# Design Challenge #2



## Chuck D. Bones (Feb 28, 2021)

Boss has built millions of pedals using the CD4007 as a flip-flop in the engage-bypass switching.  The challenge here is to build a pedal using a CD4007 IC in the audio path.
Hint: Catalinbread has already done it, so take a look at their discontinued pedals for clues.

Here's my 2nd version.  1st version had too much gain (yeah, like that's even possible).  4 knobs (L-R): Bass, Volume, Treble, Gain.  Remarkably quiet for a CMOS-based circuit.  No NOS parts here either.  Still tweaking, but it's close.  It's not a copy of a Catalinbread pedal.


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## fig (Mar 1, 2021)

Hyper-Pak?


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## Chuck D. Bones (Mar 1, 2021)

That's one of Catalinbread's discontinued CD4007-based pedals.


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## Chuck D. Bones (Mar 1, 2021)

The three I know of are the Hyperpak, the V8 Fuzz Engine (a higher-gain version of the Hyperpak) and the Supercharged Overdrive (SCOD for short).

Here's what I have so far:



This thing is crazy loud and has a shit-ton of sustain.  Unity VOLUME is around 9:00. Even with GAIN at zero there is plenty of dirt. Crank the GAIN for some sweet feedback, even at bedroom volume. Very quiet even with GAIN dimed.  The JFET preamp is similar to the 1st stage in the Fuchsia.  The GAIN control is similar to the MI Audio Crunch Box and Marshall Blues Breaker.  We don't say "plagiarize," we say "research."  The BASS control ranges from _tight _to _roar_.  TREBLE goes from _dark _to _sizzle_. I didn't spend too much time fiddling component values. The DMM in the top pic is reading the voltage on the CD4007's power rail. Total current draw is under 2mA.

For the next iteration, I'm moving the GAIN control to the 2nd & 3rd stages and the TREBLE control between the 3rd and 4th stages.


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## cooder (Mar 1, 2021)

Looking dazzling again... !


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## Chuck D. Bones (Mar 2, 2021)

I think there are many possibilities for using the CD4007's three CMOS gain stages.  Definitely has potential for amplifier emulation.


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## Dreamlands (Mar 2, 2021)

Came across this:   


			https://www.experimentalistsanonymous.com/diy/Schematics/Filters%20Wahs%20and%20VCFs/4007%20Based%20VCF.pdf


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## zgrav (Mar 2, 2021)

Nice to see these possibilities compared to the fuzz circuits using the 4049 chips.


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## Chuck D. Bones (Mar 2, 2021)

Dreamlands said:


> Came across this:
> 
> 
> https://www.experimentalistsanonymous.com/diy/Schematics/Filters%20Wahs%20and%20VCFs/4007%20Based%20VCF.pdf


Interesting!


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## zgrav (Mar 5, 2021)

that is good to read that  you are not getting a lot of noise from the 4007.  and no buffer for the output seems to make sense, even though I've read that some of the catalinbread circuits used buffers on each side of that chip.


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## Chuck D. Bones (Mar 8, 2021)

Still messing with this one.  I'm on the 6th or 7th revision.  Tried a bunch of stuff that didn't sound good: building a Tweed Sound, Box o' Rocks or a WIIO using the 4007 in place of the FETs.  Tried the ThunderZone tone control arrangement.  Rev 1.3 above sounded the best so far.  The latest rev is pretty close to rev 1.3, but has a variable mid boost on the 2nd stage using a gyrator.  There are some component value changes as well.


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## Chuck D. Bones (Mar 8, 2021)

zgrav said:


> Nice to see these possibilities compared to the fuzz circuits using the 4049 chips.


The two ICs are pretty similar.  For me, the advantages of the CD4007 are
1) I can install current-limiting resistors between the upper and lower FETs on 2 of the 3 stages.
2) I can use just the upper or lower FET on some of the stages.
3) I'm not tempted to use all 6 inverters in the 4049.  The simplicity of the 4007 enforces a bit more discipline.


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## peccary (Mar 8, 2021)

Are there many CMOS overdrives out there? Are CMOS chips good for other kinds of effects? I have a few different types of CMOS ICs in my collection that I'm planning on playing around with on some Beavis projects (I'm interested in DIY synth stuff) and I had been wondering if they could have other uses as well.

Also, are these projects you work on here going to be available once you get them to a place you like?


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## Chuck D. Bones (Mar 8, 2021)

There are a few.  Runoffgroove has a dual distortion called Double-D based on the 4049.  I built a modd'ed version.  The problem with using CMOS in an analog application is there are no guarantees how they will perform.  The 4049's made these days are pretty noisy.  I have a handful of NOS 4049s from Fairchild and RCA that are quiet. Fortunately, the TI 4007's I procured recently are quiet.  TI could change the recipe any time and then they might not be so quiet.

