# Tube preamp (do I dare bring up modelers!?!?!?)



## Mike McLane

The whole Ukraine thing has brought up the tube sourcing saga and suggests the eventual death of tube amps as the predominant force in the guitardom. I wonder about a tube driven preamp as a front end to a modeler setup to impart some "tubiness".  Not an OD pedal, but something along the line of a mic preamp. 1) Would it really help the situation? . . and. . . . 2) could you basically get the same thing from a well designed FET circuit (which might suggest that there are already a couple of candidates in the PPCB stable)?


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## vigilante398

Tube preamps are kind of my thing, and putting a clean tube preamp in front of a modeler is probably the #2 most common way people seem to use the ones I make. #1 is skipping the modeler and going straight from the tube preamp into an IR loader over to FOH.

Could this be done just as well with a FET circuit? To some degree sure, but if you're looking for tube tone, you'll be hard-pressed to get something satisfying without a tube.


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## Funnel

I’m not sure if you watch That pedal show, but they did an episode on preamp pedals. Though they used a power amp and speaker cab opposed to direct in or an ir loader. They used the d&m drive, gladio, broadcast, and benson preamp. And they put them against Kingsley pedals that are designed to be a preamp. It’s worth a watch or at least jump around to the pedals you may be curious about. 




@vigilante398 I’ve never owned a tube pedal. Though I have been interested in them. and keeping with the theme of the discussion, how often do tubes in preamp pedals have to be replaced? While I don’t love the idea of not having an amp, I also know that if I want to play live many places are demanding a silent stage. So this seems like a good alternative.


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## vigilante398

Funnel said:


> @vigilante398 I’ve never owned a tube pedal. Though I have been interested in them. and keeping with the theme of the discussion, how often do tubes in preamp pedals have to be replaced? While I don’t love the idea of not having an amp, I also know that if I want to play live many places are demanding a silent stage. So this seems like a good alternative.


I mean if you run them constantly and never unplug them you may have a tube fail in 10 years or so, but I feel like the general answer I can give is "almost never". Preamps are not generally super hard on the tubes, so a preamp tube in a typical preamp pedal should last just about forever. If someone tells you that you need to "change them regularly for best results" they're probably trying to sell you tubes.


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## Harry Klippton

vigilante398 said:


> Tube preamps are kind of my thing, and putting a clean tube preamp in front of a modeler is probably the #2 most common way people seem to use the ones I make. #1 is skipping the modeler and going straight from the tube preamp into an IR loader over to FOH.
> 
> Could this be done just as well with a FET circuit? To some degree sure, but if you're looking for tube tone, you'll be hard-pressed to get something satisfying without a tube.


Silicon can sound _just like_ germanium


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## Mike McLane

Yeah, I know about the Kinglsey pedals.  Saw the TPS vid and the Kingsley is a thing of beauty.  Would LOVE PPCB to design a Squire look alike. As to my application, I was thinking about the Page which is an OD type thing, but not a full bore preamp with EQ, etc. Pretty much just a gain and volume control with a (hopefully) flat response simply to sweeten the sound. Something akin to the Six String Stinger except tube driven. As to Vig398's point, if PPCB would uncork a TPA3118 unit I'd put that with a Squire type pedal and walk away a happy man! Hey Vig398, where can I see your stuff??


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## JamieJ

We definitely need a @vigilante398 and @PedalPCB tube driven preamp collab! 

Is all this tube shortage talk just a temporary issue like we have seen with ICs or is this going to be a permanent issue?


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## Mike McLane

If there's a market for tubes they'll get built.  There's tons of hi fi audiophiles out there that use 'em, too.


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## Barry

Seems somebody did that a few years back, as I recall it was a collaboration between line 6 and another amp builder, it may have been modeler in front of tube power section, been too many years and beers


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## vigilante398

Mike McLane said:


> Yeah, I know about the Kinglsey pedals.  Saw the TPS vid and the Kingsley is a thing of beauty.  Would LOVE PPCB to design a Squire look alike. As to my application, I was thinking about the Page which is an OD type thing, but not a full bore preamp with EQ, etc. Pretty much just a gain and volume control with a (hopefully) flat response simply to sweeten the sound. Something akin to the Six String Stinger except tube driven. As to Vig398's point, if PPCB would uncork a TPA3118 unit I'd put that with a Squire type pedal and walk away a happy man! Hey Vig398, where can I see your stuff??


You can see my current stuff on my website https://www.sushiboxfx.com/product-category/pedals/ I also have a dedicated thread on Talkbass where I spend WAY too much time because 99% of my customers are bassists. It turns out if you find a group that's largely been neglected by pedal makers and do something specifically for them they react positively 



JamieJ said:


> We definitely need a @vigilante398 and @PedalPCB tube driven preamp collab!
> 
> Is all this tube shortage talk just a temporary issue like we have seen with ICs or is this going to be a permanent issue?


I used to do a Kingsley Harlot (v2) clone, but I discontinued it as I'm trying to focus more on original circuits and less on clones. I would be more than happy to share schematics and ideas if @PedalPCB wanted to pick up the Harlot or something similar. My design fit in a 125B but it was all surface mount. If you use a PCB-mounted tube socket and have the tube stick out the top of the enclosure it would free up enough space that you should be able to fit the rest of the circuit in there though. Just a thought.

As for tubes, I expect it to be temporary. It smelled to me like an EHX cash grab from the beginning, create demand while using the excuse to drive up prices at the same time, then yesterday EHX announced that they worked everything out and will be getting more tubes, and urged everyone not to cancel their backorders. I didn't buy Russian tubes before this, I don't plan to buy them after. JJ has always been good for me, and I plan to stick with them.

