been a while, thought i'd post something new...

[GGBB]

Still see a problem.  What causes current to flow through R4 or the snarl pot?  If the pot has an effect, it is because the actual circuit is different from the design.

Me thinks that lug 1 should go to ground, no? Maybe an oversight on the drawing?

I'm not the only one with reservations then. Jimi? Are you sure there's nothing connected to lug 1 of the snarl pot and C8 is connected to lug 3 and R4 straddles lugs 2 and 3???

[pinkjimiphoton]

Still see a problem.  What causes current to flow through R4 or the snarl pot?  If the pot has an effect, it is because the actual circuit is different from the design.

Me thinks that lug 1 should go to ground, no? Maybe an oversight on the drawing?

I'm not the only one with reservations then. Jimi? Are you sure there's nothing connected to lug 1 of the snarl pot and C8 is connected to lug 3 and R4 straddles lugs 2 and 3???

close... first thing i noticed is the saturate pot you have wired as a pot, but it's only the top and middle lugs being used in my layout/build/hand drawn schematic. i DID try it like you have it and it doesn't work the same. it's gotta be a variable resistor.

It is wired as a variable resistor except I connected lugs 1 & 2 together so that if the pot wiper fails you still have the pot working at max value rather than an open circuit.

edit: looking at it, the only thing i think i see is the 1u cap i used was an electro,  the + side would be to the left in case anyone builds it and doesn't have any caps that big that aren't electrolytic. other than that.... at a third look.... LOOKS GOOD!

Good point - I put a film there with plenty of room around it since they are getting more common now at 1uF. I'll mark the polarity on the final version.

EDIT:

the ac176 pinout is marked with a tab to c. tough call, in this case, the ge reads the same either way, so if it sounds farty one way, turn it 180 degrees i guess. the layout matches what i built. i believe.

I put extra pads there so it can easily be flipped.

Still see a problem.  What causes current to flow through R4 or the snarl pot?  If the pot has an effect, it is because the actual circuit is different from the design.

ok, i just looked at this thing, even took a couple pics of it. the board is messy, cuz my son populated and soldered it (his first). it was built using an EKI fuzz kit pcb. the circuit is a hack on that originally.

it is wired like i said. there IS  a possibility lugs 1 and 3 are "backwards". i have read til i'm blue in the face "how to wire pots" and it's often wrong. i go by the functionality of the pot as 3 on top and 1 on the bottom with the lugs facing right from the back of the pot. SOMETIMES it may be reversed in action from expected... particularly when using a pot as a variable resistor/rheostat than a potentiometer.

in this case, current flow is bleeding thru  the cap to ground right off the input to the baalz control. almost like you may wire a guitar with a passive tone control.

remember, caps have ESR. if you vary the amount of resistance in parallel with a cap to ground as in this case, it changes the tone and attack characteristics of the audio i think by making the circuit think the cap is changing value... in this case, if you connected the unused lug to ground, you would have a volume control that gets brighter as you raise it. we don't want that. we want it to be the cap to ground to bleed off some treble. it may seem different, but it will indeed work. in my case, i grounded it right (the cap) to the back of the pot.

so i'm assuming the esr changing is what affects the tonal change. it does get quieter ccw, and louder and brighter cw. all the way ccw you get a significant volume drop in some settings, easily covered by the baalz pot to regain volume.  and again, all parts of this are highly interactive in weird ways.

try it on a breadboard. it indeed does work. it may seem "wrong" but of course it should, it's not the usual way of doing things. i am no ee, i am a monkey with a @#$%in' breadboard hacking away at shit til i like the way it sounds.

and i DID use this live last nite... worked great. more overdrivey at stage volumes, sounds great with a fuzzface front end.

almost every action on this pedal is about feedback of some kind... there's no potentiometer bleeding anything to ground for volume control.
the saturation control changes the tone by changing the biasing of the transistors.
the baalz control changes the volume by messing with the feedback and biasing of the transistors.
the snarl control changes the tone/distortion level by changing how much high end is bled to ground thru the 100n cap .

i don't understand all aspects of this myself, so some is obviously conjecture. all i can tell ya is it works.

i mean... do the tone controls in your guitar work? yep. almost the same thing in this case, but we're messing with the feedback of the cap to ground, and the resistance.... oy vey... all i can tell ya is try it. it works. if you tie the final pin to ground, it won't work right.