4013 flip-flops get used as frequency dividers in octave-down pedals.  You can certainly build synth modules using CMOS to make freq dividers, freq multipliers, sequencers, oscillators, etc.  Some CMOS parts, like the 4046, contain a VCO, so it's actually part digital, part analog.

I breadboarded a version of the Maestro FSH-1 and I used a digital pseudo-random sequence generator made from CMOS gates & shift registers in place of the noisy transistor / sample & hold circuit.  A pesudo-random generator appears truly random until the pattern (eventually) repeats.  The one I built is 33-bits long and will run for about 27 years at full-speed before it repeats. 

Now and then, I come up with something that someone, PedalPCB or one of the guys on the forums, finds good enough to merit a board layout.
One of these days I'll take the time to learn DipTrace.


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## Chuck D. Bones (Mar 10, 2021)

Stick a fork in it, it's done.





I liked having the MID control, but I wanted it to go boost or cut.  Now it does.  All of the controls are usable across their entire range.  Not too many dirt pedals can claim that.  There is no clean setting unless you back the guitar volume down. Other JFETs will work, just tweak R3 to get Q1's drain around 5V.  The MID control is tuned to about 600Hz.  The MID freq can be tweaked by changing C5 or C6.  Increasing C5 lowers the freq and makes the mid hump broader and the dip deeper.  Increasing C6 lowers the freq and makes the mid hump narrower and the dip shallower.  Decreasing the caps has the opposite effect.  If you don't want the MID control, then build v1.3. As usual, all component values are negotiable.  The TREBLE control is tuned to a "Goldilocks" range of not too dark, not too bright.  R13 and R17 are pretty well optimized for the most headroom.  This thing gets quite loud.  Total current draw is just over 3mA.


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## jubal81 (Mar 10, 2021)

Damn, looks hot! 
In my experience, CMOS distortions sounds best when they're wound-up a bit anyway, so I like that you didn't feel compelled to make it be able to clean up.


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## cooder (Mar 10, 2021)

That's some hot stuff again, Chuck! You're the man...!


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## Chuck D. Bones (Mar 10, 2021)

jubal81 said:


> Damn, looks hot!
> In my experience, CMOS distortions sounds best when they're wound-up a bit anyway, so I like that you didn't feel compelled to make it be able to clean up.


Yeah, they don't all have be "edge of breakup."


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## MattG (May 6, 2021)

Hi Chuck, a couple questions about Q1, the PF5102:

Will other JFETs work here?  In particular, a 2n5457, since I already have some of those on hand?
I read your post on JFETs.  Previously I've always used JFETs in a paint-by-numbers manner (not knowing any better).  For Q1, does the JFET need to be tested for some particular parameters?

I whipped up a PCB for the circuit in post #15 above, waiting on delivery.  Now working on the BOM.

Thanks!


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## Chuck D. Bones (May 6, 2021)

Other JFETs will work.  My PF5102s have Vp around -1.2V.  The Vp spec range for 2N5457 is -0.5V to -6.0V.  If yours land near -1.2V, you can use them with no circuit mods.  Otherwise, you can adjust R4 to accommodate different Vp within the range -0.5V to -2.0V.  Use this formula and round up to the closest common value (use a positive number for Vp in this calc).

R4 = 4.7K * Vp / 1.2.  

Example: if you measure 2.0V for Vp, then use 8.2K for R4.


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## Chuck D. Bones (Jun 9, 2021)

Some kind soul made some prototype boards, so I built one up.  I ended up changing 4 resistors to brighten up the first stage a little bit.

Top row: BASS, MID, TREBLE
Bottom row: LEVEL, GAIN



 

Hadn't installed the LED when I took this pic and I'm fresh out of power jacks.


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## MattG (Jun 29, 2021)

Hi all,

I made the prototype PCBs for this overdrive, and with Chuck's help, fixed some silly issues.  I now have a stack of revised PCBs.  I'm happy to give these away for no cost, while supplies last.  PM me with your mailing address, and I'll drop one in an envelope and mail it to you (USA addresses only).  I'll say one per person for now, until they run out or demand appears to have waned.  Give me some time to get them shipped, as I'd prefer to do them in a few batches to save time.  If you want a more robust shipping option, I can do the USPS small flat rate priority mail box if you PayPal me $8 to cover the mailing cost.

I'm also attaching to this post several files:

A ZIP file containing the BOM in multiple formats
The Gerber files I used for fabrication.  I used JLCPCB, so if you want to have your own fabricated, you can use this zip file directly with JLCPCB.  These Gerbers "might" work with other fab houses.
The circuit schematic
A PDF with the layout of the pots - you can print this and use it as an enclosure drill guide (at least for the knobs)
A ZIP file containing the Mouser Project with most of the parts (in multiple formats) (note: this was an edit after the initial post)

I can post the KiCad files if requested.