One of the main reasons no new companies are coming up to build tubes is equipment. Psvane is the newest tube company I'm aware of, they make expensive hi-fi tubes, but they were able to set up shop by buying out an old retired factory and using the equipment that was already there. JJ is the newest common tube manufacturer, and they set up shop with the old Tesla manufacturing equipment (thus JJ/Tesla). Nobody makes the machines to make tubes anymore, so if you want to start from scratch you're going to have to design and manufacture the machines that do the building. HUGE up front cost for a niche market.

Another frequently cited reason is environmental regulations. Manufacturing tubes is not a super environmentally friendly process due to the materials and processes involved, so they're currently only made in countries that don't have strict environmental regulations. This is, in my understanding, one of the big contributing reasons for the USA tube factories shutting down.

Anyway, my $0.02.


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## Robert

vigilante398 said:


> As for tubes, I expect it to be temporary. It smelled to me like an EHX cash grab from the beginning, ...



Yep, this isn't the first time EHX has mentioned a tube shortage in the past year.









						“There is a worldwide panic on availability of vacuum tubes”: EHX's Mike Matthews on the murky future of valve amps
					

EHX founder Mike Matthews has sounded an ominous warning about the present and future of amp tube production.




					guitar.com


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## Feral Feline

vigilante398 said:


> My design fit in a 125B but it was all surface mount. If you use a PCB-mounted tube socket and have the tube stick out the top of the enclosure it would free up enough space that you should be able to fit the rest of the circuit in there though. Just a thought.



Personally, I hate* tube-pedal designs that stand the tube upright in the enclosure, exposing the tube to potential eventual harm.

One of the reasons for your  Sushibox’s success, I’m sure, is the properly-packaged tubes — and may you have continued success, sir.


There are others on this forum that have no problem with pointing tubes at the sky, that is their prerogative.
I’d rather go to 1590BB and secure tube inside than have a 1590N1 with a sacrificial tube-altar.



* (“hate” may not be strong enough… “loath”, “despise”, “vehemently oppose”, “disgusted by”, “#%*^@”… hmmm 😼)


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## Mike McLane

I ran across this "nutube" thing in relation to the Vox MV50's (which I had never heard about).  I Googled Noritake (the developer) and discovered that its not a Vox proprietary thing.  In fact if you go here .  .  .  . http://nutube.us/ .  .  .  .  or here .  .  .  . https://diyaudiostore.com/products/korg-nutube .  .  .  . they're making it available to DIY'ers for discovering alternate uses.  VERY INTERESTING.


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## Robert

Mike McLane said:


> I ran across this "nutube" thing in relation to the Vox MV50's



Yep, we have a PCB for a NuTube based overdrive.








						NuDrive - PedalPCB.com
					

Korg NuTube Based Overdrive




					www.pedalpcb.com


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## jubal81

Funny this came up. I recently met up with a guy who has a Fuchs ODS and we A/B tested the ODS submini tube preamp pedal I made using the Fuch's loop return.
We both thought the pedal preamp actually sounded just as good, if not a bit better! I'm suspicious the depletion mode, high -voltage Mosfet buffer output on the pedal had something to do with it.

I run it into a Two Notes Cab M+ for headphone playing and going direct and it's a great setup.

The only downside is now I want to do a 4-tube design with a Dumble clean channel on one side and an SLO preamp on the other, lol.


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## Mike McLane

So if the nutube technology performs as well as a 12AX7. . . . GREAT!  Otherwise stay with 12AX7 technology.  *That said. . . . when do we get the PCB??*  I vote for simple straightforward Fender BF-like pedal (AB763).   Now you have a great pedal platform for all your PPCB gear.


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## DAJE

Mike McLane said:


> I ran across this "nutube" thing in relation to the Vox MV50's (which I had never heard about).  I Googled Noritake (the developer) and discovered that its not a Vox proprietary thing.  In fact if you go here .  .  .  . http://nutube.us/ .  .  .  .  or here .  .  .  . https://diyaudiostore.com/products/korg-nutube .  .  .  . they're making it available to DIY'ers for discovering alternate uses.  VERY INTERESTING.


I have a Vox MV50 Clean which I love. I have the matching 8-inch and 12-inch speaker boxes, too. If I was doing serious gigging I'd probably buy another one and run them in stereo.


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## Username123

Barry said:


> Seems somebody did that a few years back, as I recall it was a collaboration between line 6 and another amp builder, it may have been modeler in front of tube power section, been too many years and beers


It was Bogner Amplification who collaborated with line 6. One day I randomly saw that on reverb while I was looking for another amp.


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## vigilante398

Feral Feline said:


> Personally, I hate* tube-pedal designs that stand the tube upright in the enclosure, exposing the tube to potential eventual harm.
> 
> One of the reasons for your  Sushibox’s success, I’m sure, is the properly-packaged tubes — and may you have continued success, sir.
> 
> 
> There are others on this forum that have no problem with pointing tubes at the sky, that is their prerogative.
> I’d rather go to 1590BB and secure tube inside than have a 1590N1 with a sacrificial tube-altar.
> 
> 
> 
> * (“hate” may not be strong enough… “loath”, “despise”, “vehemently oppose”, “disgusted by”, “#%*^@”… hmmm 😼)


Yeah I don't like the tubes up top either. I appreciate the space savings, and it can be a neat look with glowing tubes sticking up like a hot-rodded Camaro, but they belong safely tucked inside the pedal in my opinion. My typical mounting method is a bit of a pain, though I do have one other mounting method I tried out and it works fine, I've considered throwing together a project with that method, but my regular builds (and my day job, and my wife, and my kids, etc) have kept me busy enough that I haven't gotten around to casual PCBs for the DIY-ers.