we often think of the convention of trimmers as pots. well, you can also use them as rheostats. that is what i'm doing here. and yes, it does work. tieing the unused pin to wiper works, but it's a potentiometer, not a rheostat in that case.

anyways... there is a wire from the input of the baalz pot (red for mojo of course) that goes to the snarl pot. from the back, with the pins facing right,  there is a 3.9k resistor between top (input) of pot and wiper. at the top of the pot also is the 100n cap with the other end tied to ground.
the final pin is not connected. here's a pic.



while i'm at it, here's a couple more of the guts. it ain't pretty, but it matches what i drew

pcb from the back



uttsgay



top of the board



like i said, try it on a breadboard. it indeed does work. it may be "outside the box" but i don't care about crayoning inside the lines.

if it sounds good.... to me... it IS.

so.... no, the circuit is NOT different from what i posted, and yes, it DOES work. as shown. guess i'm gonna have to fire up the video cam downstairs in a little bit.

stay tuned...

[pinkjimiphoton]

chris on the other forum has built this... he DID make some changes, and got the expected results (as i'd already tried tieing lug one to ground, etc, the master volume etc...)

anyways, a c/p from fsb

Hi Jimi

Good to see you here again.  Terrible news about the tumour, but great that it got fixed.

I've just breadboarded your latest creation (using a 10k pot and no resistor for the "snarl" and connecting lug 1 to ground as you surely intended) and omitting the "mojo" capacitor.  I used an unmarked Russian Ge device for Q2 and a BC107 (lots of metal-can mojo) for Q1.  I added a 47k output pot - I got quite a big boost from the thing.  I prefer it without the diodes connected (and the huge volume loss you get with them switched in), but I tried adding a pair of LEDs in series with the 1N60s.  You still get the rounded edges from the 1N60s, but with bigger amplitude.  Now that sounds better!  I found that the "saturate" control was causing instability towards maximum resistance, but that could be fun if you want it to squeal!  I set the bias at just under 5V - that's where it sounded best to me.

This one's going to get boxed up, I think......

hi chris,
nice to hear from ya! thanks for building this...

yes, it IS loud... i don't use the pots all the way up, so i didn't need the volume control... i thought it sounded fuzzier with the sat control up, and the baalz lower. but if ya crank all three, i can see a need for the master volume.

actually, the snarl pot is different.. i didn't connect pin 1 to ground, cuz it's using it as a rheostat instead of a potentiometer... the snarl control if it goes to ground will sound different (i did try it that way)... i THIMK the thing works by changing the ESR of the pot.

i agree on the diodes... big volume drop, but easily compensated for... and at some settings quite cool i thought.

the saturate pot at max resistance (full ccw) with the snarl control also full resistance (ccw) it's REAL close to instable for sure! on mine, it has a notch you can sweeep thru as ya mess with the bias some... but all the way ccw on sat and snarl (as i drew it) i get this cool octave up WITH fundamental, and it gets very synthy sounding... somewhere between strings and woodwind kinda sounds.

i was mimicking violins and cellos with it, last nite i used it live and got a passable enough flute sound that my drummer thought someone in the audience was playing the flute on "locomotive breath"... very cool.

do me a favor bro... try disconnecting the ground from pin 1 of the snarl control, and try it as the rheostat rather than bleeding stuff to ground. you can always put it back if ya like, obviously.   i wanna see if what i built is repeatable for someone else.

for all intents, all it is is a passive guitar style (almost) tone control.

i like the led trick... i tried it too, but liked it better with the ge. i too prefer them disconnected for most things, BUT they work as a simple compressor when on....they let ya sweep the saturate control without getting a massive volume increase from ccw to cw (full resistance to minimal resistance)... when off, it gets LOUD when ya crank the sat control. they also sound good on when the sat and snarl are fully ccw... helps keep the volume more consistent.

i like the idea of adding the leds tho WITH the ge.. you get a nice tone that way, i did that on a different circuit recently.

try it if it'sm still on the breadboard as shown minus the mods you made.... at half way up it should sound like a decent marshall-esque kinda overdrive. from there, you should be able to tune in all kindsa stuff. adding a master as you did will let ya crank it more and then dial it back... i just didn't wanna put a 4th pot on it.

that said, i found a 10k-ish pot between diodes and ground with a switch between was also kinda valid... you could mess with the amount of compression that way.

you should be able to get fuzz, overdrive, multi octave (fundamental and oct up) kinda sounds fairly easily.

of course, the number of vegamatic switch functions is entirely up to the builder

[Ripdivot]

Still see a problem.  What causes current to flow through R4 or the snarl pot?  If the pot has an effect, it is because the actual circuit is different from the design.