Here are some pics of the bare boards, and my completed build.


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## Chuck D. Bones (Jun 29, 2021)

This is the kind of post that deserves the🍆 emoji.


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## Sturdag Lagernathy (Jul 5, 2021)

So what do you call it, Chuck?


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## Chuck D. Bones (Jul 5, 2021)

So far, I've been calling it *CMOS Overdrive*, which is both accurate and boring. So if anyone has a better name, I'm open to suggestions.


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## zgrav (Jul 5, 2021)

CMOverdrve
CeeMO Head Room


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## Barry (Jul 5, 2021)

Chuck D. Bones said:


> Some kind soul made some prototype boards, so I built one up.  I ended up changing 4 resistors to brighten up the first stage a little bit.
> 
> Top row: BASS, MID, TREBLE
> Bottom row: LEVEL, GAIN
> ...


What were the resistor changes you made?


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## Chuck D. Bones (Jul 5, 2021)

R1 -> 4.7K
R3 -> 15K
R4 -> 3.3K
R14 -> 100K
C2 -> 470nF

Lowers Q1's gain a little and improves the top end.  It's not a huge improvement, but I like it better.  Lowering R14 recovers the lost gain.


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## Barry (Jul 5, 2021)

Chuck D. Bones said:


> R1 -> 4.7K
> R3 -> 15K
> R4 -> 3.3K
> R14 -> 100K
> ...


Thanks


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## Chuck D. Bones (Jul 5, 2021)

So you're building one of these, hmmmm?


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## Barry (Jul 5, 2021)

Chuck D. Bones said:


> So you're building one of these, hmmmm?


Actually I think he's sending two


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## music6000 (Jul 5, 2021)

I would build it but I'm down under in Australia!


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## Chuck D. Bones (Jul 5, 2021)

You could roll an eyelet board!


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## music6000 (Jul 5, 2021)

Chuck D. Bones said:


> You could roll an eyelet board!


Yes, but then it would be my version & I want an official C.D.B PCB    !!!

I have already done the Hyper Pak with Tone control in Eyelet Board


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## Chuck D. Bones (Jul 5, 2021)

An IC seems out of place on an eyelet board, but you made it work!  Looks great inside & out, as always.


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## MattG (Jul 6, 2021)

music6000 said:


> I would build it but I'm down under in Australia!



I hate to exclude folks outside the USA, but international shipping is really expensive (and kind of a hassle).  Just as an example, the USPS small flat rate priority mail boxes cost just over $8 to ship domestically.  I've shipped a few of those to Europe, and it's over $50!

For those of you outside of USA who are interested in the boards, it's probably worth checking out JLCPCB - you can upload the Gerber files (the single .zip file I posted above) and get a quote.  IIRC, it's only $2 for five or 10 boards, and the least-cost shipping option to the USA is generally under $10.  I suspect the total cost would be similar to what it would cost for me to ship a single board.  And if you can find a buddy in your part of the world, you can split the cost!


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## Sturdag Lagernathy (Jul 7, 2021)

I got a board coming my way to, hopefully. In honor of Chuck, Imma call mine "The Bone Driver"...  or maybe "The Bone Screamer"..."The Tone Bone"? Well, I'm sure I'll know after I hear it!


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## Barry (Jul 7, 2021)

Sturdag Lagernathy said:


> I got a board coming my way to, hopefully. In honor of Chuck, Imma call mine "The Bone Driver"...  or maybe "The Bone Screamer"..."The Tone Bone"? Well, I'm sure I'll know after I hear it!


Boner Overdrive


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## MattG (Jul 8, 2021)

Barry said:


> Boner Overdrive


Or how about just "Boner-drive"


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## Barry (Jul 8, 2021)

MattG said:


> Or how about just "Boner-drive"


Or Driving.....eh, I better leave well enough alone


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## Chuck D. Bones (Jul 9, 2021)

There are so many sleazy pedals names out there, I think the good ones are already taken.








Not to mention the offerings from Metasonix.


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## Sturdag Lagernathy (Jul 9, 2021)

Ooh man! Let's hope we see the "Bag of Dicks" in the shop soon!


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## Barry (Jul 9, 2021)

Sturdag Lagernathy said:


> Ooh man! Let's hope we see the "Bag of Dicks" in the shop soon!





Chuck D. Bones said:


> There are so many sleazy pedals names out there, I think the good ones are already taken.
> 
> View attachment 13447View attachment 13448View attachment 13449
> Not to mention the offerings from Metasonix.