Mike McLane said:


> So if the nutube technology performs as well as a 12AX7. . . . GREAT!  Otherwise stay with 12AX7 technology.  *That said. . . . when do we get the PCB??*  I vote for simple straightforward Fender BF-like pedal (AB763).   Now you have a great pedal platform for all your PPCB gear.


Nutubes are okay, I'm not a fan. If you look through the Nutube-based schematics on the internet you'll be hard-pressed to find one with 100% tube signal path, they always have something solid-state in front of them pushing them. This is because Nutubes have a ridiculously low amplification factor (mu), They don't drive very well on their own. The extremely low power requirement is awesome, but the sound makes it not worth it in my opinion.


TubeAmplification Factor (µ)12AX710012AT76012AU720Nutube 6P114.5


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## Mike McLane

OK, its settled then. . . we go with the 12AX7.  When do we get started?


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## Mike McLane

OK.  I know almost nothing about electronics, but I put together a preliminary layout for an AB763 circuit board based on a number of schematics I pulled up and am hoping I can get some coaching on it.  It has an added Mid control as well as an EQ Lift component to it.  The big issue for me is the power supply which I'm powerless (ha ha) to design.  We can delve into power if I get some basic interest from you guys in debugging this circuit layout.  Also, I forgot to indicate the value of the pots, but they're standard Fender values (Mid pot is A10K, EQ pot is A250K) The components show are to scale (looked up the specs) and they are shown mounted on a 2.25" x 2.25" board.  Working out the enclosure and location of the pots and tube socket would come after finalizing the circuit board and power supply.  Had a couple of specific questions denoted by asterisks 1 & 2 (don't worry with 3 for now).  #1 - Most amps have a 120pf bright cap in the area shown on the Gain pot.  Should there be one left there or should it be moved to the Volume pot?  Also, as guitar players most of us install a treble bleed circuit (cap & resistor in parallel) across our volume pots to accomplish the same thing and it works much more seamlessly than this all-or-nothing approach of the switched cap? Why can't we do that here?  #2 - This would be a footswitch instantiating the EQ Lift, the EQ pot determines the amount of "lift".  That results in a marked increase in volume, but Kingsley puts a pot on his pedals to control that.  Could that be done by placing a standard volume control pot in between the Mid pot and the foot switch?  If so, what value?


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## HamishR

The first OD pedal I ever used for gigging was a Matchless Hotbox. It was basically a Vox preamp in a (very large) pedal. Then I got a Matchless Dirtbox, then a Bad Cat Two-tone. I used the Two tone for ages because it sounded extremely natural and amp-like and i could stick a delay after it and run it into a non-MV amp. 

Then one day I discovered that a good SS pedal could sound just as good. I went through various Jfet overdrives and finally now I build my own ODs. I only recently sold my Bad Cat Two-tone after blind testing it with a couple of trusted op-amp & diode pedals. Bad Cat and Matchless run the tubes at quite high voltages so they do actually wear out, unlike the tubes in Kingsley pedals. I've had a few Kingsleys and they really were excellent but (a) bigger than I needed and (b) sound a bit jazz-fusion for me.

I used to think that only tube distortion was good enough. Now I know that's not true, for me, anyway.  But I still love a tube amp!


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## vigilante398

Mike McLane said:


> OK.  I know almost nothing about electronics, but I put together a preliminary layout for an AB763 circuit board based on a number of schematics I pulled up and am hoping I can get some coaching on it.  It has an added Mid control as well as an EQ Lift component to it.  The big issue for me is the power supply which I'm powerless (ha ha) to design.  We can delve into power if I get some basic interest from you guys in debugging this circuit layout.  Also, I forgot to indicate the value of the pots, but they're standard Fender values (Mid pot is A10K, EQ pot is A250K) The components show are to scale (looked up the specs) and they are shown mounted on a 2.25" x 2.25" board.  Working out the enclosure and location of the pots and tube socket would come after finalizing the circuit board and power supply.  Had a couple of specific questions denoted by asterisks 1 & 2 (don't worry with 3 for now).  #1 - Most amps have a 120pf bright cap in the area shown on the Gain pot.  Should there be one left there or should it be moved to the Volume pot?  Also, as guitar players most of us install a treble bleed circuit (cap & resistor in parallel) across our volume pots to accomplish the same thing and it works much more seamlessly than this all-or-nothing approach of the switched cap? Why can't we do that here?  #2 - This would be a footswitch instantiating the EQ Lift, the EQ pot determines the amount of "lift".  That results in a marked increase in volume, but Kingsley puts a pot on his pedals to control that.  Could that be done by placing a standard volume control pot in between the Mid pot and the foot switch?  If so, what value?


Looks good to me  You could add in the cap in #1 if you want, but I leave them off in my designs personally. No idea what value pot for #2, I would start with maybe 10k or so?


HamishR said:


> Bad Cat and Matchless run the tubes at quite high voltages so they do actually wear out, unlike the tubes in Kingsley pedals.


I can't speak to Bad Cat as I've never poked around one in person, but Matchless and Kingsley both run their pedals internally at about 250V (the Matchless I measured was closer to 240V, Kingsley was exactly 250V). Matchless does it with a transformer and Kingsley does it with an SMPS, neither is harder or gentler on tubes than the other. Not sure where you got that.


