC2.2.
So, you may choose to leave in C7 to be sure there is zero DC current in the level pot.
And 1uf film cap is fine for C7.

Changed C1 to 100nf. 1u is overkill.
Changed C2 and C9 to 1uf film caps because I prefer to leave electrolytic out of the signal path.


----------



## Paul.Ruby

And finally, the changes to the 6-band EQ to pair with TPA3118. This needs a volume pot added. Primary gain increase is from R7 but also a bit from R3 and R9.  Since the on-board LED come after D100 on this one, do not use the on-board LED since it is on the wrong side of the 220R resistor used to filter the cheapo power supply. This one is my least favorite of the bunch. Need to spend time tweaking the knobs to dial it in but it certainly has a crazy amount of EQ control. I like the original with just a volume control. Took me a bit to tweak the hard-wired EQ, but now it is plug'n'play. For more control, I like the cold turkey version as a #2. Box and All is also good but more stuff and bigger comes in just behind cold turkey.


----------



## Paul.Ruby

125B cases with Box And All on the left and Cold Turkey on the right.


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## Paul.Ruby

By the way, as others have pointed out, these things make a big pop when powered on and off. A proper design would have a power on delay and detection of power off for instant disconnection. I can confirm that having the mute pins shorted eliminates all sound, including power-up/down pops. Power on delay can be short, maybe 100ms. Power cut detection must be fast.


----------



## Paul.Ruby

EDIT #2: I've decided this is not worth the effort. The only way to really avoid pop is with proper behavior. Don't plug in a speaker cab until everything is powered. Unplug speaker cab first for power down. A mute button or stand-by on the amp might be a nice-to-have, but still requires proper behavior. 

EDIT: Made some tweaks. R7 changed to 56k to mute if power supply is below about 17V. Trying to be aggressive with this to err on the side of muting if voltage is not adequate. Increased R4 to 1M and C1 to 100uf to get a longer power on delay. Made these changes because the pedal board has a lot of stuff that is all acting badly during power up and down. I can hear two pedals ticking relays during power on and they are making cracks and pops on power down. So, this is an attempt to get the power amp muted for as much of this as possible. *But, it's still not good enough* once combined with other things that can behave badly. Maybe a stand-by switch on the amp is the best option. I've added one to the schematic. When open, the amp is muted. I'm still stewing on this. I find myself wanting a circuit that will be stuck on mute at power on until a "go" button is pushed. Just keep the amp on mute for all power-on until user input is made. This would be a flip-flop with a toggle switch and designed to always power up in the muted state.

Here's a mute circuit I have on a breadboard and works really well. I'll probably wire this by hand and add to the pedals I've already built rather than do a PCB. The brown box is what is already on the TPA3118.

The mute pins on the TPA3118 are connected together, making mute the default behavior instead of unmute. Then, Q1 and Q2 are an AND gate to unmute. Both transistors must be on to unmute.  Q1 has a delayed turn-on, held off by C1 when power is first applied. Will take ~100ms with 10uf. Q2 is meant to turn off very fast at power loss. R8 will pulldown the base of Q2 very fast when 24V is lost.

My only remaining concern is that C1 must be discharged to be prepared for the next power on. So far, this doesn't seem to be a problem. Manually pulling power and reapplying fast is not causing any pops. I don't think any further complexity is needed.


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## Willybomb

How are you getting around these boards blowing at 24v?

I'm also getting a lot of hum with mine when it's paired with a particular pedal that has a switchable 9->18v chargepump.  The pedal is powered from a 1spot, and the amp is powered by a laptop supply @19v.  It's starts off relatively quiet and then builds up.  I think I gave the good supply to a mate to use with the 100lolwhaats!? build.

The big problem here is that when we start adding anti-this/that stuff, we start getting away from the small form factor possible with these, and then we might as well start playing with transformers and mains power.


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## Paul.Ruby

I added an 1N5408 in series with the supply to drop about 1.5V. And double checked that the supply I'm using is not behaving too badly. Really need to make sure you have a power supply that does not overshoot on power up.  From one of my earlier posts, here's the stuff I had to do about noise and hum. Supply filtering to sensitive circuits and ground loop avoidance are key.


> Summary of my learning building these things...
> 
> TPA3118 is great. Flat frequency response (which is too dark on it's own, IMO). And rejects the noise of a cheapo power supply very well.
> Need a preamp to boost guitar/pedal/instrument level up to line level to drive the TPA3118 well.
> Fender-like EQ choice for the preamp works really well. Flat response from 20hz up to ~1kHz and then passive high-pass to boost the top end above ~1khz. (See C5/R6 and C6 in the schematic. Tweak to taste.)
> Cheapo power supply can work. TPA3118 can handle it but the preamp cannot. Need a good RC filter or better regulator to get clean power to a preamp. With ~20V available, an RC filter is fine for a simple preamp like this drawing under a mA.
> Don't allow more than one path from circuit ground back to mains earth from your pedal board supplies, especially if using a cheapo supply for the TPA3118. Do make sure you have ONE solid earth ground from your pedal board for safety, of course.
> Cioks DC7 is awesome and can drive the TPA3118 using it's auxiliary 24V output. (I was already doing this with a quilter amp, which is also really nice).



