The TOFUzz - octave down fuzz with minimal parts!

[Freppo]

Hi there folks

I have a new simple little circuit that I call "The TOFUzz"   
It's a fuzz that creates very synthy pseudo octave down sounds on certain frets

Soundclip, PCB and vero layout at my blog:
www.parasitstudio.se

Schematic


I hope you dig it.
cheers
/ Fredrik

[~arph]

That sounded amazingly good!  You say certain frets. How we'll does it track the lower notes? Octave jumping around? And how is the sustain? I think I'll mess around with it a bit too

[Freppo]

Thanks!

It doesn't track at all on lower noted basically, but there is a pretty wide area of tracking.
When it tracks it's mostly stable with little octave jumping, at least when using the neck pickup.
It has a very short sustain, but i'm working on a deluxe version to improve on these issues.
Overall I'm very happy how this version turned out considering the small partscount.

/ Freppo

[~arph]

I'd step it up to a LM324 so you have four opamps. Yeah its the small parts count that makes it so nice..

[bool]

OK, so we're waiting for the roasted tofu-zz version.

(I think that something simple, like a band-limited clipping stage cca 80-300Hz and an adjustable sallen-key lowpass, all within a single lm324 will get you near "there", pretty close)

[anotherjim]

Oh you're at it again! That does sound good.
I have a guitar "synth" on my breadboard at the moment. One thing I found with the "squarer" - using an opamp comparator, is it jitters badly on the decay tail. I found giving it some hysteresis with a positive feedback reduces the jitter without noticeably reducing the sustain.
So long as you don't mind using neck p/u with tone rolled off, you don't need too much pre-filter to reduce mis-tracking on harmonics.
-

[bool]

@anotherjim

Modding the tofuzz' IC1A into a schmitt trigger-y type of a circuit would require only adding a single resistor, inline with the 10K pulldown that's already in the schematic, and connecting the "+" input to the both resistors' junction.

I'd start with 100 ohm and go from there ... should be easy.

[~arph]

@anotherjim

Modding the tofuzz' IC1A into a schmitt trigger-y type of a circuit would require only adding a single resistor, inline with the 10K pulldown that's already in the schematic, and connecting the "+" input to the both resistors' junction.

I'd start with 100 ohm and go from there ... should be easy.

Shouldn't there be a resistor to in the vref path of the + input then too?

[bool]

Oh, I apologize. I overlooked that. I thought that the input was biased to gnd. I guess I was wrong. So yeah, the same recipe but this time probably better done with a 100K feedback (so to not load the Vref divider) resistor into a 1K (perhaps a pot?) to the Vref. Same basic shmitt circuit.

Does it improve or get worse?

[Freppo]

I have a guitar "synth" on my breadboard at the moment. One thing I found with the "squarer" - using an opamp comparator, is it jitters badly on the decay tail. I found giving it some hysteresis with a positive feedback reduces the jitter without noticeably reducing the sustain.

Nice idea. I'll try that! Also very curious about your guitar "synth"..

[anotherjim]

Yes, it is a Schmidt trigger (hate writing that as I can never remember how to spell it) , but I'm going into the + input via 10k series  and 1meg feedback to + input. - input is Vref. I do have quite a lot of pre-gain before that.

Synth is being cut down at the moment - I've found a pretty good bowed string simulation, so I'll present just that fairly soon I hope.

[Crontox102098]

How it sound with chords?

[~arph]

Yes, it is a Schmidt trigger (hate writing that as I can never remember how to spell it) , but I'm going into the + input via 10k series  and 1meg feedback to + input. - input is Vref. I do have quite a lot of pre-gain before that.

Synth is being cut down at the moment - I've found a pretty good bowed string simulation, so I'll present just that fairly soon I hope.

Schmitt

[helloesposito]

DELICIOUS. Sounds like a much better Blue Box.

[Bishop Vogue]

Just built this with your vero and it didn't work

I used an LM358N. do you think that might be the problem?  Has anyone verified the vero?

[Bishop Vogue]

what the eff? now it works!  must have been a short.  Yahoo... it sounds great!