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## Mike McLane

HamishR . . . I'm not looking to do an OD pedal, but a straight-ahead tube preamp to run into a power amp of some kind for a good clean Fenderish platform.  I realize it could be used as an OD into the front end of an amp, but that's not where I was intending to go.

Vig398 . . . I was waiting for you, buddy!  Thx for the reply!  Re #1: I can see the non-necessity of the bright cap because as a stand-alone preamp (where your output volume is determined by the power amp) you're going to keep the Gain cranked up where it sounds best, hence, no need to be concerned with a bright cap.  I assume that's the gist of what you're getting at.  Re #2:  Roger that.  Now comes the fun part . . . the power supply.  I notice in the Harlot shots in another thread that it's built against the side of the enclosure. . . I see a couple of voltage regulators. . . but that's ALL I know.  Kingsley uses a 9vdc/500mA source, Tubesteader uses 12vdc/300mA.  I would think 9vdc would be more compatible with pedal power units.  Any interest in helping out with a layout for a power supply daughter board?


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## vigilante398

Mike McLane said:


> Now comes the fun part . . . the power supply.  I notice in the Harlot shots in another thread that it's built against the side of the enclosure. . . I see a couple of voltage regulators. . . but that's ALL I know.  Kingsley uses a 9vdc/500mA source, Tubesteader uses 12vdc/300mA.  I would think 9vdc would be more compatible with pedal power units.  Any interest in helping out with a layout for a power supply daughter board?


I'm not going to pretend to be an expert, but I wrote this up a little while ago, gives a decent starting point if you want a bit of reading. https://forum.pedalpcb.com/threads/tubes-102-intro-to-power-supplies-for-tube-circuits.10652/

I would be more than happy to help with a power supply board layout. I'm actually putting together a PCB order today, I could throw something together for SMD pick-and-place and get some if you want something ready to go. Or if you prefer to do it yourself I could help out with a through-hole layout.


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## vigilante398

You took longer to answer than it takes for me to do layouts, so I threw together an SMD board and a through-hole board.


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## Mike McLane

I'm thinking thru-hole. . .  a pre-drilled circuit board (or a blueprint for diy) with layout diagram and a parts list that hobbyists like me can order and assemble.  However, if you think SMD is simpler, cleaner, more compact, etc. (and that we hobbyists need to learn to deal with soldering SMD components at some point) then I would follow whatever rec you had.  The point is to make it reasonably doable for dumb shits like me  ("MIRDFDSLM"). I read thru your tube thread and I'm re-thinking the supply voltage thing given that a 12vdc probably simplifies wiring/component requirements on the heater leg of the power supply daughter board. . . MIRDFDSLM. But how does 12vdc power input complicate things when everything else is 9vcd? I don't want to have to get a complicated (read: expensive) power supply.

The whole point of this exercise for me is a DIY (read: inexpensive) tube driven, light weight/portable rig for a working musician (read: broke) for a modern "PA driven" venue. This preamp can't be that expensive, neither would a simple Class D power amp & power supply. Build your own 1 x 12" speaker cab ($50) and load it with your speaker of choice ($100).  You're looking at having a BF Deluxe pedal platform for a few hundred bucks.  Throw in a few PPCB pedals. . . stick an SM57 in front of it and you have a GREAT gig rig.  And its much simpler, uncomplicated and more "bullet proof" than a modeler.


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## Mike McLane

Sorry.  Spent so much time contemplating my navel that I didn't see your follow up post.  YooDaMan!!!  Would the thru-hole be a pre-printed PCB or would those be eyelets for "hard wiring"?  Also, I see you went with 9vdc input.  Great!!


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## vigilante398

Mike McLane said:


> Sorry.  Spent so much time contemplating my navel that I didn't see your follow up post.  YooDaMan!!!  Would the thru-hole be a pre-printed PCB or would those be eyelets for "hard wiring"?


It's a through-hole fabricated PCB, no eyelets or hand-wiring necessary. It will be very similar to the way Kingsley does it.

The pre-assembled SMD boards are neat, but since the MOSFET and 6V regulator are mounted flat on the board it works out to be the same size as the through-hole board. But I like SMD, and it's only an extra few bucks to get the boards assembled at the factory, so no hand-soldering SMD components necessary.

Both boards are 1" x 2.175"


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## Mike McLane

If PPCB is involved it should be something they can source through their existing vendors.  Mr. PPCB (if interested) would have to chime in on that, but my guess would be that a thru-hole requiring user assy is more up his alley (fewer issues of warranties, quality control, etc.).  If Sushi were to make it as a finished unit you'd probably want to go the other way.  Since my little circuit board strictly involves connections to off board components I'm guessing a simple eyelet or turret board would be all that's required.  That said, in looking at your finished dimensions (1" x 2.175") I crunched my board down a bit so all of the components fit "shoulder to shoulder" and reduced the board to 1.75" x 2.25" (see attached).  Is there any heating or other issue that would preclude that?  At that point you could append your power supply to the same board for a total of 2.75" x 2.25".  Probably got some room to loosen that up a bit if need be.  I figure it would have to go in a wider box (1590BB?) so that the tube could reside along side the board and have the full depth of the box for breathing room as well.  Any of this make sense?

Thanks again for your help!!!