Very hard to debug hum and noise issues via chat. The one-spot is connecting all the pedal grounds together via the daisy-chain and also have a ground path through all the pedals via the instrument cables. That's a ground loop and one offending pedal anywhere in that chain could inject noise. Seems you know you have an offending pedal. Try running just that one pedal from a completely independent 9V power supply or a battery to see if removing it from the overall ground loop solves the issue.

You also need exactly one earth ground from your board's circuit ground for safety and need to be careful about sneak paths for ground, such as a direct line from the board to your PA or recording equipment. I use a radial stage bug for direct send with ground lift. The one spot isn't grounded. No idea if your chosen 19V supply has an earth ground. Since your 1-spot is not earth grounded, might make sense to use a supply for your pedal amp that is earth grounded. My Cioks DC7 provides my single safety earth ground to my pedal board.

My power supply has a smooth ramp and settles at 24.4V. Then it's dropped to ~23V internally through the 1N5408. This is the cheapo supply I'm using to make sure things work, not the Cioks DC7. This cheapo supply has no earth ground.


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## Paul.Ruby

Simplified mute. This only has power-on delay, which can be tuned to what ever delay via C1. The fast mute during power-down was useless because it only helps when the 24V power plug is pulled directly out of the amp, which should be never. Power-on delay is debatable as the only value add. Still no substitute for proper behavior. I might layout a new volume-only-preamp with this since it's so simple.



Retrofit modules are built. Used 220uf for C1 to get ~5 seconds of power on delay. Built them as free-flying components and heat shrunk each junction and then the whole thing. Here's an installed module (the red heat shrink blob).


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## Paul.Ruby

Knowing that some folks have had the amps blow up makes me wonder if over-voltage protection should be included in a general design... Or at least include the pads for such things if folks want...


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## Paul.Ruby

In case anyone is interested in the volume-only preamp, here's my latest (final?) PCB. All 3 revisions are in the ExpressPCB file. Rev 3 adds the power-on delay and the LED resistor to the board. Does not add over-voltage protection. That's a high-power thing that should be elsewhere if desired. Also lined up most of the header pins in a row to use whatever headers are available. I quickly used up all my two's with prior layouts. And reduced the power connection to KF2510 since this draws about 1mA, even with the LED.

Schematic to go with this is below as well... Anywhere a 100nf is suggested, 47n or larger will work. Every one of them is intended to pass full bandwidth. I had an abundance of 82n, so used them for these two boards... I still used a 1uf for C4 in these but even 47n is plenty for that, too.

The 220uf, C12, in the power-on delay can be chosen for what ever delay you like. 220uf is ~5seconds to stay off while all the other stuff on the pedal board settles in. This cap will only ever hold 1V, so can be the lowest voltage you can find to keep it small. The 10uf, C11, should be 35V. Can be larger than 10uf if you like, too. I had some 47uf, 50V so used those here.

The NPN transistor type is not important. Any silicon BJT is fine. I have a small pile of counterfeit J201 from ebay that happen to be decent NPN BJTs instead. That was a fun discovery... *EDIT: The same transistor can also feed the cathode of a stand-by LED if desired. Can be a 2nd LED or wire the cathode of the single LED to the stand-by connection instead of direct to ground if you prefer the LED to mean "Engaged" instead of just power.*

The bright switch or stand-by switch can each be jumpered (closed) if you don't want those on your build. Can leave out the power-on delay components if you don't want that.

I think I can still get this into a 1590B case. Easily into a 125B...


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## Paul.Ruby

Decided to add a soft-touch momentary footswitch toggling between mute and unmute. This gave me the chance to also make a toggle flip flop that always powers up muted. Schematic shows how to connect it to the existing design. C13 and the larger value of R19 than R18 provides the power-on skew to make the latch always turn-on muted. The toggle circuit might be finicky, but has worked so far with all the NPN types I have on hand. I suggest breadboarding with the exact transistors you will use to test that it toggles properly. The sketchy part of this is that it uses Q4 as if the collector and emitter can be interchanged, depending on which way the latch must be flipped. There is no such thing as a symmetrical BJT (that I know of). Q2 and Q3 can be just about anything. I've tested the following as Q4: 2N5088; MPSA20; MPSA18; 2N3903; 2N2222; A42; S9013; S9014; S9018; S8050. This circuit could easily have a relay added to make a soft-touch true bypass foot switch as well. I've seen microcontroller based boards that do this. No microcontroller needed and it powers up in a known state.

The power-on delay circuit provides ground to the toggle circuit in the schematic, so this is providing both features. "Belt and suspenders" this way. The power-on delay could be removed. Connect the line at the bottom of the toggle circuit to ground if omitting the delay.

