Of Fuzzes, Opamps and Buffers...

[Max]

I have a Hendrix Fuzz Face breadboarded that works fine (with an additional mod, but this will come later) and I was thinking about adding a dry/wet option, so I took the Madbox circuit from THCustom and put the fuzz on one channel while the other send is connected directly to the return to get the dry signal.
Result, the dry signal works perfectly, the fuzz is nowhere to be heard, maybe just a tad.
Now, I know that fuzz circuits don't like too much opamps (or anything else in front of them), so what would you guys suggest, maybe a little jfet buffer between the input opamp and the fuzz might do the trick?

[WormBoy]

Result, the dry signal works perfectly, the fuzz is nowhere to be heard, maybe just a tad.
Now, I know that fuzz circuits don't like too much opamps (or anything else in front of them), so what would you guys suggest, maybe a little jfet buffer between the input opamp and the fuzz might do the trick?

Fuzz face after a buffer will be harsh with a lot of nasty highs. If the fuzz is 'nowhere to be heard' it sounds like you need to debug something. There are some tricks to get a fuzz to play nice after a buffer (i.e., make it sound more like it does as first in the chain): add some series resistance at the input (e.g., a 100k pot so you can tweak to taste; see Fulltone 69 fuzz), or use a small transformer (see http://www.muzique.com/lab/pickups.htm). Compare the sound (and the interaction with your playing and volume knob on the guitar) between the various methods, and with the fuzz first in chain, and see what you like best.

[Max]

Thanks, yes I know there might be something to debug, but the breadboarding is such a mess that I thought "I'll look into it but not now".
First thing first I'll try the input resistor, If I manage to adjust the impedance with that it's much easier (and has to fit in a 1590A  ).

[juansolo]

A lot of old fuzzes just don't work right with a buffer between it and the guitar (a wah will likely screw things up also). They rely on the guitar to essentially be part of the circuit to do their thing. To avoid these problems you need to look at muff derived fuzzes or something more 'modern'.

[Max]

Yep, I'm starting to realise that...
This Jimi Hendrix fuzz is a bit more refined version (if I can use this word for a fuzz) of the fuzz section of the Vox Double Sound, where the fuzz was in parallel with the wah. Well, I tried to put this circuit in parallel with the same Vox wah and it just doesn't work, sounds awful, while in front of the wah works great.
Well, if I don't make it work I'll maybe build it without the wet/dry control and maybe look into something different like some muff or similar.

[somnif]

Build a "pickup simiulator" and stick it in front of the fuzz, then you can put it anywhere in the chain.

http://www.muzique.com/lab/pickups.htm



Any cheap, small transformer (including any cheapy old pickup you may have laying around), a trim pot for adjustment, a tiny cap to ground, and off you trot. Now your fuzz gets that nice magnetic loadup that it appreciates, regardless of where it is in the chain.

Note that I do recommend putting a buffer AFTER the fuzz if you use one. There can be a little high end attenuation with these in some cases, that a buffer can help buff out.

[jubal81]

IMO, any fuzz that won't work after a buffer is just a poorly designed circuit. Like Juan said, look to the muff family or if you like the FF topology, look to Skreddy circuits like screwdriver and lunar module.

[Max]

Yep, I'm gonna have a look at some other circuit. I was looking at the FF just because I had all the components at hand, but then I started thinking I could change this or modify that and then I just can't stop

[Muadzin]

IMO, any fuzz that won't work after a buffer is just a poorly designed circuit. Like Juan said, look to the muff family or if you like the FF topology, look to Skreddy circuits like screwdriver and lunar module.

I fully agree. We no longer live in the 1960's when men had barely set foot on the moon. It's 2019. We can build probes that can visit worlds in deep space. Surely we can build a fuzz that plays nice with buffers and acts like it should act behind a buffer. To not do so is lazy design.

[midwayfair]

IMO, any fuzz that won't work after a buffer is just a poorly designed circuit. Like Juan said, look to the muff family or if you like the FF topology, look to Skreddy circuits like screwdriver and lunar module.

I think a Fuzz Face sounds better after a buffer. It doesn't break the damn fuzz, it just sounds different.

[somnif]

IMO, any fuzz that won't work after a buffer is just a poorly designed circuit. Like Juan said, look to the muff family or if you like the FF topology, look to Skreddy circuits like screwdriver and lunar module.

I think a Fuzz Face sounds better after a buffer. It doesn't break the damn fuzz, it just sounds different.

Its funny, I have 2 FF's (both silicon). One sounds fine anywhere in the chain, the other sounds gated and ugly (which may have its uses but I'm not fond of it). My only germanium fuzz (a 'factory clone) is rather fussy, but more about the guitar rather than the chain (it loves my LP, doesn't like my tele).

In other words, in my experience, old school fuzzes are voodoo. If you're worried, shake a bottle of rum over them and offer them gifts of small trinkets and chicken bones occasionally.

[Max]

Yes, for (the very little) that I've seen this is the case. Ages ago, around 1996 I made a part-for-part copy for a friend of mine of the fuzz circuit from the Vox Double Sound Fuzz-Wah and it sounded just like the original. I also put it in a box with a fix wah made using a cry-baby. Now, I wanted to build another one, because it was really a handful of components, a very basic silicon fuzz face, but I couldn't find the original transistors, I think they were BC238B. When I finally managed to find them I discovered that the circuit sounded completely different, absolutely not as aggressive as the original. But being a relatively simple circuit I was toying with the idea of modifying it a bit, first adding some components to change it into a JH Fuzz Face. I also swapped the BJTs with MPSA18 and the sound is much, much better, now. I added a 3PDT switch to change some components and move the frequency response down to use it with a bass, but the change is not really obvious, I should do some recording to have an actual comparison.
However, it's a one-sound circuit, but at this point I think it's easier to divert to some more refined (and already available) circuit like the DSOTM.

[Max]

Fuzz face after a buffer will be harsh with a lot of nasty highs. If the fuzz is 'nowhere to be heard' it sounds like you need to debug something. There are some tricks to get a fuzz to play nice after a buffer (i.e., make it sound more like it does as first in the chain): add some series resistance at the input (e.g., a 100k pot so you can tweak to taste; see Fulltone 69 fuzz), or use a small transformer (see http://www.muzique.com/lab/pickups.htm). Compare the sound (and the interaction with your playing and volume knob on the guitar) between the various methods, and with the fuzz first in chain, and see what you like best.

I manage to inspect the breadboarding and one of the circuits I used had a faulty trace. Fixed that and added a pot in series to the fuzz to adjust the impedance and it works, I can mix the wet and dry signal, and get a decent fuzz sound, but it's not really usable, it would require a lot of tinkering and I've already ordered the parts to build the DSOTM  , so I'm not going to waste any more time on this, I just wanted to put an end to this topic 
Thanks for all the answers!