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## vigilante398

Mike McLane said:


> If PPCB is involved it should be something they can source through their existing vendors.  Mr. PPCB (if interested) would have to chime in on that, but my guess would be that a thru-hole requiring user assy is more up his alley (fewer issues of warranties, quality control, etc.).  If Sushi were to make it as a finished unit you'd probably want to go the other way.  Since my little circuit board strictly involves connections to off board components I'm guessing a simple eyelet or turret board would be all that's required.  That said, in looking at your finished dimensions (1" x 2.175") I crunched my board down a bit so all of the components fit "shoulder to shoulder" and reduced the board to 1.75" x 2.25" (see attached).  Is there any heating or other issue that would preclude that?  At that point you could append your power supply to the same board for a total of 2.75" x 2.25".  Probably got some room to loosen that up a bit if need be.  I figure it would have to go in a wider box (1590BB?) so that the tube could reside along side the board and have the full depth of the box for breathing room as well.  Any of this make sense?
> 
> Thanks again for your help!!!


I already ordered both versions of the boards  Heating shouldn't be an issue, but on the through-hole board I did place the 78L06 on the edge so it could easily be attached to the enclosure to dissipate heat. If you're only heating one tube I don't expect this to be necessary, but if you're trying to run two or more then it may get toasty to the point of thermal shutdown. You won't damage the regulator, but it will shut down and you'll need to wait until it cools back down before you power it on again.

On the SMD version the 6V regulator is only rated for 500mA, which means it's only good for a single tube. As I mentioned in my write-up you can use 9V or 12V directly to the tube heaters without using the 6V regulator, so that's an option for using more than one tube. I tried to get reasonable copper-copper tracing so I'm confident saying you can run this up to 300V, I personally wouldn't take it much farther than that.

As for the size, the main reason I went for the 1" height was so the board can be mounted on the sidewall of something like a 125B. The mounting holes are for M2 diameter mounting hardware, personally I use brass standoffs for things like this. The boards take a couple days for fabrication, then SMD assembly takes an extra day or so, and shipping is 3-7 business days, so I usually get boards in 1-2 weeks. I'll let you know when they show up and I have a chance to test them.


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## Mike McLane

Holy cow!  We're cookin' now!  So you wouldn't go with a single integrated board, but a separate board for power supply for the reasons cited.  You're into the territory of how to stuff things into the box and are bringing up considerations that exceeded my knowledge or experience.  As far as high voltage goes the old Fender schematics indicate 275V if I read it correctly.  Again, all I'm looking for is a basic single channel clean to slight break up BF Fender front end so what you're proposing seems to have some "margin" built into it as I wouldn't want to be running right at the ragged edge of any components ability.  Attached are the values of components I've extracted from reviewing the various schematics and layouts.  Some guys show stouter specs than some of these shown, but it may involve larger component sizes.  I would defer to your judgement if you think they need to be altered.  Also, the caps in my DR clone are Mallory M150, but I would again defer to your judgement as to specific brand/model of components.


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## Mike McLane

Kingsley specs 9vdc/500mA for their power source.  I assume that's more than adequate for what we're looking at for a single channel unit.  I only bring it up inlight of my previous comment on engineering some "margin" into the beast and your comment on the 500mA limit of the 6V voltage regulator.  Wouldn't want that to be a weak link in the chain.  You know better.

Ya know?  The way things are going I might have to learn how to play the guitar


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## vigilante398

Mike McLane said:


> So you wouldn't go with a single integrated board, but a separate board for power supply for the reasons cited.  You're into the territory of how to stuff things into the box and are bringing up considerations that exceeded my knowledge or experience.  As far as high voltage goes the old Fender schematics indicate 275V if I read it correctly.  Again, all I'm looking for is a basic single channel clean to slight break up BF Fender front end so what you're proposing seems to have some "margin" built into it as I wouldn't want to be running right at the ragged edge of any components ability.  Attached are the values of components I've extracted from reviewing the various schematics and layouts.  Some guys show stouter specs than some of these shown, but it may involve larger component sizes.  I would defer to your judgement if you think they need to be altered.  Also, the caps in my DR clone are Mallory M150, but I would again defer to your judgement as to specific brand/model of components.


I would go with a separate power supply board rather than a single integrated board simply for ease of design. I don't want to take the whole DIY experience away from you, I'm just giving you a tool for your project. When I do preamps I do the whole thing on one integrated board as it makes everything neater and makes less room for error. My thoughts on the component choices:

*630V film caps* - I use Mallory 150S for my non-SMD preamps and they're rated for 630V and I have no issues with them. They're fabulous.
*500V silver mica cap* - sounds about right, 500V is one of the more common ratings for silver mica caps
*100V electrolytic caps *- that's excessive. I wouldn't go below 25V, which is what I typically use for electrolytics on cathodes but it doesn't absolutely have to be as high as 100V.
*2W resistors - *absolutely not, completely unnecessary. My through-hole preamps use 1/2W carbon comp and my SMD preamps use 1/8W resistors, there's no reason to go as high as 2W in a preamp. Completely unnecessary and a waste of money.
*1W resistors* - same as above. Unless you're going for a particular look and you have some really cool looking 1W resistors there's no reason not to use 1/4W or 1/2W everywhere.


Mike McLane said:


> Kingsley specs 9vdc/500mA for their power source.  I assume that's more than adequate for what we're looking at for a single channel unit.  I only bring it up inlight of my previous comment on engineering some "margin" into the beast and your comment on the 500mA limit of the 6V voltage regulator.  Wouldn't want that to be a weak link in the chain.  You know better.
> 
> Ya know?  The way things are going I might have to learn how to play the guitar


I would say 9V/500mA is bare minimum. When the tube is warmed up and you're operating you'll be pulling less than that, but when the tube is trying to get up to temperature it will try to pull as much as it can, which can cause the voltage to sag if the power supply can't keep up. But with a 500mA supply you should still be good after a minute or so.