The attached zip file has the ExpressPCB layouts of all three versions of the Volume-Only preamp and the toggle as it's own little board. Updated the PCB layout to bring both Q and Q-Bar to the edge. Schematic is also updated to show that I have the mute lines of the TPA3118 connected to Q-Bar instead of Q. After assembly, Q-bar powers up high. Has something to do with the slow power-on through the delay circuit. Anyway, the flip flop alone will always power up with Q high.




Made one by hand but also have a PCB layout attached.


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## Paul.Ruby

This is just a heads-up that the 100W boards that look like this are not 100W. They are not even TPA3116 chips. These use the 16-pin cheapo chips and these boards can only deliver about 43W into 4 ohm. See the 2nd picture below with the heat sink pulled... These work... And sound OK. But they not even as good as the smaller TPA3118 boards. This is the exact amazon link that sold me the fake version.


			Amazon.com


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## Paul.Ruby

EDIT: Verified PCB layout attached with a pair of mounting holes added.

Decided to make a a stand-alone circuit with an improved toggle flip-flop and power-on delay. Added Q5 to isolate the flip-flop from the circuits that are being controlled since that was messing with the flip flop operation. This allowed adding a stand-by LED. D1 is any diode. 1N914 will do. It keeps the 100k pull-down resistor on the TPA3118 from turning on the LED. ExpressPCB layout attached. The height of the board can fit along the side of a 125B enclosure. This will power-up in stand-by and won't allow coming out of stand-by for about 5 seconds.




Here's my first PCB under verification:



And planned mounting location...


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## zgrav

thanks for all of the updates as you are optimizing the build!


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## tcpoint

Here's another approach to the power on delay.  It was designed for a stereo headphone amp but solves the problem with a delayed relay. E12 circuit.


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## Paul.Ruby

tcpoint said:


> Here's another approach to the power on delay.  It was designed for a stereo headphone amp but solves the problem with a delayed relay. E12 circuit.


I'm considering some higher-power builds. This might come in handy. I may use a relay to disconnect the speaker output for amps without a mute. And, I will likely want the power-on delay to be unpowered if there is no speaker plugged in so that power-on delay starts when the speaker plug is inserted. I have 200W and 500W modules coming...  I built a 400W bass amp with high-end power-supply and amp modules. That one needs none of this because the amp itself handles all this gracefully. Those were expensive... I'm going to try some cheapos... I'm certain there will be nothing graceful about them.


----------



## Paul.Ruby

FYI, here's what my "full featured" build looks like. Volume-only preamp, bright switch, power-on delay, power-LED, stand-by-LED, toggle flip-flop, and soft-touch momentary foot switch. The toggle flip flop is the small board next to the foot switch. I'm keeping that 1" tall so it will fit on the side wall.


----------



## Paul.Ruby

Paul.Ruby said:


> EDIT: Verified PCB layout attached with a pair of mounting holes added.
> 
> Decided to make a a stand-alone circuit with an improved toggle flip-flop and power-on delay. Added Q5 to isolate the flip-flop from the circuits that are being controlled since that was messing with the flip flop operation. This allowed adding a stand-by LED. D1 is any diode. 1N914 will do. It keeps the 100k pull-down resistor on the TPA3118 from turning on the LED. ExpressPCB layout attached. The height of the board can fit along the side of a 125B enclosure. This will power-up in stand-by and won't allow coming out of stand-by for about 5 seconds.
> View attachment 23704
> 
> Here's my first PCB under verification:
> View attachment 23751
> And planned mounting location...
> View attachment 23752



FYI, updated post 149 above with a verified ExpressPCB layout for the stand-alone power-on delay and toggle flip flop for use with a soft-touch momentary foot switch that always powers up in a muted state. It's about 1.5" wide and 1" tall to be mounted with two stick-on nylon posts.


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## Paul.Ruby

Just tried using a Tone TwEQ version 1 from guitarPCB in comparison to the Cold Turkey from PedalPCB. These are very similar in design, sound and even the same size. Cold Turkey is easier to work with being only value changes. Tone TwEQ needs a cut on the board and different pots. The only notable difference of the Tone TwEQ is the three EQ pots in a row, if that is something someone really wants. 

I have several more boards coming from PedalPCB to try in the near future...

Here's the schematic to use Tone TwEQ with a TPA3118. R2 and R3 get the gain correct. R11 and R12 changed to reduce current draw. C9 and D1 are not needed and one of the holes for D1 is used for the added 470R, which forms the needed RC power supply filter with C8. R13 gets the LED current correct, if you're going to use the LED. Also consider adding a bright cap of ~680pf to the volume pot.