Me thinks that lug 1 should go to ground, no? Maybe an oversight on the drawing?

I'm not the only one with reservations then. Jimi? Are you sure there's nothing connected to lug 1 of the snarl pot and C8 is connected to lug 3 and R4 straddles lugs 2 and 3???

close... first thing i noticed is the saturate pot you have wired as a pot, but it's only the top and middle lugs being used in my layout/build/hand drawn schematic. i DID try it like you have it and it doesn't work the same. it's gotta be a variable resistor.

It is wired as a variable resistor except I connected lugs 1 & 2 together so that if the pot wiper fails you still have the pot working at max value rather than an open circuit.

edit: looking at it, the only thing i think i see is the 1u cap i used was an electro,  the + side would be to the left in case anyone builds it and doesn't have any caps that big that aren't electrolytic. other than that.... at a third look.... LOOKS GOOD!

Good point - I put a film there with plenty of room around it since they are getting more common now at 1uF. I'll mark the polarity on the final version.

EDIT:

the ac176 pinout is marked with a tab to c. tough call, in this case, the ge reads the same either way, so if it sounds farty one way, turn it 180 degrees i guess. the layout matches what i built. i believe.

I put extra pads there so it can easily be flipped.

Still see a problem.  What causes current to flow through R4 or the snarl pot?  If the pot has an effect, it is because the actual circuit is different from the design.

ok, i just looked at this thing, even took a couple pics of it. the board is messy, cuz my son populated and soldered it (his first). it was built using an EKI fuzz kit pcb. the circuit is a hack on that originally.

it is wired like i said. there IS  a possibility lugs 1 and 3 are "backwards". i have read til i'm blue in the face "how to wire pots" and it's often wrong. i go by the functionality of the pot as 3 on top and 1 on the bottom with the lugs facing right from the back of the pot. SOMETIMES it may be reversed in action from expected... particularly when using a pot as a variable resistor/rheostat than a potentiometer.

in this case, current flow is bleeding thru  the cap to ground right off the input to the baalz control. almost like you may wire a guitar with a passive tone control.

remember, caps have ESR. if you vary the amount of resistance in parallel with a cap to ground as in this case, it changes the tone and attack characteristics of the audio i think by making the circuit think the cap is changing value... in this case, if you connected the unused lug to ground, you would have a volume control that gets brighter as you raise it. we don't want that. we want it to be the cap to ground to bleed off some treble. it may seem different, but it will indeed work. in my case, i grounded it right (the cap) to the back of the pot.

so i'm assuming the esr changing is what affects the tonal change. it does get quieter ccw, and louder and brighter cw. all the way ccw you get a significant volume drop in some settings, easily covered by the baalz pot to regain volume.  and again, all parts of this are highly interactive in weird ways.

try it on a breadboard. it indeed does work. it may seem "wrong" but of course it should, it's not the usual way of doing things. i am no ee, i am a monkey with a @#$%in' breadboard hacking away at sh*t til i like the way it sounds.

and i DID use this live last nite... worked great. more overdrivey at stage volumes, sounds great with a fuzzface front end.

almost every action on this pedal is about feedback of some kind... there's no potentiometer bleeding anything to ground for volume control.
the saturation control changes the tone by changing the biasing of the transistors.
the baalz control changes the volume by messing with the feedback and biasing of the transistors.
the snarl control changes the tone/distortion level by changing how much high end is bled to ground thru the 100n cap .

i don't understand all aspects of this myself, so some is obviously conjecture. all i can tell ya is it works.

i mean... do the tone controls in your guitar work? yep. almost the same thing in this case, but we're messing with the feedback of the cap to ground, and the resistance.... oy vey... all i can tell ya is try it. it works. if you tie the final pin to ground, it won't work right.

we often think of the convention of trimmers as pots. well, you can also use them as rheostats. that is what i'm doing here. and yes, it does work. tieing the unused pin to wiper works, but it's a potentiometer, not a rheostat in that case.

anyways... there is a wire from the input of the baalz pot (red for mojo of course) that goes to the snarl pot. from the back, with the pins facing right,  there is a 3.9k resistor between top (input) of pot and wiper. at the top of the pot also is the 100n cap with the other end tied to ground.
the final pin is not connected. here's a pic.



while i'm at it, here's a couple more of the guts. it ain't pretty, but it matches what i drew

pcb from the back



uttsgay



top of the board



like i said, try it on a breadboard. it indeed does work. it may be "outside the box" but i don't care about crayoning inside the lines.

if it sounds good.... to me... it IS.

so.... no, the circuit is NOT different from what i posted, and yes, it DOES work. as shown. guess i'm gonna have to fire up the video cam downstairs in a little bit.

stay tuned...

