presenting the Schizoid Face

Stompboxes circuits published in magazines, books or on DIY electronics websites.
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pinkjimiphoton
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Post by pinkjimiphoton »

first and foremost manfred, i hope you are doing much better my friend.
thanks so much!! i will add them to my archive for the project and maybe get some boards made.
awesome really appreciated!!
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Post by aquataur »

Gentlemen,
this thread is a bit dusted, nevertheless... My request has no better place to go.

Does anybody have the current schematics saved? All images are blurred due to the picture host´s questionable politics. This is a PITA.
Jimi, I want to thank you for all the effort.

Greetings, Helmut.

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Post by pinkjimiphoton »

here ya go
Attachments
stupid 3 color led trick 4 leds.png
SchizoidFacePCB_SolderSide.BMP
SchizoidFacePCB_SolderSide.BMP (426.62 KiB) Viewed 496 times
SchizoidFacePCB_componentsSide.BMP
SchizoidFacePCB_componentsSide.BMP (426.62 KiB) Viewed 496 times
SchizoidFacePCB.pdf
(8.65 KiB) Downloaded 14 times
dB!!FX PjP Schizoid Face 1.4 2017.png
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Post by aquataur »

c´est magnifique
thanks a thousand times. I let you know about the comings out.
-h

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Post by pinkjimiphoton »

as long as the npn's are between about 160hFE and 250hFE, you should be good.. you may need to play with the emitter resistors slightly outside that ballpark. all the led's were kinda overkill lol, but looked cool changing from a smiley face to a frown ;)
you may wanna consider giving them their own tap off the power supply really well filtered, as imho led's can tend to add a lot of noise to the circuit, and "hash" when your guitar knob is all the way down by leaking all kinds of crap to the ground rail. leds are fucking weird, they also act as transducers sorta... sensitive to light, rfi, hum etc...i cannot claim to even begin to understand all that stuff, i just know it happens ;)
i hate turning my guitar off and suddenly it sounds like bacon frying inside an old tube tv ya just put a stratomobob thru ;)

minus the led's, it WILL fit in a 1590a if ya lay it out right and use 9mm pots and a toggle instead of a second footswitch.
when ya get it together, i set the bias up like this... crank the fucker full blast... plug your guitar in, and turn it down almost all the way, then adjust the c bias resistor if ya need to, but it should bias up good with the chosen values. 100r e to ground resistor is fine if ya don't have 47r. if ya need to, of course add a b10k trimmer for the 8.2k resistor on q2 instead, give ya a wider range of bias choices... if ya go that way, turn the guitar down to about 1-2, then bias for the clearest tone you can get... that will "tune" it to your guitar and should give the best sweep from crystaline and cleanish thru overdrives to full on fuzz.

IF you need more balls out of it, add another footswitch and switch the 47n output cap between sides of the 8.2k or b10k trimmer... the stock ff is with the output cap to the top of the q2 c bias resistor, but if you switch the output cap to the other side, the junction of the 8.2k and c, you get a good volume bump that can be adjusted somewhat by the biasing as well. i call that the fuzzface + mod. its great. makes the beast far more gnarly and loud, which you may or may not like. i know three footswitches is a lot for a fuzzface, but... in this case, could give a really versatile one.

just weird shit i did with the circuit in various incarnations, if ya wanna mess with it more. have fun, and for sure, let us know how ya makes out brother aquataur. peace to you my friend, and happy 2020!
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Post by aquataur »

Thanks brother Photon.
I did intuitively incorporate some of the things you talk about in a PCB I rendered today. It´s gonna fit into a 125B case, even has a buffer in front. I like my effects buffered, thus the "poker face" I once did (think the web site does not work currently, have to look into this, but rather wield the soldering iron...).
I can jumper select this for an a/b comparison. You wanna have some 10k drive resistance though, everything else will sound horrible. FF input I read is current driven so I fake a current drive with a series resistance. I guess Fuller did the same with a resistance in series with the input.
Run the guitar with a buffer otherwise it will get dull beyond bearableness upon diming. Also no funny incompatibilites due to impedance mismatch.

Anyway, I will see if this is for better or worse.

With all the discrete effects I did recently I went to extreme pain with the powersupply. Like tube amps, they have their stages decoupled with R/C combinations in the power rail. Read this somewhere and makes sense, does not harm in the worst case and costs nothing but a little PCB space, but may be overkill. The "inventor" of this maintains a site in France, he makes all sorts of GE effects. Reckons he brings noise down a bit.

I also had the indicator LED´s in some circuit decoupled with an RC to the switching side, so as do alleviate a thump caused by inrush currents. May be overkill too.

I like the idea of the Jekyll / Hide smiley, I put them LEDs on a separate little PCB, utilizes the scarce place better. If this makes problems, I can do something about locally.

May take a few days until I get the board done and on the bench, but I will report back.