Let's not forget the "Super Hard On"


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## MattG (Jul 10, 2021)

I just finished build #2.  I used the alternate values (shown on the schematic and I think also earlier in this thread).  I definitely prefer the alternate values with my humbucker guitar.  I couldn't make up my mind with my single coil guitar, maybe a slight preference towards the stock values.  The differences between stock and alternate values aren't night and day; they are subtle but noticeable.  To my ears, there is more treble/high end at lower gain with the alternate values.  (Although, both guitars are long overdue for a string change, so maybe I'm overcompensating a bit on the highs due to the strings.)

I haven't yet done a side-by-side comparison of the CMOS Overdrive to anything other than the Madbean Mysterioso, which is an almost-clone of the Blackstone Appliance Mosfet Overdrive (BAMO).  I haven't been hunting for any particular sound, but I do like trying out different dirt pedals (my wife might say obsessively so).  Of all the dirt pedals I've built and tried, I kept coming back to the boring old Boss OD-3... that is, until I tried the Mysterioso.  I immediately thought to myself, _this_ is the tone I've always wanted but didn't know I wanted. A normal person would be content to stop once they found "the" sound, but are we not all obsessives in this hobby?  I think the Mysterioso was the first dirt pedal I used that wasn't based on some diode clipping scheme. So I went searching for more CMOS-based designs. I found the RunOffGroove Double-D (also cd4049 based, like the Mysterioso/BAMO), and Chuck's tweaked version.  That led me to this cd4007 project.  (I actually have a prototype CDB-mod Double-D PCB, needs just a little refinement.)

So with all that as a preamble: to my ears, Chuck's CMOS OD certainly has some "family resemblance" to the Mysterioso, but it's definitely its own thing.  I really like the sound of these meant-for-digital-applications CMOS logic chips being used in analog mode and overdriven.  I've seen a lot of people describe the sound as "tube like"; I can't say if that's true, since I've had so few opportunities to really get a tube amp's power section to break up.  Whatever it's called, it's a sound I personally find pleasing.

Chuck's CMOS OD has a great EQ.  It's not terribly common to have a mid control on an overdrive pedal, and the few I've tried never seemed to make a big difference.  But the mid control on the CMOS OD is _really_ effective.  Likewise, so are the bass and treble controls.  So my prediction is, if you build this pedal and like the overall character of the overdrive sound, then I'd be surprised if you couldn't make it work with the rest of your gear because the EQ gives a lot of flexibility.  I'd also suggest either building two like I did, or socketing those components that have alternate values listed. 

All this is based on strictly playing at home.  My band was on hiatus during covid.  We all got vaccines, had one rehearsal, now everyone is busy with summer life, so I haven't had an opportunity to try the CMOS OD in a band mix.  I do have high expectations for it in a band context, though, largely because of the excellent EQ.

Hopefully all the PCBs I sent out have arrived or arrive in the next couple days.  I'm eager to see everyone's build and hear their thoughts!

Slightly amusing side note: when I had #2 nearly finished, I did a power-on sanity test.  I thought it sounded kinda dull, but it was working so I thought I'd finish assembly and then do a longer play-test with it.  Sure enough, once I had everything pretty much done, and all my tools and soldering iron put away, I was admiring my work, when I noticed I had forgot to populate C12!  Argh, something that would take two seconds to do before it was all put together, now I have to tear it down, get my tools back out, etc.  So 20 minutes later, I was actually able to play it without the dull sound!


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## Chuck D. Bones (Jul 10, 2021)

Nice job!  Great write-up. 

The MID control is certainly tunable.  By changing C5, C6 and/or R9 we can have different Q and center freq.  I set it for a fairly low-Q (wasn't going for the stuck wah tone) and 600Hz.


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## Barry (Jul 10, 2021)

Excellant, got my boards today, Thanks Matt!


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## fig (Jul 11, 2021)

Sausage-Fester?


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## Sturdag Lagernathy (Jul 12, 2021)

Uncle Chuck's Tone of Bone!


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## Barry (Jul 13, 2021)

Sturdag Lagernathy said:


> Uncle Chuck's Tone of Bone!


Uncle Chuck's Tone Boner


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## Chuck D. Bones (Jul 14, 2021)

I detect a theme here.


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## JamieJ (Jul 14, 2021)

Where’s @jjjimi84 with the dick references. His horse build comes to mind.


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## jubal81 (Jul 14, 2021)

Changing gears:
Chuck Roast

That's the plan for mine after gaining it up a bit. Sounds awesome, but found myself wishing there was more on the gain knob. Been meaning to do some experiments to boost the distortion when I have some time.


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## jjjimi84 (Jul 14, 2021)

I somehow missed this thread and board but an old friend of mind used to call it his purple headed yogurt slinger. I am sure if given enough time I could paint that monster. 

@Chuck D. Bones your knowledge of circuits astounds me! I absolutely love your threads and read them while scratching my head and hoping something sticks.