I would say you are using lugs 2 and 3 of the snarl pot with lugs 1 and 2 shorted together.

[GGBB]

vary the amount of resistance in parallel with a cap to ground as in this case

But that's the thing - the way it looks (diagrams and pic) is that the snarl isn't in parallel with anything - it goes from one end of the cap to nowhere. To be in parallel, both sides of the cap would have to connect to the snarl control or to something in common. It's as if you connected a resistor from one point back to the same point - that's what you have except that the resistor is the 3.9k resistor in series with the snarl pot wired as a variable resistor - they just form a loop of resistance connected at one point to the circuit but otherwise leading to nothing.

I would say you are using lugs 2 and 3 of the snarl pot with lugs 1 and 2 shorted together.

I'd say 1 and 2 are used and 3 is unconnected, but I can't be totally sure from that pic.

[pinkjimiphoton]

vary the amount of resistance in parallel with a cap to ground as in this case

But that's the thing - the way it looks (diagrams and pic) is that the snarl isn't in parallel with anything - it goes from one end of the cap to nowhere. To be in parallel, both sides of the cap would have to connect to the snarl control or to something in common. It's as if you connected a resistor from one point back to the same point - that's what you have except that the resistor is the 3.9k resistor in series with the snarl pot wired as a variable resistor - they just form a loop of resistance connected at one point to the circuit but otherwise leading to nothing.

I would say you are using lugs 2 and 3 of the snarl pot with lugs 1 and 2 shorted together.

I'd say 1 and 2 are used and 3 is unconnected, but I can't be totally sure from that pic.

guys, what i described is what i built, and yes, it definitely works. instead of arguing with me about how it can't work, @#$%in try it

in the pic, as i described, looking from the back of the pot (not the shaft) with the lugs facing right, top being 3 , wiper being 2, and the last one being 1, the 3.9k resistor is between wiper and pin 3. pin one is NOT CONNECTED to anything. the cap is connected to pin 3 of the snarl control on one side, and to ground on the other. it comes off the bottom of the pcb (red wire in the second pic) from the node where the baalz pot input (pin 3 again) connects to the circuit board. it is in parallel with the baalz pot.

you guys are thinking potentiometer. it's being used as a rheostat, not a potentiometer.  i'm not shunting signal to ground via a ground connection on a potentiometer, i'm faking varying the size of a cap connected to ground by putting a variable resistance in parallel with the "input" of the cap.

i know it's unusual, and i know you may not have seen it before, but that is what i did. i will shoot video. or ya can breadboard it and find out for yourself. chris assumed i made a mistake, and grounded the unused lug. it becomes a volume control when you do that. that is not what i did, or what i was looking for it to do.

you can try it, but spare me the "it can't possibly work" shuck and jive (like when i made that ge overdriver with no voltage divider that "couldn't be done or work" or the op amp overdrive i made with for all intents a simple ge transistor switchable between a diode clipper and a fuzz in the feedback loop of the flying spaghetti monster *(which does work, i guess, as a bunch of peeps on tagboardeffects built it).....

by all means, think inside the box. i don't see a box, so i don't need to think inside it.

sorry, not to be a pissy asshole jerk, but either @#$%in try it or don't. i don't really care.
rant alert: this is becoming one of the reasons i stopped frequenting this place.
every time some people see something different they didnt think of or try for themselves, because it's different, people start pigpiling claiming that shit can't work, like my friend ryan's ge fuzz that led to my stupid experiments.... and yes, you can build a fuzz with ge without all the baubles and beads, and yes, it can sound good.

if ya don't believe me, fine. but if you're not gonna try it, fine too. do whatever the @#$% ya wanna do, but i''ve already said all i have to say on the matter and see no reason to endlessly repeat myself.

if ya try it and it works, so be it. thank you for taking a leap of faith. if ya try it and it DOESN't work, then i'll accept something is wrong.
but if you're not gonna try it, don't bust my baalz that it can't work, and go google the diffs between RHEOSTAT/VARIABLE RESISTANCE and POTENTIOMETERS.

i don't know shit about electronics. don't pretend to, probably never will. but i recognize that there's more than one way to skin a @#$%ing cat.

off to shoot video....  of the circuit i presented... which works, and pretty much as i described. the circuit has already been independtly built by mictester on the other forum, and it works.

i'll lay out on that, for now.

sorry to be an asshole, but i hate having the same question asked 30000000 times. finding mistakes? i am grateful when someone finds something i messed up on.

but this isn't a mistake, it's intentional.

end of rant.

