build report w/ verified vero layout, IC fuzz from original fender fuzz wah

[pinkjimiphoton]

i had one of these, and REALLY dug the fuzz, and had asked if anyone could help me convert the fender fuzz wah circuit to just a fuzz...

gus smalley posted this:



which led to this:



it's even verified... i'd tried a similar layout a while back, but made 2 rookie mistakes.. was missing the 10k resistor going to the + input of the chip, and had b+ going to pin 8, not pin 7. 

so anyways, now it's built and verified.

how's it sound? i REALLY like it. very thick buzzy sustaining distortion, with a buffered clean that can be blended in.
you can use a 5089 or whatever, but i advise to socket the tranny and try a bunch of npn's. to me, it sounded best with an npn ge, REVERSE beta'd. figure that one out. but to my ear, that was the best fuzztone, and the best balance between clean (slightly boosted) and fuzz (seriously fuzzy!!) with the mix pot.

i also added a simple tone pot. i know, big muff or swtc, but i like the way this one sounds better, and it's bonehead simple. a pot and a cap. notice the input to the tone cct is to the wiper... this seemed to also sound better than with output from wiper.

any dang single OA will work fine... 741, 5534,tl061/71 were all tried.
also tried some fets and jfets. if you want a really killer tube like fuzz, try a j201 or similar!! the clean blend kinda sucks with them, but MAN!!
nice, i mean NICE distortion.

anyways... i really diggit... thanks gus once again for helping me out, and if you guys build this, please let me know..

stupid pedal trick will happen eventually. playing too damn much.

[jrod]

Very cool dude! Thanks for posting your layout and write up!

Can't wait to see your SPT video!

[Mark Hammer]

Ya know, Jimi, a diode placed after both C1 and C2 would get you an octaver with the clean/dirty balance adjusted just right.

[pinkjimiphoton]

thanks jrod....

mark... talk to me.... please... as if i was a little child.
from nodes to ground?
in series with the signal someplace? (it's already fairly gated sounding, but in a good way)
i tried adding a diode clipper to the feedback path of the 741...in parallel with the 22p/10m network... it had a cool distortion but lost most of the volume (maybe cuz i used 1n60's, they were just kinda handy).

at some setting, it already does octave downs... it's pretty sick, be great to add the option of switching in octaves.

also for mod ideas, maybe put an fx loop in the dry path, so ya could patch your favorite wah in?

i am really diggin' it.

shaky hands on the close up... the chip is some vintage 741 in a can, the transistor an npn ge from a heath or thomas electric organ a cool-ass forumite sent me a bag of... (brain death struck, will give proper props when i get a chance to look... no brain, no brain!!)

some really poor quality pron. i have two gigs tomorrow and thursday (oyyyyyyyyyyyyy) so i don't think i'll be able to do video til fridayish.





tone control would probably be better if it had a buffer stage or something. at some settings it's much more pronounced than others, but i just wanted to take a little hair off of it.

but enough of my babble....

mark, please advise!!!

[pinkjimiphoton]

i was playing around with this thing, and boxed it tonite.
i noticed it was slightly below unity gain. bugger. so i modded it a little.

made r6 47k instead of 100k and reduced r12 from 56k to 10k.

that got it above unity.

but the "clean blend" part was kinda wimpy. got a lot of loss between full clean and full fuzz, and the clean was a good 4-6db quieter. fugger.

so i broke the rail at i12 and i15 and spliced in a really simple little boost circuit...point to point, flying above the rest of the stuff.

the output of c2, .1u now feeds a node of a 510k to b+ and 100k to ground connected to the base of the first npn i pulled out, a 10k resistor from collector to b+, and a 10k trimmer wired as a variable resistor from e to ground. output is a .047 chicklet from node of c and 10k back to the rail just before the diode clipper. litterally just spliced it in the easiest way i could.

NOW the "clean" is a bit of a boost, and can be trimmed with the volume, and about half way on the mix, you can hear the clean and the fuzz fairly well together.

i'm thinking a bit of a redesign is gonna come soon,with the second transistor added, it's an improvement, but not a giant one.

video soon, couple days. sick as a dog.

here's what i added... too lazy atm to redo everything...

[LucifersTrip]

from nodes to ground?

I believe this:
http://www.geofex.com/FX_images/grnrng.gif

i noticed it was slightly below unity gain. bugger

prob because you used bat47/1N60 instead of silicon as on schemtatic. did you try doubling em in series?

[pinkjimiphoton]

interesting, i wonder how it would work in this circuit. i could add some more stuff under the board i guess and try, but i can't see it being worth doing... maybe on the revised version i'm gonna try and work up.

it's not that it's too low in volume, really... when the fuzz is dimed and the volume is up, it's well above unity gain.
the "Dry" side of the mix was too quiet... not anymore. you get some phase cancellation i think as you blend from one signal to the next, or rather pan, i guess... it's quieter in the middle of the mix knob, but can be compensated for with the volume nicely.

could try doubling up the diodes, too, but i am really digging the tone as it sits. the octave thing tho is intriguing..

i gotta dumb question... the first transistor is wired up as an emitter follower being used as a buffer, right?
at least for the clean signal....

so my question is, should i ditch the .1u cap coming off the e of q1 and feed the base of the added transistor directly, i mean not with a coupling capacitor? it seems to lose some balls from what i'd expect with two transistors.. ideally i'd still like it just a smidge louder, but right now you can get a pretty sweet blend of dirty and clean. if ditching that cap will improve the circuit, i'm willing to give it a shot. or maybe add in a real small cap in parallel, like on the regulus fuzz? turn it from a full range boost to a treble boost?

dave, you gotta try this one. it's a cool fuzz, and it can get them ripping velcro shreds of human flesh on acid 60's biker exploitation fuzz sound i know you'll appreciate.

[Gus]

A basic schematic of an adjusted circuit using opamps
the dual jfet opamp is a buffer PI
the schematic is missing parts and power connections
posted as a starting point
Note the change to the fuzz, mix and volume values
Not posted as a "better" but as a different adjustment

[pinkjimiphoton]

looks good gus...
hey... think we could do this with like a quad inverter like a 4069?
thinking could use the last unused part for a tone control like i did on the boogie snake thing i made a few months back.

be cool to do it all on one chip!!

[pinkjimiphoton]

after revisiting this thru my twin for a while, it's totally obvious the clean mix part is a waste of time... the fuzz and clean are i believe out of phase with each other, at either extreme of the pot, you have a loud clean (to the left) or a loud fuzz (to the right) but anywhere in between it loses most of it's balls.

the fuzz alone sounds great. the clean blend isn't worth it imho

[Gus]

So remove the stuff to the left of the - input as a starting point

Use a emitter follower with a 10K in series after it to the inverting input

[pinkjimiphoton]

gus bro, can you explain that a little more? which schematic are you talking about the original one, or your revisited one?