# Friedman Pedals - a circuit comparison



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

[edited to add Little Debbie]

PedalPCB carries several Friedman pedals and for good reason, they sound great.  My 2nd PedalPCB build was a Brown Betty.  The Little Debbie, Dirty Sanchez, Brown Betty, Thermionic and Complex are all basically the same circuit with a few different component values and one or two knobs.

All have GAIN, BASS, TREBLE & VOLUME controls.
Dirty Sanchez, Brown Betty, Thermionic and Complex have a PRESENCE control.
Little Debbie, Dirty Sanchez, Brown Betty and Complex have a MID control.
Brown Betty & Thermionic have a TIGHT control.
Dirty Sanchez has a TIGHT switch.
Dirty Sanchez, Brown Betty and Thermionic have an internal gain trimmer.
Little Debbie has internal trimmers for Tight & Presence.

Thermionic has slightly higher gain and a little more bandwidth for more bite.  The Build Docs call out 1N5817 schottky diodes for the 3rd stage.  Some people use 1N4148s like in the other Friedman pedals.
Little Debbie, Dirty Sanchez & Brown Betty are in the middle gain-wise.
Complex has slightly lower gain and a mild treble boost at the end (C14/R20).

You can build any of the above on a Brown Betty board.  I like having the TIGHT knob, but I think a TIGHT switch will do the trick in most cases.  Some folks (you know who you are) like the sludgy sound and will leave TIGHT wide open.

If you want to see a side-by-side comparison of the Thermionic and Brown Betty schematics, look no further than the Thermionic Deluxe.  Channel A is a Thermionic with a MID control; Channel B is a straight-ahead Brown Betty.


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## Danbieranowski (Jan 8, 2021)

Great info Chuck! Just finished my second Brown Betty today.


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

Yep, no clean setting on that pedal unless you back the guitar volume way down.


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## Grubb (Jan 9, 2021)

Thanks for explaining this @Chuck D. Bones. I've purchased a Complex and the Thermionic Deluxe, so that should just about cover the range of Friedman tones from what you've said.


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

Yep, everything except the Buxom Boost.  I'm planning a Thermionic Deluxe build and I'll mod channel B to Small Box specs.

I forgot Little Debbie!  See top post for edits.


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## ErickPulido (Apr 5, 2021)

I have always wondered if any of the Friedman circuits can be mod to get closer to a Soldano SLO sound


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## Betty Wont (Apr 5, 2021)

Probably, with some frequency tweaking, but I don't think the Friedmans have the gain to get to SLO territory though. The closest by far I've gotten to the SLO is the Soldado project. I heartily endorse its gain and tone structure as authentic feeling and sounding.


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

Wampler makes a SLOstortion pedal.  He uses JFET Mu-amps for the distortion stages and opamps for tone shaping.  Here's a schematic from FSB.  Not much in common with the Friedman pedal designs.  The production pedals contain an independent opamp boost.  You can try adding it to the Wish List.  Hmmm, I see a breadboard project on the horizon...


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## ErickPulido (Apr 5, 2021)

Chuck D. Bones said:


> Wampler makes a SLOstortion pedal.  He uses JFET Mu-amps for the distortion stages and opamps for tone shaping.  Here's a schematic from FSB.  Not much in common with the Friedman pedal designs.  The production pedals contain an independent opamp boost.  You can try adding it to the Wish List.  Hmmm, I see a breadboard project on the horizon...
> View attachment 10794


I have to try it, I hope I can find some J201 coz smd is a no for me, thanks


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## Betty Wont (Apr 5, 2021)

ErickPulido said:


> I have to try it, I hope I can find some J201 coz smd is a no for me, thanks











						MMBFJ201 JFET (Pre-Soldered) - PedalPCB.com
					

JFET




					www.pedalpcb.com
				



These work awesome. Very in-spec and consistent.


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

I'll have to sub something else until I get some more J201.


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## Barry (Apr 5, 2021)

ErickPulido said:


> I have to try it, I hope I can find some J201 coz smd is a no for me, thanks


GuitarPcb had a few for sale


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

I believe that there is a typo on the schematic.  C18 should be 47nF, not 4.7nF.  Looks like the sweep on the TREBLE control will be better if it's A500K rather than B500K.  Some tweaking of R20 may be necessary, depending on Q5's Vp.


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## ErickPulido (Apr 6, 2021)

Betty Wont said:


> MMBFJ201 JFET (Pre-Soldered) - PedalPCB.com
> 
> 
> JFET
> ...


awesome


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## secretbuffalo (Oct 3, 2021)

Betty Wont said:


> Probably, with some frequency tweaking, but I don't think the Friedmans have the gain to get to SLO territory though. The closest by far I've gotten to the SLO is the Soldado project. I heartily endorse its gain and tone structure as authentic feeling and sounding.


What Soldano project are you referring to? I would love to build a Soldano style pedal.


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## joelorigo (Oct 3, 2021)

I believe he is referring to this, which he heartily endorsed to me









						Soldado Preamp - PCB Guitar Mania
					

Inspired by Soldano SLO 100




					pcbguitarmania.com


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## NickC (Oct 3, 2021)

I have build a thermionic and it sound fantastic, it will be in my live pedal board instead of my xotic sl drive.

in my experiential about high gain amp I can say that the soldano x88r is the tone I am looking for in a pedal and the friedman naked amp circuit would also be interesting ( I've read around that it's based on a Naylor super drive 60)


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## Chuck D. Bones (Oct 3, 2021)

joelorigo said:


> I believe he is referring to this, which he heartily endorsed to me
> 
> 
> 
> ...