----------



## Paul.Ruby

Paul.Ruby said:


> This is just a heads-up that the 100W boards that look like this are not 100W. They are not even TPA3116 chips. These use the 16-pin cheapo chips and these boards can only deliver about 43W into 4 ohm. See the 2nd picture below with the heat sink pulled... These work... And sound OK. But they not even as good as the smaller TPA3118 boards. This is the exact amazon link that sold me the fake version.
> 
> 
> Amazon.com
> 
> 
> View attachment 23702
> View attachment 23701



The following version is real. The heat sink is screwed on, so easy to take off and put back on. No grease, so I'll be adding that... Also, although the mute signal is not brought out to a connector, it is easily accessible as it is routed on top over to R7 if control is desired.


			https://www.amazon.com/gp/product/B07PJKL334
		






EDIT: Trying out the real board... It has a simple power-on delay circuit attached to the mute pin. C4 is the delay capacitor. It instantly couples the 24V supply rail to the mute pin which is then discharged to ground.



Scope trace of the mute signal at power-on, using 10V as the supply for this testing. Red trace is the mute signal. Green is the output, relative to ground, which has some DC voltage when not on mute, so makes a nice marker for the un-mute timing. This is "good enough" for basic operation but not long enough on pedal boards with poorly behaving pedals. Since the components are easy to access, I will be removing C4 and R6 to connect the toggle-flip flop and 5-second power on delay. I will leave R7 (or jumper it) because the trace from there goes to the edge of the board where C4 is. That is a perfect spot to add a proper connector and pull-up resistor to power on in mute until unmuted externally.



Mute circuit changed to match the TPA3118 board with a super-glued connector. Once C4 is removed, there's plenty of room there for stuff.


----------



## Paul.Ruby

Paul.Ruby said:


> The following version is real. The heat sink is screwed on, so easy to take off and put back on. No grease, so I'll be adding that... Also, although the mute signal is not brought out to a connector, it is easily accessible as it is routed on top over to R7 if control is desired.
> 
> 
> https://www.amazon.com/gp/product/B07PJKL334
> 
> 
> 
> View attachment 23830
> 
> EDIT: Trying out the real board... It has a simple power-on delay circuit attached to the mute pin. C4 is the delay capacitor. It instantly couples the 24V supply rail to the mute pin which is then discharged to ground.
> View attachment 23853
> Scope trace of the mute signal at power-on, using 10V as the supply for this testing. Red trace is the mute signal. Green is the output, relative to ground, which has some DC voltage when not on mute, so makes a nice marker for the un-mute timing. This is "good enough" for basic operation but not long enough on pedal boards with poorly behaving pedals. Since the components are easy to access, I will be removing C4 and R6 to connect the toggle-flip flop and 5-second power on delay. I will leave R7 (or jumper it) because the trace from there goes to the edge of the board where C4 is. That is a perfect spot to add a proper connector and pull-up resistor to power on in mute until unmuted externally.
> View attachment 23855


FYI, post 159 above updated with info about the mute control of the real TPA3116 board.


----------



## Paul.Ruby

FYI, if all you want for the mute is a power-on delay for the TPA3118 board, this is the simplest possible. Gives about 5 seconds. Must use a 25V or higher voltage capacitor since it will be sitting forever at 24VDC once powered for 5 seconds. This method is not combinable with other forms of mute because you have to yank around the voltage on the capacitor to move back to mute. It will not mute fast nor will it unmute fast. Don't consider just adding a switch to bridge the capacitor, that will cause a spark internal to the switch and wear it out pretty quick and likely will cause an audible crack through the speakers prior to being muted. If you want anything more than power-on delay, use the the transistor circuit for it, which is easily combined with other methods of muting. I've fully settled on the toggle flip-flop and power on delay circuit as it's own board with a soft-touch momentary foot switch (post 149 above). It is working great with el-cheapo 2n2222 transistors in all spots.


----------



## Paul.Ruby

Since the TPA3116 board already has power-on delay, if you only want power on delay but want longer (about 5 seconds), remove R6 (under the heat sink, see post 156 above) and add a 22k resistor from ground to negative terminal of C4. Like this:


----------



## Paul.Ruby

Paul.Ruby said:


> FYI, if all you want for the mute is a power-on delay for the TPA3118 board, this is the simplest possible. Gives about 5 seconds. Must use a 25V or higher voltage capacitor since it will be sitting forever at 24VDC once powered for 5 seconds. This method is not combinable with other forms of mute because you have to yank around the voltage on the capacitor to move back to mute. It will not mute fast nor will it unmute fast. Don't consider just adding a switch to bridge the capacitor, that will cause a spark internal to the switch and wear it out pretty quick and likely will cause an audible crack through the speakers prior to being muted. If you want anything more than power-on delay, use the the transistor circuit for it, which is easily combined with other methods of muting. I've fully settled on the toggle flip-flop and power on delay circuit as it's own board with a soft-touch momentary foot switch (post 149 above). It is working great with el-cheapo 2n2222 transistors in all spots.
> View attachment 23914


Duh. Even simpler power on delay for TPA3118... Just solder in a cap.