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## Bricksnbeatles (Jul 14, 2021)

jjjimi84 said:


> I somehow missed this thread and board but an old friend of mind used to call it his purple headed yogurt slinger. I am sure if given enough time I could paint that monster.


JESUS CHRIST BRO! That’s some disturbing shit 😂


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## Chuck D. Bones (Jul 14, 2021)

jubal81 said:


> Changing gears:
> Chuck Roast
> 
> That's the plan for mine after gaining it up a bit. Sounds awesome, but found myself wishing there was more on the gain knob. Been meaning to do some experiments to boost the distortion when I have some time.


I had two goals with the CMOS Overdrive Deluxe.

1. No JFETs
2. More gain
3. Even better midrange control

OK, three goals.

The first thing you need to know about these CMOS gain stages is the most you can get out of each gain stage is about 40dB.  You can go just so far by increasing the feedback resistor.

The output impedance is a few KΩ, so you have to be careful about loading them.

Lowering Vdd increases gain.  There is a sweet spot around 4V.

In the CMOS OD, I deliberately set the gain of the first stage low to accommodate the MID boost/cut circuit.  In the Deluxe, I used an opamp for the MID boost/cut which left all three CMOS stage available for making large gain.

I tried putting diode hard clippers on the output of one or two of the gain stages.  There was more compression, but the tone was not what I was after.


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## Barry (Jul 14, 2021)

jjjimi84 said:


> I somehow missed this thread and board but an old friend of mind used to call it his purple headed yogurt slinger. I am sure if given enough time I could paint that monster.
> 
> @Chuck D. Bones your knowledge of circuits astounds me! I absolutely love your threads and read them while scratching my head and hoping something sticks.


Not sure I'd want to see it


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## Chuck D. Bones (Jul 14, 2021)

jjjimi84 said:


> I somehow missed this thread and board but an old friend of mind used to call it his purple headed yogurt slinger. I am sure if given enough time I could paint that monster.
> 
> @Chuck D. Bones your knowledge of circuits astounds me! I absolutely love your threads and read them while scratching my head and hoping something sticks.


Scratching something, that's for sure.


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## MattG (Jul 27, 2021)

Anyone built there CDB cd4007 overdrive yet?

I still have several boards available, don't be shy about asking!  (Also: I think I'm going to make a revision that additionally has space for a surface mount Q1, allowing you to use either a through-hole or SMD transistor.  If you're not afraid of SMD soldering, the SMD J201 seems to be readily available.)

Looks like I have band rehearsal on Thursday, so hopefully I'll soon have a report on using it in a live mix.


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## Barry (Jul 27, 2021)

MattG said:


> Anyone built there CDB cd4007 overdrive yet?
> 
> I still have several boards available, don't be shy about asking!  (Also: I think I'm going to make a revision that additionally has space for a surface mount Q1, allowing you to use either a through-hole or SMD transistor.  If you're not afraid of SMD soldering, the SMD J201 seems to be readily available.)
> 
> Looks like I have band rehearsal on Thursday, so hopefully I'll soon have a report on using it in a live mix.


Haven't built mine yet, but they're in the queue and parts have been ordered


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## Chuck D. Bones (Jul 27, 2021)

I loaned mine to a friend and he loved it.  

I'd recommend lower gain JFETs for Q1, such as J201.  The PF5102 kinda muffles the high-end s bit.  The 2SK193 is a very good one because it has extremely low capacitance.  The 2N5457s that are available are at the low end of their gain range, so they should work well too.


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## zgrav (Jul 27, 2021)

MattG said:


> Anyone built there CDB cd4007 overdrive yet?
> 
> I still have several boards available, don't be shy about asking!  (Also: I think I'm going to make a revision that additionally has space for a surface mount Q1, allowing you to use either a through-hole or SMD transistor.  If you're not afraid of SMD soldering, the SMD J201 seems to be readily available.)
> 
> Looks like I have band rehearsal on Thursday, so hopefully I'll soon have a report on using it in a live mix.


Hey Matt G -  if you can send me a board I'd like to give this a try as well.  I'lll send you a message.


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## zgrav (Aug 8, 2021)

MattG was kind enough to send me a couple of the PCBs and I put one together this week using the suggested alternate values.  Easily blows away any of the 4049 fuzz boxes I have built in the past.  Very smooth the the three tone controls are very responsive.  Haven't had much time to experiment with the tone controls because I try out a setting and leave it there for a while. 

Here are a couple of build pics.  Since I had a nice Bismuth color box I called it the PeptOverdrive.


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## Barry (Aug 8, 2021)

Love it!


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## Chuck D. Bones (Aug 9, 2021)

Great design, great board, great build!    