-h

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Post by pinkjimiphoton »

can;t wait to see/hear it!!

another great trick you may like, make a bass cut filter out of a .0022 cap and a 25k-50k pot. wire this between the footswitch and the input cap... then you can dial out the bass when the fuzz is dimed without needing the buffer, and make it more of an overdrive that's real responsive.
i forget which pins to use lol, but connect two of the lugs on the pot together with one cap lead, then put the other side of the cap to the third one. input on one side, output on other... it works great with the fuzzface, i actually build that stuff into my guitars!

very psyched, i hope you have a blast with it!
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Post by aquataur »

Cést Voilá.
The PCBs are made - and work :D
All worked out as expected. More on that once the pedal is complete, if there is interest.

Sound: as predicted - good. I cannot comment on the GE sound, since I do not have such a unit. I do however have a hybrid fuzz-a-like, that sure is in the same ballpark.
Its tone into a cleanish amp is not overwhelmingly fizzy or bright. A good sign. So no taming caps needed.
However, no distortion unit I had up till now sounds as expected (or shown in videos) into a clean brittle amp, particularly fuzz face type, so with a benign overdrive in front of the amp or the amp already smoldering it really shines.

I associate fuzz faces with a little farting out, so the LP filter in the front really helps. I like a tight bottom :applause:
Speaking of bass-cut:
pinkjimiphoton wrote:it works great with the fuzzface, i actually build that stuff into my guitars!
I have a four position cap filter built into my guitar for the very purpose, but the circuit you mention, which happens to be built into my G&L bass guitar, works well too and I might make the change for the guitar as well. Note in the attached picture, a cap works into the 250k Volume pot, functioning as a HP filter. When you turn the pot, the cap gets gradually short-cut.

Technical gossip: All MPSA06 transisors I see have a gain of 100. Confuses me that you speak of 215.
Anyhow, I had to use what was there. I had some 2N2222s (gain around 190), but a PN2369A in the first position (gain around 60) sounds better to my ears. (Note this may change after listening with a "fresh" ear :roll: ). This is BTW coincident with findings for vintage units.
I played with the emitter resistors, Pos.2 is unchanged, Pos.1 sounds better with about half. (As you said, doubling the gain, doubling the emitter resistor).
The collector resistor of Pos.2 was trimmed by ear, gets very metallic towards 10k, settles at 3.4k. Appears low to me but sounds best. Below gets more into RAT territory.

More on that once I have the PCB housed with all the bypass switching and A/B-ing.
Attachments
Bass Control as used in G&L basses
Bass Control as used in G&L basses
detail bass cut.jpg (41.13 KiB) Viewed 442 times

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pinkjimiphoton
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Post by pinkjimiphoton »

outstanding bro!
can't wait to hear it or see it.

yeah, the mpsa06 papers usually say 100hFE, but in practice, i always seem to get three ranges... around 100, around 175 and around 215. but as you said, easy to adjust the e resistors to make it sing. really glad you dig it. look forward to your progress!
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Post by aquataur »

It drives me mad having to wait on such ridiculous parts like a case.
I want the thing boxed up and silent before I make a recording.

Experience up till now
: FF does not sound farty, both sections eminently usable, reacts well to the volume pot.

A word on that. Things like cleans up well and reacts to volume pot are musicians expressions that could not be farer from a standard (norm). That is totally subjective.
Volume pots come in variety, some recommend linear ones, some log. Even log is not standardized to my experience.
Then. Do they have a 250k, a 500 k pot? Makes a difference. When the volume knob is dimed, series resistance into the FF increases differently in those two cases.
Consequently, a Les Paul should clean up faster. It is those imponderabilia that make things hard to compare. I have written about that in my web pages. They work again so look them up if this interests anybody.

I personally like to eliminate imponderabilia wherever I can. I thus make my FF´s with a buffer in front. Wait before you tear your hair folks. Consider, that a stock pickup has some 10k source resistance. Insert a 10k resistor between buffer and FF and you are done. As mellow as it can be. But agreed, with some 100 Ohms drive impedance the FF will sound horrible. This is what happens if you drive the FF with a stock buffer.
I do not want to evangelize anybody, but try it.

Back to "cleaning up".
Brother Jimi, although not conducting a "scientific" laboratory experiment under repeatable conditions for your GE/SI comparison, this is intuitively significant, since environment variables such as guitar impedance and subsequent amp are unchanged during the comparisons. They indeed appear indistinguishable on the video.

However, for my specimen I have no possibility to compare. Some different transistors call for adaptations in the resistors. Presumably similar though.
I read elsewhere that with both types this "cleaning up" business is rather subjective. Clean is not clean for everybody, clean is not clean after prolonged exposure to loud music, particularly to distorted signals.

Hard to say with those protagonists like Hendrix, what is clean, too.
I find it "fairly" clean on low settings, but never undistorted.

I have some other dirt pedals that do clean up faster, but those probably do not have this graceful transision into distorted territory. I guess this is the beauty of a fuzz face.
Keep you informed.
-helmut

Edit: an experiment. I run a long cable into the next room, door closed to play the guitar from outside into my Peavey Bandit clean channel, very loud, T-dynamics (power stage compression) fully dimed, no pedals inbetween. FF exhibits no excessive highs (senza C-B caps!), great dynamic sensitivity, no typical FF farting. Veeeery low noise. Cheers!