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## Paul.Ruby

Have been comparing several versions of active EQ (Tone Tweq, Cold Turkey, Box 'n' all, 6-band) and keep going back to the volume-only preamp. There is something about the active EQ I don't like. It's a bit unnatural feeling in comparison. But I want a bit of tone control. So, I built a tried-and-true passive tone stack with Marshall values. This really feels right. Sounds right. It's a guitar amp. This includes an option for a bright switch but I'm going to build without the switch and use a 120pf bright cap (C4), leaving out the switch and C6. Spent the morning getting the tone stack and bright cap chosen just right. 



The expressPCB layout has two versions. I don't seem to be allowed to attach a zip anymore... ?? One with pots on copper side and one with them on component side. Building at home on single sided board makes the copper-side version very difficult to solder. I learned this the hard way, but I have one instance of that built up and in a case. Pictured here has the pots on the component side. This is easier to build but careful not to use components that are too tall. Note the 1uf cap laying on it's side and use of a surface mount electrolytic cap with it's base removed to make it through-hole. This will fit in a 125B case. I've ordered some right-angle header pins since can't use regular headers with this board. I might just hard wire this one. The LED resistor is not installed because every LED I try needs different current to get right. I still have LEDs from the 80s (I'm old) that draw 20 times more than this whole preamp... and modern super bright that seem to turn on if I get them near an outlet... Still too bright even with a 1M resistor.


----------



## stevel

I've been burned by those fake 100 watt boards too. Both from Amazon and Aliexpress. (I've been able to get refunds though, so I guess the sellers know they are scamming us). I had previously gotten a few that were real, and they look the same on face value but they certainly aren't. But those older boards are great. I ordered one of the boards with the screwed on heatsink  and will report back when it arrives.

I've been using these little amps (Blue 3118 boards and the previously purchased 3116 boards) connected to a 1x12 guitar cabinet as my main rehearsal amps for a while now. I drive them with either an HX Stomp, an Iridium, or recently, a NU-X Amp Academy. For gigs (there haven't been that many), I use a more powerful TDA7498e based board or even a pre-built amplifier based on those chips. 

I wish these sellers would provide proper specs (wattage @ impedance @ THD) instead of just quoting watts, but regardless, these TDA7498e boards are pretty loud. I built one from a baord, but I also have a few pre-built stereo HIFI amps based on these chips. I just use one channel, and they need conversioon cables (banana plugs on output and RCA or 1/8" on input), but for the money, they are hard to beat.

ex: Amazon link for 7498e amplifier


----------



## Willybomb

Well, we just played a gig on the weekend using the "100 watt" 3116 version as a bass amp to power a 4x10 cab using from a Helix.  These things are plenty loud (as we've all been saying) but seem to work best with a pedal/preamp feeding a buffer before the amp.


----------



## Paul.Ruby

Yes, these amps take line level. All of the methods I've posted above work well. And certainly need a good preamp as well. I use an AMT M2 as my preamp then the "volume only" version above on my pedal board. That's the core of the board. Been playing gigs continuously with these.


----------



## Mike McLane

Anybody have misgivings about using these boards for serious gigs?  Was it earlier on this thread or another where the TPA3118 (max 24vdc) was sporting 25V caps that burned up.  Can you really get a hold of a board that has some "umph" to it?  Also, Chuck Bones had a fairly thoughtful piece about the fact that all power supplies are not created equal.  That something for this situation (like the TPA board itself) needs to be carefully chosen.  Just because your laptop psu puts out 19vdc @ 3+amps doesn't necessarily make it ideal for this.  I've been looking at the ICEPower boards which, while much more expensive are also MUCH stouter. . . . with power supplies, buffers, etc. already designed for and integrated on the boards.  Look to be pretty close to plug and play.  Same units as used in the Seymour Duncan PowerStage and Fender Tonemasters.


----------



## Paul.Ruby

The other guitar player in my band and I have been doing it regularly. I drop a 24V supply down to 23V with a series diode (it's posted in this thread) and I used and oscilloscope to show my supply has no overshoot and is well behaved. No problems... Also, I've been using the 24V output of my cioks DC7, which is awesome.


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## Paul.Ruby

I should add... Since these are easy to build and small, we have spares... Just in case. And, I made the guts modular so it's easy to swap a board if needed.  That's all shown in my posts above...


----------



## Robert

Not sure if it has been mentioned previously in the thread, but this isn't much different from how the Friedman BE-Mini works.


----------



## Mike McLane

I'm not an electronics guy. I just want a 125B PCB that I can assemble then plug in and go.  All of this stuff looks and sounds great, but I don't have the technical chops for it.  Mr. PedalPCB initially teased us with this. . . . .





That's what I'm lookin' for.


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## fydo

My TPA3118 arrived today and I am excited to see what is possible with it. Watching this thread, for sure!


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## Robert

I couldn't get the correct 1/4" jacks for a while (they have to be Neutrik, the clones wont work) so I put this _back _on the backburner....