The tone controls are different from the standard Fender/Marshall tone stack.  First and foremost, the tone controls do not interact like they do in the Fender/Marshall tone stack. The BASS control works like the Bass control on the Timmy or the Tight control on a Thermionic.  The MID is an active cut/boost.  The TREBLE control is a bass/treble balance control much like a BMP Tone control or the Fender/Marshall Treble control.

Did you have an issue dialing in the JFET bias?  What is the drain voltage?


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## temol (Aug 9, 2021)

Four pages, couple builds, and no single sound sample? Come on...


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## Sturdag Lagernathy (Aug 9, 2021)

Great build! I've got a few projects to finish ahead of this, but I can hardly wait!

I was looking through some old breadboards the other day, and one had 3 4007's on it! I think it's a sign!


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## zgrav (Aug 9, 2021)

Chuck D. Bones said:


> Great design, great board, great build!
> 
> The tone controls are different from the standard Fender/Marshall tone stack.  First and foremost, the tone controls do not interact like they do in the Fender/Marshall tone stack. The BASS control works like the Bass control on the Timmy or the Tight control on a Thermionic.  The MID is an active cut/boost.  The TREBLE control is a bass/treble balance control much like a BMP Tone control or the Fender/Marshall Treble control.
> 
> Did you have an issue dialing in the JFET bias?  What is the drain voltage?


Drain voltage is 4.33    I liked the sound as is and did not change anything from the alternate values in the build.


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## Chuck D. Bones (Aug 9, 2021)

That voltage is definitely in the ballpark and it passed the listening test, so ROCK ON!


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## MattG (Aug 11, 2021)

zgrav said:


> MattG was kind enough to send me a couple of the PCBs and I put one together this week using the suggested alternate values. Easily blows away any of the 4049 fuzz boxes I have built in the past. Very smooth the the three tone controls are very responsive. Haven't had much time to experiment with the tone controls because I try out a setting and leave it there for a while.
> 
> Here are a couple of build pics. Since I had a nice Bismuth color box I called it the PeptOverdrive.



Looks great, thank you for posting!  I like the name, too - definitely more family friendly than some of the earlier suggested names!  

One small thing I noticed though - on your enclosure, the bass and treble labels are swapped (treble should be on the left, bass on the right).  I know that's probably an atypical ordering of tone controls.  I was trying to keep the PCB traces as short as possible, and I think I saved a few mm of traces by doing it that way.

I still have a few boards left if anyone else wants to join in on the fun.

I've now used this pedal in a band setting a few times - so far so good!  Though to be fair, I'm using it as my "medium-high" gain pedal (drive knob set around 1:00), and not currently doing a lot of songs that call for that.  But I certainly don't plan on removing it any time soon.

Chuck, are there other transistors that would work for Q2, the 2n5089?  I'm flirting with the idea of doing an all-SMD version, and at least Mouser doesn't have an SMD 2n5089.  The PCB fab house I use (JLCPCB) also offers SMD assembly, so I'm thinking maybe this would be a good trial run for that service.  I could design the board to work with e.g. Tayda's pre-drilled enclosures, and radically cut down build time.


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## Chuck D. Bones (Aug 11, 2021)

Any low-noise NPN with HFE > 200 should be fine.  A JFET would also work, but we'd have to adjust the resistor values.  I just noticed on the schematic there are two Q1's.  The BJT should be named Q2.


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## Chuck D. Bones (Aug 11, 2021)

Finally got around to the front panel graphics, such as they are...





I'm still working on improving the process.


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## MattG (Aug 11, 2021)

Chuck D. Bones said:


> Any low-noise NPN with HFE > 200 should be fine. A JFET would also work, but we'd have to adjust the resistor values. I just noticed on the schematic there are two Q1's. The BJT should be named Q2.



Awesome, thanks!



Chuck D. Bones said:


> Finally got around to the front panel graphics, such as they are...



Note that Chuck's build is with the *v1* PCB, so his bass-mid-treble labels are correct.  The v1 PCB was the prototype (also has some of the pots wired backwards).  My two builds I posted in this thread, and all the PCBs I sent out, are *v1.2*, and the position of the treble and bass pots was swapped from v1.



Chuck D. Bones said:


> I'm still working on improving the process.



I think it looks really good!  I assume that's some kind of stamping process?  The (commercial) Fairfield pedals have a similar aesthetic.  Certainly looks better than what I did with the label maker!


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## Chuck D. Bones (Aug 11, 2021)

Thanks, Matt.
Yup, hand-stamped with steel stamps, engineer's mallet and a home-brew anvil.  About 1/2 way thru the top row I improved the anvil and clamped the box in place so it didn't jump around between whacks.  This one was good enough, next one will be better.

As Matt said, this was a v1 board, had to work around some minor issues that were all fixed in v1.2.


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## MattG (Sep 11, 2021)

Bump... anyone else built theirs yet?  @zgrav - any thoughts on the one you built?