\

[GGBB]

Sorry Jimi - didn;t mean to get on your nerves. I, and probably everyone else here, don't question that you know what sounds good, nor do I doubt that your snarl control does what you say it does. I am just trying to understand how, and to make the PCB so it works the way it is supposed to. I'll see if I can make certain variations on the theme optional via jumper.

[pinkjimiphoton]

sorry gord, didn't mean to be such a dick.

guess life is getting to me in general and making my temper wayyyyyy short, and i sincerely apologize.

i went down to the basement to my dungeon and dicked around a little bit and made a stupid pedal trick episode.
beware, i kinda let it all hang out

BUT i figured out (i think) why the snarl/tone control DOES work. it's all cuzza the resistor. i think it's a high pass filter, and variable. the resistor i believe makes it so there's always a connection between wiper and input, in parallel with the variable resistor of the snarl pot. while normally, you'd probably think of the cap having to hang off the wiper, cuz of the bleed thru the resistor it's always semi connected.... the cap, i mean. on one side, it sees 3.9k resistance PLUS whatever the pot is set at in parallel to the cap... i may be outta my mind here.. but for all intents, due to feedback bleed thru the resistor, the cap can go on either input or wiper and still be connected to the circuit.

like... one side is 3.9 k the other is the pot value divided by 3.9k.... the resistance with the cap is doing something, cuz it's variable. i may ask my friend wes to see what's going on with the oscilloscope.

but i THIMK the thing is we're thinking current flow with dc.... it goes one way, and one way only... nice and orderly, from + to -. easy breezy.

but... BUT... in AC, current flows both ways all the time. we think of it as a stream (particularly in dc) but it's really more like a cloud or field.

bear with me... i think i'm close here...

i think what's making it work is that it's influencing the audio somehow... which in amplification is AC, carried along for DC amplification.

look at the circuit... the snarl control in total is in parallel to the baalz control.  so there's already connections to ground... thru the 100r resistor, which "floats" not only the snarl and baalz control above ground, but also the emitters of both transistors.

i think something more is going on than meets the eye, and maybe i should reach out to paul or mark or rg or someone to suss this out.

but... that said... and it's in the video as it happened..
i went to the dungeon, popped her open, and verified the pot was as i described in value and hookup.

i also tried my meter to see if i had a connection to ground on the unused pin with my beeper. i did not show a resistance or any connection, tho i could "hear" the blow from the amp change when my meter pin was connected.

i tried connecting the bottom of the pot to ground via a jumper, and it still worked. it didn't work BEFORE, but it still worked. but not quite the same as when it's not connected to ground. so yeah, connect it i guess. i didn't. i can get sounds at the "bottom" of the pot i can't get with it grounded tho. it's in the video,  even me quasi apologizing.

it's long, and frank, and i probably f bomb a time or 300, what with me having it open and dicking around inside with the meter and such, but i think you'll be able to hear the weird tones from it.... some are REALLY cool. very synthy, reminds me of the boss t-bone project a couple years ago but not as touchy to dial in. can kinda mimic brass and woodwinds and strings with it... 

it's also INSANELY loud if you're the type who may like fuzzes dimed, which could be problematic for your neigbors across town, so ya MAY wanna consider a 50k standard kinda master volume off the output. again, caveat emptor.

gonna upload the video now... fast forward thru my yammering a bit if need be for the juicier bits.

[pinkjimiphoton]

ps... just to be positive, gonna make sure , i mean SURE that the snarl pot's one connection to the circuit other than earth is where i think it is while the video uploads... stay tuned. peace

[pinkjimiphoton]

here ya go, stupidest pedal trick yet

[stonerbox]

Totally off topic but DAUUMN that cello-emu sounds f-cking incredible Jimi!

[bluesdevil]

Welcome back, Jimi! Great to see you at it again..... now I'm off to hopefully score an AC176 somewhere.