Maybe they're available now, I'll have to go check.   That's really our only hold up.


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## Paul.Ruby

Mike McLane said:


> I'm not an electronics guy. I just want a 125B PCB that I can assemble then plug in and go.  All of this stuff looks and sounds great, but I don't have the technical chops for it.  Mr. PedalPCB initially teased us with this. . . . .
> 
> View attachment 28723
> 
> That's what I'm lookin' for.


Want to buy one of the ones I made? I have... Many... Because I was comparing different preamps.


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## Elijah-Baley

Meanwhile, I received my first TPA3118.
I guess I have to wait the end of the summer to test it: power up with a 1-spot 1700mA PSU and then another cheap PSU for pedal, a RockPower 18v 2000mA. I'll use a 15w 8" speaker.

Are there any risk of damage something with those stuff?


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## temol

Before connecting the module to the speaker I'd user 100W 8R resistor as a load and measure output power (with oscilloscope).
15W RMS equals around 15.5V p/p (into 8R load). But it's pure sinewave. If you clip the signal (in preamp or by overloading input of the amp) then clipped 15V p/p is no longer 15W RMS. 15V squarewave = 28W RMS. 60W RMS equals  31V p/p (8R load).


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## Mike McLane

Roberto - Will the PCB you're doing accommodate the 3116 or other higher powered modules?   I play bass fairly often and would love something that will do for a small club.


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## Robert

Mike McLane said:


> Roberto - Will the PCB you're doing accommodate the 3116 or other higher powered modules?   I play bass fairly often and would love something that will do for a small club.



I'm not sure, I haven't looked at the 3116.     My initial guess is probably not as a direct plug in replacement.


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## Mike McLane

First things first.  If you can get the 3118 flying I'm good.  Having 100W @ 8 ohms would be probably be great for a small bass rig, but the 3116 @ 50W @ 8 (?) ohms would probably suffice as well.


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## Elijah-Baley

Elijah-Baley said:


> Meanwhile, I received my first TPA3118.
> I guess I have to wait the end of the summer to test it: power up with a 1-spot 1700mA PSU and then another cheap PSU for pedal, a RockPower 18v 2000mA. I'll use a 15w 8" speaker.
> 
> Are there any risk of damage something with those stuff?


I forgot, but the speaker is 8 Ohm.



temol said:


> Before connecting the module to the speaker I'd user 100W 8R resistor as a load and measure output power (with oscilloscope).
> 15W RMS equals around 15.5V p/p (into 8R load). But it's pure sinewave. If you clip the signal (in preamp or by overloading input of the amp) then clipped 15V p/p is no longer 15W RMS. 15V squarewave = 28W RMS. 60W RMS equals  31V p/p (8R load).


Thanks, but I'm lost, a bit.
Anyway, I didn't have any 100W 8R resistor, I don't have the oscilloscope.
I thought to test the power amp with the guitar directly into it, and the speaker at the output.

I checked again the datasheet, maybe I asked it before, but as I remember at 9v my speaker should be safe. At 18v I should avoid higher volume, because the wattage at 18 is close to 20w.
This is about the speaker.
What about the mA of my two PSU? The 9v with 1700mA and the 18v with 2000mA?
If I'm not mistaken, the mA consumption should be relatively low, right?


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## Robert

Mike McLane said:


> First things first.


Looks like the jacks _are _back in stock at Mouser.  I'll get the ball rolling on this again.


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## temol

Elijah-Baley said:


> Anyway, I didn't have any 100W 8R resistor, I don't have the oscilloscope.
> I thought to test the power amp with the guitar directly into it, and the speaker at the output.



There's a safe way, and your way. You have to choose 
You can keep the volume down but one day someone can crank the knob to the max and then what?

Soundcard oscilloscope software https://www.sillanumsoft.org/prod01.htm
 google "soundcard oscilloscope probe"

Btw - the measured value is relative. To calibrate the probe you need a reference signal, with known level. Also - if you have a probe with two diodes at the input - they would clip if the signal exceeds diode fv (0.6-0.7V for the 1N4147). So if the input signal is greater than 0.7V you have to adjust input potentiometer/trimmer (voltage divider acting like VOL pot) to bring the signal below the clipping threshold. Each change of the "sensitivity" requires re-calibration.


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## Elijah-Baley

I prefer the safe way. But I see several TPA3118 building with no big wattage resistor. 



temol said:


> Before connecting the module to the speaker I'd user 100W 8R resistor as a load and measure output power (with oscilloscope).



This big resistor is just to use this amp with oscilloscope or I need it if I use the amp with a speaker to play the guitar?

I found these:
- 6.8 Ohm http://www.banzaimusic.com/6-8-ohm-100w-wirewound.html
- 10 Ohm http://www.banzaimusic.com/10-ohm-100w-wirewound.html

Thank you, I'll take a look to the link, trying to understand what it is.