Also, I still have a few boards left if anyone else wants them!

I've used mine in several practices now, one backyard party, across several different amps.  I'm still enjoying it!


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## Chuck D. Bones (Sep 11, 2021)

Good to hear!

I know Cooder has built the 7-knob version.


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## zgrav (Sep 13, 2021)

MattG said:


> Bump... anyone else built theirs yet?  @zgrav - any thoughts on the one you built?
> 
> Also, I still have a few boards left if anyone else wants them!
> 
> I've used mine in several practices now, one backyard party, across several different amps.  I'm still enjoying it!


I have left my "PeptOverdrive" on my board and usually leave it on at a relatively low gain setting to fatten the signal.  It has tons more character than any 4049 IC fuzz I have made over the years.


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## Sturdag Lagernathy (Sep 13, 2021)

Built mine! Only played with it for an hour or so, so I'll have more to say soon. First impressions are great! Definitely a great drive. I'd say more British than American sounding? Great range on all controls. Lots crunch if you want it. I used the modified  components.


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## MattG (Sep 14, 2021)

I finally got to play this overdrive through my own amp at volume this past weekend... Thus far I've been using my amp at "family friendly" volumes, or various other random amps at rehearsals.  I like how it sounds across all amps, but my own amp cranked up a bit - I feel that's the best sound yet.  My main amp is a Trinity Triwatt, which is essentially a Hiwatt DR103/DR504 preamp with a more modest 2x6v6 (22ish watts) power section (I built it from the kit, in a 1x12 combo, using the Reeves Vintage Purple speaker).  Of course it could just be "baby bias" - I fully admit to having a preference for the stuff I built myself.  But whatever the reason, it sounded great to me!

@Chuck D. Bones - when you were designing this, did you happen to generate a frequency response graph via simulation, perhaps a few with the tone knobs at various locations?  I'm kind of curious how my aural perception meshes with the actual sonics.


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## Chuck D. Bones (Sep 14, 2021)

Bass control sweep.  Mid at noon.  This is observed at the output of the 2nd stage, going into the distortion stage.




Mid control sweep.  Bass at noon.  This is observed at the output of the 2nd stage, going into the distortion stage.




Treble control sweep.  This is the freq response of the treble control only.  In other words, it's the difference between the distortion stage output and the pedal output.





Gain control sweep.  The Gain control affects the freq response a bit.  This is the end-to-end freq response with Bass, Mid and Treble all at noon.




The max gain is 56dB, making this is a low-to-medium gain pedal.  It can push an amp pretty well, increasing the overall distortion and compression.

If you want more gain, then you need to build the CMOS Distortion Deluxe, AKA Harmonic Overdrive Experience.


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## lrgaraujo (Sep 19, 2021)

Hey Chuck, that's a super nice design! Are you familiar with the Lab Series L3 amp? The preamp shares some similarities with your design (jfet input, cd4007 gain), but runs on -15V, positive ground. Do you have any idea why the negative voltage would be preferred?


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## Chuck D. Bones (Sep 19, 2021)

I have not seen the L3 circuit, do you have a schematic?  I might have a better idea why they did something if I can see it in context.  There is nothing special about positive ground or negative ground.


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## lrgaraujo (Sep 19, 2021)

Sure, there you go:



			https://music-electronics-forum.com/filedata/fetch?id=831483&d=1382636822
		


If I'm not mistaken, they use some servos for biasing (but I could very well be mistaken)


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## Chuck D. Bones (Sep 21, 2021)

Interesting... For 5 out of the 6 inverters in the two CD4007s, they use only the P-channel devices, operating them single-ended.  For that configuration, using -15V power makes sense.  I believe they get more gain by running the MOSFET stages single-ended. They run the effects loop driver stage push-pull to get the extra current needed.  I run all of the CD4007 MOSFET pairs push-pull in my CMOS Distortion.  They use servos for biasing the JFET input amp and all of the single-ended stages.  Clever design. Complicated, but clever.


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## lrgaraujo (Sep 21, 2021)

Thanks for taking a look, Chuck! From what I could find, it sounds really sweet. From clean to pretty overdriven. I'm kind of obsessed with good sounding SS preamps, so I might try and recreate it (minus the reverb driver and recovery)


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## cooder (Sep 23, 2021)

Aion has the Lab L5 preamp if that's any comparison, I have not looked into any details:
https://aionfx.com/project/l5-preamp/


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## lrgaraujo (Sep 23, 2021)

The L5 is an awesome project! It takes a completely different approach (an OTA is used for distortion), but sounds really good as well! The multifilter stage is also really interesting


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## Chuck D. Bones (Sep 23, 2021)

Right.  Nothing like the L3, but interesting.


