Negative Ground Fuzz Face problem

[atzeehh]

Hello,

I have a question about a vero schematic.
Is this schematic working? Or verified? does anyone know or build one?
I built this yesterday (just starting with this hobby)
And ive followed the schematic but if i plug it in the bypass works perfectly.
But when i stomp it, it gives me a volume drop and you can hear the guitar with al little bit of fuzz in the low end, but not that much. And volume/attack doesnt do anything actually.

Thanks for your time.

Atze

[holm]

Hey
I build this some time ago, but have put it aside 'cause it was a bit flimsy soundwise. I'll have a look at it tonight.

[GrooveChampion]

Images of your build would be really helpful.

[atzeehh]

Okay, so i managed to get it working (flip the transistors). But now i have some kind of low hum and a high hiss. When i turn down the volume control a little bit the low hum goes away but the high hiss stays.
When i turn down the volume/tone all the way, the hiss raises and is very loud. I searched google but no one has this. What should i do? Thanks for helping.

[atzeehh]

here are the pics

[GrooveChampion]

Are you using single coil pickups? It could be natural to the pedal, it also could be a low quality power supply or a grounding issue in your house.

[holm]

I plugged mine in last night, and I get the same result as you described initially. Dunno what's wrong with my build. I got hold of a bunch of germanium NPN's (AC186, AC 176 and AC141K) from ebay, and they are cheap and sounds great, I would do that as well if I was you, then are able the use negative ground power supply.

[GrooveChampion]

Could always be that the layout aint good. But from what I see check carefully for bridges between the vero strips and isolate everything as much as possible.

[atzeehh]

Yeah i used single coils and humbuckers, I used the power supply with my other pedals but also no luck, and i also tried grounding

[atzeehh]

It actually sounds really good with the 470pf and 2N3906. I hope anyone knows how to fix this problem. Because when its fixed  you have a great fuzz, with good sustain.

[atzeehh]

I send the creator of this schematic a message, so if i know anything i will post it here for people that want to build this.

[atzeehh]

Credits to Joe Doc Music,

I contacted Joe and this are his replies:

Naturally, the 2N3906 is a PNP transistor, which could be easily subtituted for a 2N3904, the very inexpensive NPN counterpart. The 2N3906 is very high gain, which in this case, adjusting a low gain Germanium circuit - may lead to more noise due to the very high gain Silicon transistor.
One easy fix for a hissy sound or interference when the cable is connected and guitar volume all the way up is to add a low value resistor in series with the input. 470 Ohms or so is fine.
Hope that helps,

and...

It's a clean build, so I recommend trying a few things to see what might be the cause of hiss. My guess is the extreme gain of the 2N3906 as compared to any germanium...
But you may want to build a test probe - just get a jack, ground the sleeve, then attach a lead to thip via a 100nF capacitor, and you can touch parts of the circuit while strumming the open strings on your guitar to see where the noise may be coming!

I didnt have time to try those tricks, but i will do that this week, i hope it helps.
In the meantime anyone who has tips and tricks is welcome.

Thanks

[atzeehh]

This is from the original creator: Jack Orman.
Could this be the solution?


I received an email asking if this method of powering could cause oscillation in the circuit. There is always the possibility of oscillation in all high gain circuits if good construction practices are not followed; however, there are many examples in circuit history of PNP transistors operated off a positive supply. Most of the time when you see an NPN driving a PNP in a typical transistor circuit the PNP is operating from the positive supply. The Roger Mayer Axis Fuzz is but one commercial example of this technique; the Harmonic Percolator is another.

If for some reason oscillation does occur, a quality low esr capacitor from the positive supply to ground will solve the problem everytime since it effectively places the power rails at the same ac potential. Put the capacitor on the pc board if possible. Also keep the positive and negative power wires as short as practical. I've used this method with two different fuzzface derivatives for years with no problems and one of them has a quite long positive power supply wire.

The circuit can easily be converted back to positive ground if you get oscillations that are not cured by the power supply filter.