I really don't know when, but once I built this power amp properly (I still don't know the form: pedal, just power amp, mini head with some preamp, easy, complex...) I'll use a good speaker. I could to buy a cheap, but good, 12" guitar cabinet (my 8" is a cheap guitar speaker in a wood box!). Or, initially, and if I can use it safely, I could to connect this amp to one or both speakers on my 120w Crate amp.
Then I need even a good PSU, I guess. The RockPower 18v 2000mA I mentioned before... Do you think it's ok? I never used it, just because I noticed that was a bit noisier then my old red label Boss PSU.
For this amp I thought to buy an used laptop PSU, if I'm lucky it will be cheap and, most important thing, noiseless.


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## temol

Big resistor is a dummy load, only for testing/measuring purposes. You're going to use 60W module with 15W speaker. So in my opinion it's good to know how far you can push it before you damage the speaker. 2A PSU seems to be enough, especially that you're not going to push it to the max. But you'll see everything when testing. Just measure current draw.

Ebay listings for  8R, 100W resistor.


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## Bazmatron

Hey All, 

First post loving the thread. 

Question? 

I'm using a 50k pot as my volume control... and even all the way up its really quite.

When i remove the volume pot and connect it direct to a pedal..... wow... this thing is so loud. 

I tried a 10k pot and didn't get any sound... amy ideas? 

Cheers Baz


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## Paul.Ruby

Bazmatron said:


> Hey All,
> 
> First post loving the thread.
> 
> Question?
> 
> I'm using a 50k pot as my volume control... and even all the way up its really quite.
> 
> When i remove the volume pot and connect it direct to a pedal..... wow... this thing is so loud.
> 
> I tried a 10k pot and didn't get any sound... amy ideas?
> 
> Cheers Baz


These amps take line level (about 2V peak to peak) for full volume. Guitars and pedals are instrument level (about 200mV peak to peak). You must use some sort of preamp that will get up to line level. I've posted multiple solutions in this thread.

Edit: Oops, I misread your question. You have the pot connected wrong... Draw up what you have done and post some pictures.


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## Bazmatron

Cheers for the reply.

I just followed the diagram with the 50k pot aand cap on page 2 or 3. Was very strange. 

Not sure if there was an issue with amp module so im checking that out now.

Is there any reason it would be low with the pot connected? 

From what I've read people use a dual buffer with a volume control so going to try that


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## zgrav

Try a pot with more resistance instead of lower resistance.


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## Willybomb

You need a buffer in front of these boards somewhere along the line, I put one before and after the volume pot.  You'll get a great result using a buffered pedal, but no so much if you plug straight into it.


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## 80k

Really looking forward to seeing some projects with this board. I bought some fake TPA3118 (28 pins instead of 32 pins) from Aliexpress. They work surprisingly well, but I would love to have a legit source, so looking forward to its availability from PedalPCB. 

Has anyone heard when they will have them back in stock? I'll be order a few to replace my fake ones as soon as they are available. 

BTW, for those who don't have the isolated Neutrik jacks, I had success using those isolation washers (with the sleeve) with regular mono jacks. I just had to drill it to 7/16" (instead of the usual 3/8") to fit the isolation washer from the inner side. I also used a regular nylon washer on outer side, but can confirm that isolates the jack just fine.


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## Elijah-Baley

After I read your post I checked my TPA3118 PCB I bought from ebay. It's still close in the bag because I didn't try it. It has 28 pin, so it's a fake!
What's the difference? It will work good as the genuine one? Max voltage, watt, noise, distortion...

In an electronic forum I found this:

Guy 1: Any idea what these chips actually are? It's a 28-pin SSOP package, and can handle a 21V rail just fine. They sound terrible but I guess that's expected for a fake, remarked chip. These are sold on Amazon (India) for just under $5 each. Interestingly the listing shows the correct PCBs, but this what you get in the package.
    I want to reduce gain and/or try PFFB to improve things, as someone who's using a remarked $2 chip will be using inductors below the bottom of the barrell. I soldered the headers and thus can't legitimately ask for a return, but I wasn't expecting fakes so I didn't pay much attention.

Guy 2: Those are TPA3110 chips (or some Asian equivalent).
I had the same issues. Check couple of page back in this topic.
There is a little error in the board, just connect pin 5 and 6 to ground and your board will be nice and quiet! 
(ground should be on pin 3 and 4 if I am not mistaken, but pls double check)


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## 80k

Elijah-Baley said:


> After I read your post I checked my TPA3118 PCB I bought from ebay. It's still close in the bag because I didn't try it. It has 28 pin, so it's a fake!
> What's the difference? It will work good as the genuine one? Max voltage, watt, noise, distortion...



Funny, last night, I was actually just reading the same comments on the electronics forum you quoted from!