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pinkjimiphoton
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Post by pinkjimiphoton »

in this case, its preset to stay fairly sweet, but i agree, won't necessarily clean up completely. if ya wanna do that, what i do is replace the c resistor on q2 with a b10k trimmer, then turn the guitar down to where it just kicks in, maybe around 1 on the guitar knob... then adjust the bias for the "cleanest" sound i can get. usually that gets you a nice overdrive around 4 or 5 and crank it right up to its full fuzzy goodness. works trick.
thanks for the info on your findings, and the info about why/how the ff cleans up as it does, i am sure others beside myself will benefit from your hard work.

can't wait to fuckin hear it! let me know if ya order boards, i may take a couple off your hands ;)
"When the power of love overcomes the love of power the world will know peace."

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pinkjimiphoton
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Post by pinkjimiphoton »

in this case, its preset to stay fairly sweet, but i agree, won't necessarily clean up completely. if ya wanna do that, what i do is replace the c resistor on q2 with a b10k trimmer, then turn the guitar down to where it just kicks in, maybe around 1 on the guitar knob... then adjust the bias for the "cleanest" sound i can get. usually that gets you a nice overdrive around 4 or 5 and crank it right up to its full fuzzy goodness. works trick.
thanks for the info on your findings, and the info about why/how the ff cleans up as it does, i am sure others beside myself will benefit from your hard work.

can't wait to fuckin hear it! let me know if ya order boards, i may take a couple off your hands ;)
"When the power of love overcomes the love of power the world will know peace."

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Post by steben »

aquataur wrote:It drives me mad having to wait on such ridiculous parts like a case.
I want the thing boxed up and silent before I make a recording.

Experience up till now
: FF does not sound farty, both sections eminently usable, reacts well to the volume pot.

A word on that. Things like cleans up well and reacts to volume pot are musicians expressions that could not be farer from a standard (norm). That is totally subjective.
Volume pots come in variety, some recommend linear ones, some log. Even log is not standardized to my experience.
Then. Do they have a 250k, a 500 k pot? Makes a difference. When the volume knob is dimed, series resistance into the FF increases differently in those two cases.
Consequently, a Les Paul should clean up faster. It is those imponderabilia that make things hard to compare. I have written about that in my web pages. They work again so look them up if this interests anybody.

I personally like to eliminate imponderabilia wherever I can. I thus make my FF´s with a buffer in front. Wait before you tear your hair folks. Consider, that a stock pickup has some 10k source resistance. Insert a 10k resistor between buffer and FF and you are done. As mellow as it can be. But agreed, with some 100 Ohms drive impedance the FF will sound horrible. This is what happens if you drive the FF with a stock buffer.
I do not want to evangelize anybody, but try it.

Back to "cleaning up".
Brother Jimi, although not conducting a "scientific" laboratory experiment under repeatable conditions for your GE/SI comparison, this is intuitively significant, since environment variables such as guitar impedance and subsequent amp are unchanged during the comparisons. They indeed appear indistinguishable on the video.

However, for my specimen I have no possibility to compare. Some different transistors call for adaptations in the resistors. Presumably similar though.
I read elsewhere that with both types this "cleaning up" business is rather subjective. Clean is not clean for everybody, clean is not clean after prolonged exposure to loud music, particularly to distorted signals.

Hard to say with those protagonists like Hendrix, what is clean, too.
I find it "fairly" clean on low settings, but never undistorted.

I have some other dirt pedals that do clean up faster, but those probably do not have this graceful transision into distorted territory. I guess this is the beauty of a fuzz face.
Keep you informed.
-helmut

Edit: an experiment. I run a long cable into the next room, door closed to play the guitar from outside into my Peavey Bandit clean channel, very loud, T-dynamics (power stage compression) fully dimed, no pedals inbetween. FF exhibits no excessive highs (senza C-B caps!), great dynamic sensitivity, no typical FF farting. Veeeery low noise. Cheers!
I've built faces with common collector stage sin front (buffer) followed with a pot in series. Does work. But it doesnt give the full treble cut effect at full guitar volume. its different, rather a blend of fuzz and distortion. Closer to the 3 knob tonebenders.

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Post by aquataur »

steben wrote:(...) 3 knob tonebenders.
Mine does not sound like a tonebender. Be your own judge:
http://aquataur.hilpold.net/aquataur/mu ... _fuzz.html

The typical 3 transistor tonebenders have a 10k resistor in the driving stage. In a common emitter stage this will yield a 10k source impedance, since this is typically equal to the collector resistor. However, look close, this hast monstrous gain on it.
The version I used is an emitter follower, that in it self has a drive impedance in the 100 Ohms range, but has a series resistance to increase the total impedance.
This has no gain on it.
Maybe if such a ciruit is hit with enough gain, and nothing to mellow its tone out afterwards (such as an overdriven amp), it would indeed reach into tonebender territory.
FF´s are all about the right set of gains.
Don´t get hung up on circuits that somebody put together sometimes. Nothing is set in stone.

Verdict: Successful build

-h

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Post by aquataur »

By common request :D I made a few additional recordings, FF unbuffered, buffered hard driven, buffered 10k, unbuffered and thumped down with a clean boost á la Tonebender.
Have fun.

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