I've heard you can plug guitars into these, but I haven't had time to try it, I just build them for the sake of building them. The 1/4" audio jacks are for aesthetics


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## Mike McLane

What kind of enclosure do you envision?  I was messing around with stuffing the PS & CB in a 1590BB and still finding room for in/out jacks and DC jack up top (like your units) and two foot switches (on/bypass, EQ Lift) down below and I can't find any place to put my tube !!! How's a guy supposed get by if he ain't got no place to stick his tube!?!?!?


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## vigilante398

I only have one tube pedal that uses two footswitches, and I put it in a 1590XX so I don't have to deal with space issues. But if you're set on the 1590BB I would recommend mounting the power supply PCB to the side wall with your signal PCB next to it. You can't completely center the jacks or footswitches as they'll hit the tube, but if you shift things off to the side slightly you should be able to make it work. Obviously exactly what this looks like will depend on what kind of tube socket you have and how you choose to mount it, but this would be my suggestion.


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## Mike McLane

For now let's delete the foot-switchable EQ Lift.  I might leave it in as non-foot-switchable, but all of that appears to not involve the design of either circuit board. If left foot-switchable it begs to have an additional volume pot to balance the EQ Lift volume with the base tone.  Now you're up to 7 pots!  Without a footswitch you can use it to get a more aggressive "tweedy" sound, but that's the tone you get. . . period.  I have this on my current amp and even though it's a great feature I generally just set it straight BF Fender clean to edge-of-break-up and use pedals for whatever additional flavor I'm after.  *After all, that's what PPCB is here for!!*   So it wouldn't bither me a bot to go straight AB763 for now.

BTW, are you doing all of these nifty renderings in Fusion 360??


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## vigilante398

Mike McLane said:


> BTW, are you doing all of these nifty renderings in Fusion 360??


Nope, these are all in Altium Designer. That's what I use for schematics and PCB layouts, but they've always had limited 3D visual capability and the newer versions keep getting better. For components you can keep the 4D model attached to the library component (like in diptrace) for 3D views, but you can also import additional 3D models like enclosures, jacks, etc. to see how things are going to fit. Not the only way to do it, but it's the way I do it.


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## Mike McLane

All my stuff is done in AutoCad, but I'm dipping my toe into Fusion 360 water.  I'm a member of a Maker Lab here and made some other guitar related stuff like a backplate noise suppression coil for my Strat and a chambered Tele body.  Then I started this "pedal gig".  With Fusion 360 I'd like to try my hand at a Strat body.  Anyway. . . . back to amp pedals!!!!!


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## vigilante398

Mike McLane said:


> All my stuff is done in AutoCad, but I'm dipping my toe into Fusion 360 water.  I'm a member of a Maker Lab here and made some other guitar related stuff like a backplate noise suppression coil for my Strat and a chambered Tele body.  Then I started this "pedal gig".  With Fusion 360 I'd like to try my hand at a Strat body.  Anyway. . . . back to amp pedals!!!!!
> 
> View attachment 24327View attachment 24329View attachment 24328View attachment 24330


Oh very cool. I started learning Fusion 360 when I got my first 3D printer, then my work got my a SolidWorks license so I stopped using Fusion  I always wanted to check out a makerspace, but when I started getting into this stuff I lived in a town that didn't have one, I just started buying all my own equipment and now I don't need a makerspace. My wife calls them all my otherwise useless tax deductions


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## Mike McLane

1.  What type of pots do you use?  I would guess standard 12mm would take up quite a bit of depth and hamper placement of the Sig board relative to the PS to some degree.
2.  Any rec's on tube socket brand/type?  How do you physically secure it?  Kingsley appears to just use brass standoffs bolted to the wall of the enclosure.
3.  How do you physically secure the circuit boards.  Particularly given that you want the voltage regulator to be affixed to the enclosure for heat dissipation.  I don't notice any protruding screw heads on the exterior surface of your units that would indicate "bolted in" standoffs so I'm guessing its magic?????


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## vigilante398

Mike McLane said:


> 1.  What type of pots do you use?  I would guess standard 12mm would take up quite a bit of depth and hamper placement of the Sig board relative to the PS to some degree.
> 2.  Any rec's on tube socket brand/type?  How do you physically secure it?  Kingsley appears to just use brass standoffs bolted to the wall of the enclosure.
> 3.  How do you physically secure the circuit boards.  Particularly given that you want the voltage regulator to be affixed to the enclosure for heat dissipation.  I don't notice any protruding screw heads on the exterior surface of your units that would indicate "bolted in" standoffs so I'm guessing its magic?????


Well I have to separate what I usually do from what I'm looking at for your build here, but this is what I do:

I use 9mm PCB mount pots (Alpha or Cusack, I use them interchangeably), those are also what I use to mount the PCB to the enclosure. I like the size and the number I can fit in a small box and also the mechanical tabs for securing it.
I like Belton, but the PCB mount sockets I use on my builds are just no-name ones I get in bulk from a Chinese supplier. For builds like what you're describing I would recommend something like these: https://www.tubesandmore.com/products/socket-belton-9-pin-miniature-top-mount
I can show you how I envisioned the mounting of the power supply board when the boards show up, but my intention was that it mounts against the wall with brass standoffs but snugged all the way to the top of the enclosure so the heatsink of the 6V regulator is flush against the enclosure, then you can just drop a machine screw through the top and bolt the heatsink to the enclosure. That being said I don't use regulators on my builds and I just run the tube heaters in series (instead of parallel) straight off the input at 9-12V.