So I boxed one of these fake ones up a couple days ago:

I do believe these are lower wattage/output. Based on what I read about the genuine chips, I expected this to be louder.
There is some hissing if I attempt to use a volume pot to lower the volume using the wiring diagram that has been floating around (on the TheGearPage). No buffer, but simply a 50k log pot going into the input (with a 220nF cap in series), and the other wiper going to ground. I am sure I did the wiring correctly. The hissing problem goes away if I dime the volume knob and control the volume with my preamp pedal. I'm guessing that a genuine chip wouldn't have this problem due to the number of people happy with the results with that wiring diagram.
Overall, if I use it with volume knob dimed and control the volume from the preamp, it sounds really good. Lower volume than I expected, but it is clean headroom for driving a cabinet for home practice and light rehearsals.
I looked at pins 5 and 6 after reading that post and it doesn't appear to be floating on mine and it wasn't obvious that I should be connecting them to ground. I honestly don't trust the smallest soldering tip I have to be able to solder anything to those pins without damaging the chip, so I will likely just leave it alone.
I'll be replacing it with a genuine board as soon as I find a source, or whenever PedalPCB gets them in stock!


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## tcpoint

What power jacks are you using?  The power supply I have is rated at 24 volts and 3 amps.


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## Paul.Ruby

tcpoint said:


> What power jacks are you using?  The power supply I have is rated at 24 volts and 3 amps.


2.5mm center-pin. Center positive. Can be isolated or not... I've used these:


			https://www.amazon.com/gp/product/B07Y8KKSR1
		


Of course, make sure your power supply is center positive, too... And I strongly recommend a 1N5408 in series with the 24V in case your power supply overshoots. Even a little can blow the caps.


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## tcpoint

I got a bunch of those from my headphone amplifier days.  Thanks.


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## Willybomb

I'm cutting the ends off my laptop power supplies and replacing them with 2.1mm, wired to center negative.


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## Mike McLane

I thought I saw a comment from Chuck Bones many moons ago re: a level of caution using any ol' computer laptop PSU for these.  Is this simply a matter of having plenty of current to deliver that extra umph when needed?  Are there any guidelines we can look to in purchasing an adequate PSU?  How about one of the Mean Well PSU's Parts Express sells for powering Class D boards?  They're not that expensive for a 5A PSU?


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## stevel

Mike McLane said:


> I thought I saw a comment from Chuck Bones many moons ago re: a level of caution using any ol' computer laptop PSU for these.  Is this simply a matter of having plenty of current to deliver that extra umph when needed?  Are there any guidelines we can look to in purchasing an adequate PSU?  How about one of the Mean Well PSU's Parts Express sells for powering Class D boards?  They're not that expensive for a 5A PSU?


I’ve used actual laptop power supplies and inexpensive generic laptop “style” power supplies from Amazon with no issues at all. Just have to make sure the polarity and size of the plug is correct. I sometimes just cut off the plug and solder the proper on on. And then I use a label maker to stick on a label describing the new polarity so that I don’t have to guess or measure.


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## Paul.Ruby

Mike McLane said:


> I thought I saw a comment from Chuck Bones many moons ago re: a level of caution using any ol' computer laptop PSU for these.  Is this simply a matter of having plenty of current to deliver that extra umph when needed?  Are there any guidelines we can look to in purchasing an adequate PSU?  How about one of the Mean Well PSU's Parts Express sells for powering Class D boards?  They're not that expensive for a 5A PSU?


The most concerning thing is the 25V caps on the amp. A cheapo supply might overshoot or not be fully stable at 24V. I've had good results from several different cheap 24V supplies from amazon but I include a 1n5408 diode in series with the supply voltage inside the amps I've built. None have been a problem. The only issue I've had is to use an ungrounded power supply (two prong, not 3-prong). The grounded ones form a ground loop with my pedal board and hummmmmmm.


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## RetiredUnit1

I just received this a few days ago.  It comes unassembled so you don't have to use the faceplates unless you want, but it has bluetooth in.  Tried it, pretty loud.  Not sure what I'm going to do with it yet but I was thinking along the lines of a stereo chorus amp powered with a bunch of 18650's.  One 5s sled would yield around 20vdc 2.2AH.  Wire a few more in parallel for days of busking without a charge....  







*(edited:  here's the watts/input power/ohms data for this.  I have some 100w 4ohm celestions I can pop in....)*


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## Willybomb

Hopefully the caps are a bit better at handling 24v.  The ones on the little 60w modules *say* 35v iirc, but will blow at 24.
I doubt these are 100w.  I've been running mine at 19v, its ok.  Might try one of these out, as I have a couple of higher power laptop supplies to try.


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## Paul.Ruby

Willybomb said:


> Hopefully the caps are a bit better at handling 24v.  The ones on the little 60w modules *say* 35v iirc, but will blow at 24.
> I doubt these are 100w.  I've been running mine at 19v, its ok.  Might try one of these out, as I have a couple of higher power laptop supplies to try.


The 100W amps have 35V caps that I've seen. The 60W amps that I have are all 25V caps:


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## Willybomb

Either/or.  Those 60watters blow at @24v.


----------