Interesting circuit, no tone controls on its own; it's intended to be stacked with an EQ board.


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## NickC (Oct 24, 2021)

i was thinking what if i wanted to just simply add a mid control to the thermionic? @Chuck D. Bones  you know the way?


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## Chuck D. Bones (Oct 24, 2021)

The cleanest way to do it is buy a Brown Betty board and build it to Thermionic specs.

Another option is to stack a Thermionic and a VarioBoost.


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## NickC (Oct 25, 2021)

Chuck D. Bones said:


> The cleanest way to do it is buy a Brown Betty board and build it to Thermionic specs.
> 
> Another option is to stack a Thermionic and a VarioBoost.


I thought you could just add some components to the thermionic to bring out a mid control @PedalPCB what do you think about it?


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## Chuck D. Bones (Oct 25, 2021)

If adding some components was a practical option, I would have suggested it.  The MID control in the Friedman pedals is an active filter.  It required another opamp and there are no spare opamps on the board.


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## Danbieranowski (Oct 25, 2021)

Let's take this to the next level and walk Dan through adding a Tube Screamer circuit to his Friedman Runt 50 head so he doesn't have to run one in front of the amp!


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## megatrav (Nov 10, 2021)

Chuck D. Bones said:


> [edited to add Little Debbie]
> 
> PedalPCB carries several Friedman pedals and for good reason, they sound great.  My 2nd PedalPCB build was a Brown Betty.  The Little Debbie, Dirty Sanchez, Brown Betty, Thermionic and Complex are all basically the same circuit with a few different component values and one or two knobs.
> 
> ...


I know this is an old post, but what would you suggest to get the gain of the Little Debbie up to the Thermionic?
Basically I want to eventually build a Thermionic with a mid control if that is possible (like half of the deluxe version)


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

Easily accomplished.
Reduce R13 to 10K
Increase R6 to 100K
Decrease R15 to 2.2K
Decrease C8 to 120pF
Decrease C9 to 100pF


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## spi (Aug 10, 2022)

Resurrecting this old thread because my question seems relevant. 

I get that high-gain/low-gain change is using either 10K or 27K for R13.
I'm kind of curious why the various Thermionic based boards have 2 different cap values (I'm talking specifically about C8 and C9 if you reference the Brown Betty schematic).

Here's what I observed:


CircuitR13C8C9Thermionic10K120p100pT Deluxe Channel A10K120p220pT Deluxe Channel B27K120p220pDirty Sanchez27K220p220pBrown Betty27K470p220pLittle Debbie27K470p220pSmallbox27K120p220pAion Tempest27K120p220pGuitarPcb10K120p100pFuzzdog22K120p100p

My question is why do the variants (BB, LB) stray from the stock circuits?  Or even why does the Deluxe channels not match the stock Thermionic/DirtySanchez (they're close but not exact)?  Do these matter much in the circuit?  I guess they control some of the gain of high frequency?


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## Chuck D. Bones (Aug 10, 2022)

It's what you say, those caps tune the high-freq roll-off.  It may be difficult to hear the differences, depending on the control settings.  Friedman picked those values for a reason, but feel free to tweak them to your own preferences.

The gain setting resistor is R13 on the BB sch.


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## Robert (Aug 10, 2022)

Waaay back when the Thermionic was first drawn up the capacitors were monkeyed with a little as a band-aid to tame some oscillations that were occurring in some builds...   Eventually the layout was improved and the modified values were no longer needed and returned to the correct stock values.    After all, this was one of my first PCB layouts (intended for DIY building) so the fact that it worked at all is impressive enough.    

The differences in the hybrid pedals like the Little Debbie, and Brown Betty are most likely a result of these changes.   Since neither of those were a direct clone they weren't updated.

The others reflect the measured values.

It looks like GuitarPCB has the correct values as well.

The Tempest appears to be a hybrid similar in vein to the Brown Betty, so that would explain the differences there.

It's possible that the Fuzzdog values come from one of the "best guess" schematics posted on FSB before all of the components were measured out of circuit.


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## NickC (Sep 25, 2022)

in the little debbie if I wanted to use normal pots instead of the 2 trimmers ( for tight and presence) i would have to use linear or reverse ones


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## Chuck D. Bones (Sep 25, 2022)

I'd recommend reverse audio (C-taper) for both.  

If you want more gain, you can bump R6 up to 220K.


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## NickC (Sep 25, 2022)

thank you, basically i would like to have a thermionic + mid pot  in 125b enclosure 💪


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## Chuck D. Bones (Sep 25, 2022)

To make it like Thermonic, follow the details in post #16.


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## vmazz (Nov 3, 2022)

I’m curious about the closest pedal predecessor to these Friedman pedals   I like the response of the complex I’ve built. I know a lot of the amp in box pedals are fet stages.  These are ic stages   What other pedals stack ic stages similarly? Anyone know a history?


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## Chuck D. Bones (Nov 3, 2022)

Please ask this in the General Questions forum, not here.


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