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## Mike McLane

So you would design the pots into the signal board PCB similar to the way PPCB does?  So as with your PS board, a properly designed PCB could handle the current required for the signal board?  That said I did some toying with how one would route the traces accommodate PCB mounted pots and have attached my humble offering.  Also did a rough layout for a single foot switch 1590BB and I still don't know how you could slide a tube in there. But most important, we have yet to deal with the LED indicator . As long as you feel that a PCB signal board is good-to-go then it seems there's not much more head scratching to do until you get a look at the power supply daughter board (i.e. - I can leave you alone for a week or so). Thx tons for your help on this!


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## Kreisky

Hello... is this a tube preamp like "Space heater" on Sushiboxfx? 

I got a preamp pedal from THCustom, Valvetizer, very nice in the clean version, maybe the limit of that pedal is that if you use the clean-version, even if you turn up Gain pot, it still remains clean (with 12au7...) I will maybe try to mod it with a switch and a cathode capacitor to have some overdrive. Anyway, I've listened to Space heater audio and it's very nice sounding!


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## vigilante398

Kreisky said:


> Hello... is this a tube preamp like "Space heater" on Sushiboxfx?
> 
> I got a preamp pedal from THCustom, Valvetizer, very nice in the clean version, maybe the limit of that pedal is that if you use the clean-version, even if you turn up Gain pot, it still remains clean (with 12au7...) I will maybe try to mod it with a switch and a cathode capacitor to have some overdrive. Anyway, I've listened to Space heater audio and it's very nice sounding!


Hi there, I'm Nathan from Sushi Box FX  The high voltage daughter board I posted pictures of earlier are the same circuit I use in all my tube pedals. If you want to see how Space Heater was designed you can read more on theory here: https://forum.pedalpcb.com/threads/tubes-101-intro-to-tube-preamp-design.10625/

Trying to remember what the voltage is that they get out of that CD40106 circuit in the Valvetizer. 60V, somewhere around there? Anyway. I've never built it myself, but I know people that have built it and liked it.


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## vigilante398

Mike McLane said:


> So you would design the pots into the signal board PCB similar to the way PPCB does?  So as with your PS board, a properly designed PCB could handle the current required for the signal board?  That said I did some toying with how one would route the traces accommodate PCB mounted pots and have attached my humble offering.  Also did a rough layout for a single foot switch 1590BB and I still don't know how you could slide a tube in there. But most important, we have yet to deal with the LED indicator . As long as you feel that a PCB signal board is good-to-go then it seems there's not much more head scratching to do until you get a look at the power supply daughter board (i.e. - I can leave you alone for a week or so). Thx tons for your help on this!


I'll take a look at how to fit pots in there, but 1590BB doesn't have enough vertical clearance for the jacks to go over the PCB, so you can't stretch it very far vertically. I'll see how much guidance I can give without just designing the board for you


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## Mike McLane

A 1590C will give 2.2 height.  That should provide enough height wouldn't it?  I've ordered signal board parts.  Let me do a physical mock up while your waiting on the PD board.


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## vigilante398

Mike McLane said:


> A 1590C will give 2.2 height.  That should provide enough height wouldn't it?  I've ordered signal board parts.  Let me do a physical mock up while your waiting on the PD board.


I threw together a quick design on the signal board to see how small I could get it with board-mounted 16mm pots. I kept the 2.25" width but had to grow the height a little to fit two rows of pots.  I'll plug it into my 3D model and see what it looks like.


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## vigilante398

I know you said you're losing the EQ Shift footswitch, but even with it this looks like it could fit. you have to squeeze pots together a little, but they'll fit.


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## Mike McLane

What would it cost to have your vendor build one of these for testing?


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## vigilante398

Mike McLane said:


> What would it cost to have your vendor build one of these for testing?


I mean bare PCBs are like $5 for 5, shipping is where they get you. I could throw these on with my next order (which will literally be tomorrow because I have a PCB addiction) if you want to try one out. Save a couple bucks on shipping.

Oh and I forgot to mention the footprints were sized for 1/2W carbon comp resistors, Mallory 150 film caps, and 25V electrolytics. That's what I use so that's what I had in my library


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## Mike McLane

When you say "bare" do you mean the design you showed above except absent the electrical components?  I ordered 1/2W resistors and 50V electrolytics, but that shouldn't be a big issue.  Just tell me what the number is.  I should be around first thing in the morning so I can respond quickly.


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## Feral Feline

Re pot sizes... I thought the standard size of pots was 16mm. I use 16mm and 9mm, the only thing I've ever seen with 12mm is BYOC stuff.
I've never seen them in my Internet travels or I would've picked some up, but I've not sought them out specifically so maybe they're more available than I think. It's a good size, not sure why there seems to be a dearth of 12mm.

PS: increase your space for jacks, from 
1590BB (34mm) vertIcal space to 
1590BB2 (38mm) and even more vertical, the 
1590BBS.(42mm)


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## Kreisky

vigilante398 said:


> Hi there, I'm Nathan from Sushi Box FX  The high voltage daughter board I posted pictures of earlier are the same circuit I use in all my tube pedals. If you want to see how Space Heater was designed you can read more on theory here: https://forum.pedalpcb.com/threads/tubes-101-intro-to-tube-preamp-design.10625/
> 
> Trying to remember what the voltage is that they get out of that CD40106 circuit in the Valvetizer. 60V, somewhere around there? Anyway. I've never built it myself, but I know people that have built it and liked it.


Hi Nathan, thanks for the link to your tube preamp design! That's different from Valvetizer, as you say it works about at 60-70V with 9-12vdc input. On my version it's a cathode foller, that's why there's no overdrive at all.
Anyway your Space Heather is very nice but to high voltage to try from scratch myself!