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## fig (Oct 18, 2021)

Can some kind soul point me to C16 on the schematic? I know it's 100nF, but for some reason I cannot find it. 

Thanks in advance.
,


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## carlinb17 (Oct 18, 2021)

fig said:


> Can some kind soul point me to C16 on the schematic? I know it's 100nF, but for some reason I cannot find it.
> 
> Thanks in advance.
> ,


Page 9 off of pin 8 of the 4558 schematic says 10nf if your talking about the l5 or 

Here for the L3 it is 100nf


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## fig (Oct 18, 2021)

Sorry, I forgot there were schematics flying in every direction..I am building..









...using Matt's board. Maybe I missed a revision?


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## carlinb17 (Oct 18, 2021)

fig said:


> Sorry, I forgot there were schematics flying in every direction..I am building..
> 
> 
> 
> ...


hmmm…maybe it’s like whenever I build something from ikea I have extra parts…


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## fig (Oct 18, 2021)

Good, then you don't see it either, whew! 😶‍🌫️


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## Chuck D. Bones (Oct 18, 2021)

Sorry for the confusion.  Matt's board is based on v6.2.1 which has a MID control.  Look at post #11 on page 1.  C16 was not shown on the schematic; it goes in parallel with C15.  Here's an updated schematic.


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## fig (Oct 18, 2021)

Hot dog, thank you sir! I figured it came off of C15 and went to ground, based on the silkscreen.


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## danfrank (Oct 19, 2021)

Hi.
The Maestro Fuzztain (MFTZ-1) uses a 4007 in the Audio path. Lectric FX just came out with a clone board. Their build docs has a schematic. I think the 4007 is used for distortion.


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## Chuck D. Bones (Oct 19, 2021)

Found the MFZT-1 Service Manual.
According to the schematic, the 4007 is used as a voltage-controlled resistor in the compressor.  It is not used to make distortion.


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## Elijah-Baley (Oct 19, 2021)

fig said:


> Sorry, I forgot there were schematics flying in every direction..I am building..
> 
> 
> 
> ...


Excuse me, I seen this schematic and I noticed something weird/knew. Those transistors mosfet type symbol with CD4007 label.
I use Tina TI software to draw schematics, but I can't insert CD4007 to draw the Red Llama schematic.
Is that maybe a sort of trick to "emulate" a CD4007?

Edit: I'm sorry. I confused CD4007 with CD4049UBE.  Can I do anything, awnyway to emulate it?


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## fig (Oct 19, 2021)

Elijah-Baley said:


> Excuse me, I seen this schematic and I noticed something weird/knew. Those transistors mosfet type symbol with CD4007 label.
> I use Tina TI software to draw schematics, but I can't insert CD4007 to draw the Red Llama schematic.
> Is that maybe a sort of trick to "emulate" a CD4007?
> 
> Edit: I'm sorry. I confused CD4007 with CD4049UBE.  Can I do anything, awnyway to emulate it?


I found the parameters for the TINA-TI MOSFET model, but I'm not sure if it is what your looking for. Do you know if the LTSpice models are compatible?


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## Chuck D. Bones (Oct 19, 2021)

Elijah-Baley said:


> Excuse me, I seen this schematic and I noticed something weird/knew. Those transistors mosfet type symbol with CD4007 label.
> I use Tina TI software to draw schematics, but I can't insert CD4007 to draw the Red Llama schematic.
> Is that maybe a sort of trick to "emulate" a CD4007?
> 
> Edit: I'm sorry. I confused CD4007 with CD4049UBE.  Can I do anything, awnyway to emulate it?


When you say "emulate," do you mean simulate?  I have LTSpice models for the MOSFETs inside the CD4007 & CD4049.  I don't know anything about TINA-TI or if the models are compatible.


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## Elijah-Baley (Oct 20, 2021)

Thanks for your replies, guys.
I'm looking for a CD4049UBE spice to use with Tina TI to draw the schematic of the Red Llama and to see the frequency response, etc. The Red Llama schematic is very simple, and I did some experiments on breadboard, but I'd like to draw it, anyway.
I don't know I can find somewhere the CD4049UBE spice, or I can "build" it with its inner schematic.



fig said:


> I found the parameters for the TINA-TI MOSFET model, but I'm not sure if it is what your looking for. Do you know if the LTSpice models are compatible?
> 
> View attachment 17239


Do you think I can use that to get or to create a spice of the CD4049UBE? I don't know if I really can.


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## fig (Oct 20, 2021)

Spice component models are mostly text files with component parameters and specs that can be edited. Mouser and others include Spice model documents along with the normal data sheet. 
If you place the file in your library include path, it should find it as a listed component.

Here is a link to the SPICE model for the CD4049UB from Mouser. Hope it helps!

http://www.ti.com/litv/zip/schm019


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