[pinkjimiphoton]

thanks benjamin and bill.

yeah, it doesn't do the cello thing the same with the snarl pot grounded. but it still WORKS when it's grounded.
so beats me.

i checked it out again, to be positive, and yes, that stoner control snarl pot is wired as i said... it's a jumper right off  where the baalz pot is connected to the circuit board.

i DID, just now, add a master volume control. chris said he used a 47k, but i found a 50k or 100k pot seemed to change the interaction of the controls a bit... you couldn't just dime it the way ya can without it. so i used a bog standard 1meg linear tayda dealio, totally standard thing between the output of the board and the switch. can dial in some more fuzz and overdrive sounds that way too, and tame it a little. and half way up it sounds pretty good and is close enough for unity gain for  rocknroll.

if ya really want fun, stick a three knob ge tonebender in front of it. holy sheet.... i just got lost for a couple hours playing with it. thick and phat as hell, and ya can still get the interaction with the fuzz in front.. except it doesn't get clean and glassy, just turns down and stays crunchy and phat, but quieter. hell, i may build something with a toneblaster (my formerly sucky si/ge tonebender variant, also recently updated) and this as one circuit... is seven knobs too many?

also, ya may wanna consider using the "mojo cap" as hard wired, and switching the 470n cap in in parallel with a switch so ya can have a "slim or phat" control, kinda like using the input dealio of the os mutantes regulus on the arse end instead. in that case, i'd probably go with a bigger cap there, maybe 4.7n to 10n or so.

as always, don't get too hung on the transistors.. i'd advise socket and experiment. i DID try a darlington in q1 with some amusing results, and several ge's, different variants of ac176 and and even some silicon with some decent results. the gain matters most most likely, as the ge and si's of similar gains sounded a lot alike. neither was really edgy as i'd expected.. this thing is creamy smooth. with a touch of snarl.

anyways, that's my story, and i'm sticking to it.

[pinkjimiphoton]

fire up the wayback...

http://www.diystompboxes.com/smfforum/index.php?topic=103396.0

here's the best pic i could get with my phone of the hand drawn schematic



final weak pathetic possibility... the cap is hanging off the wiper thru the 3.9k resistor connecting it to the input, so there's always a minimum resistance of 3.9k before the cap? but the cap is tied to both sides of the pot THRU the resistor?

no idea. i give up. all i know is it works.

[kingswayguitar]

nice story and pedal jimi. "as you can tell it's loud" . love it!

[pinkjimiphoton]

i just just barely managed to squish in the master volume, it's ugly in there but man it sounds pretty good

[Mustachio]

Jimi! Man So sorry to hear about the health probs and the thumb, glad to see ya still keepn that fretboard warm. Your a corner stone man!

Loved the demo video man , I can always listen to you play its great stuff. That Swell effect is the motts!

Gonna have to give this one a try when I catch up on my todo list .

[pinkjimiphoton]

hope ya like it if ya build it.

i really really like this one, it does some really cool stuff when ya consider what it was... trying to find the original schematic so ya'll can see the differences.

the master volume is a worthy addition.

[midwayfair]

guys, what i described is what i built, and yes, it definitely works. instead of arguing with me about how it can't work, @#$%in try it

in the pic, as i described, looking from the back of the pot (not the shaft) with the lugs facing right, top being 3 , wiper being 2, and the last one being 1, the 3.9k resistor is between wiper and pin 3. pin one is NOT CONNECTED to anything. the cap is connected to pin 3 of the snarl control on one side, and to ground on the other. it comes off the bottom of the pcb (red wire in the second pic) from the node where the baalz pot input (pin 3 again) connects to the circuit board. it is in parallel with the baalz pot.

you guys are thinking potentiometer. it's being used as a rheostat, not a potentiometer.  i'm not shunting signal to ground via a ground connection on a potentiometer, i'm faking varying the size of a cap connected to ground by putting a variable resistance in parallel with the "input" of the cap.

Maybe everyone's confused because

THERE'S NO CONNECTION TO GROUND FOR THE SNARL POT ON THE SCHEMATICS

It's just a 3.9K in parallel with a pot, and the only connection for EITHER is the emitter. As drawn, neither component can possibly do anything. Jimi said he connected the cap to the back of the pot, so the pot's lugs must be connected to the back of the pot as well.

As long as lug 2 is connected to ground, then it will work exactly as you describe.

[digi2t]