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## vigilante398

I can give a quick update to this for anyone that's interested. I got the boards in a few weeks ago and have tested the SMD high voltage boards, they work great. I don't regularly stock a lot of through-hole parts but I ordered parts to put together a through-hole high voltage board for verification. Once those are verified I'll solder up one of the preamp boards and see how that sounds, though we've already determined there are some changes to be made to it for ease of building so there will likely be another revision.


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## vigilante398

Got my Tayda order in yesterday and verified the through-hole version of the power supply. The output pads are spaced on a 100mil grid so you can add header pins and throw it on a breadboard if you want. 
Now just need to verify the preamp board.


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## Feral Feline

@vigilante398 
Are you going to be offering these PCBs through Sushibox, Nathan?


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## vigilante398

Feral Feline said:


> @vigilante398
> Are you going to be offering these PCBs through Sushibox, Nathan?


I'm thinking about it. I plan to make at least a small number available in some form, whether formally or informally. Not trying to jump into selling PCBs regularly, but enough people have expressed interest I figured I would at least do a little.


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## daeg

Mike McLane said:


> I wonder about a tube driven preamp as a front end to a modeler setup to impart some "tubiness".


This is what the Vox VT series amps are. IIRC it goes:

Single Tube Preamp -> Digital MultiFX 1 (Noise Gate, Tuner, Compressor, RangeMaster, Tubescreamer, OD3, etc) -> Digital EQ / Amp Modeler ->  Digital MultiFX 2 (Harmonic Tremolo, Chorus, Delay, etc) -> Digital MultiFX 3 (Reverb) -> Class D Power Amp -> Neutral-ish Speaker

The Tube definitely adds some warmth and the modeled sounds are about 2/3ds of the way there, but overall it isn't a joy to play like the any of the real amps it tires to model. That said I keep mine as a backup since it's small, lightweight, reliable and loud.


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## daeg

Mike McLane said:


> The whole Ukraine thing has brought up the tube sourcing saga and suggests the eventual death of tube amps as the predominant force in the guitardom.


Some companies out there have tried making solid-state, drop-in replacements for tubes. Has anyone tried any of them out? 

I have yet to go down that rabbit-hole, but it would be a dream to be able to replace a 12AX7 or EL84 with something that is more consistent, not NOS and is going to have 10x the lifespan.


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## vigilante398

daeg said:


> Some companies out there have tried making solid-state, drop-in replacements for tubes. Has anyone tried any of them out?
> 
> I have yet to go down that rabbit-hole, but it would be a dream to be able to replace a 12AX7 or EL84 with something that is more consistent, not NOS and is going to have 10x the lifespan.


I have a couple of the AMT Warm Stones which are 12AX7 replacements. As a tube fanatic I was skeptical, but I have to admit they did an excellent job and it's damn hard to hear a difference when I A/B them against real tubes.

That being said AMT is in Russia so difficult to buy now, and a single Warm Stone is right around $50.


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## daeg

vigilante398 said:


> I have a couple of the AMT Warm Stones which are 12AX7 replacements. As a tube fanatic I was skeptical, but I have to admit they did an excellent job and it's damn hard to hear a difference when I A/B them against real tubes.
> 
> That being said AMT is in Russia so difficult to buy now, and a single Warm Stone is right around $50.


After I posted I went through a few forums and the consensus is that no one would be able to tell the difference in a blind test.

I might try one out. No one is doing this with Power Tubes or Rectifier Tubes right? It seems like it's just AMT and their 12AX7 preamp tube.


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## vigilante398

daeg said:


> After I posted I went through a few forums and the consensus is that no one would be able to tell the difference in a blind test.
> 
> I might try one out. No one is doing this with Power Tubes or Rectifier Tubes right? It seems like it's just AMT and their 12AX7 preamp tube.


Yeah a drop-in replacement for a power tube is going to be incredibly difficult, I don't think anyone has done it. You would need to have a class-A amplifier that could be coupled into class-AB that can successfully produce the same power levels of tubes at the same impedances as tubes in order to play nicely with your output transformer. Output transformers really ruin everything. Solid-state amps don't need them as it's possible to have much lower output impedances than tubes just due to manufacturing, so forcing a solid state device through an output transformer is just a messy thing to ask.

I'm already pretty impressed at the Warm Stone, but I would be beyond impressed if someone could design a drop-in power tube replacement.

Oh it has been done with rectifier tubes though, there are a few companies that do it. I have a Weber "copper cap" rectifier that's a drop-in for a tube rectifier, and CE Distribution (the wholesale arm of Amplifiedparts/Antique Electronic Supply) makes one as well.


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## daeg

vigilante398 said:


> Yeah a drop-in replacement for a power tube is going to be incredibly difficult, I don't think anyone has done it. You would need to have a class-A amplifier that could be coupled into class-AB that can successfully produce the same power levels of tubes at the same impedances as tubes in order to play nicely with your output transformer. Output transformers really ruin everything. Solid-state amps don't need them as it's possible to have much lower output impedances than tubes just due to manufacturing, so forcing a solid state device through an output transformer is just a messy thing to ask.
> 
> I'm already pretty impressed at the Warm Stone, but I would be beyond impressed if someone could design a drop-in power tube replacement.
> 
> Oh it has been done with rectifier tubes though, there are a few companies that do it. I have a Weber "copper cap" rectifier that's a drop-in for a tube rectifier, and CE Distribution (the wholesale arm of Amplifiedparts/Antique Electronic Supply) makes one as well.


Great info. Ty.


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