Fuzz face squealing

[burnt fingers]

I just finished a fuzz face tonight which is basically the Axis face from Fuzz central minus the smoothe pot.  I put A 33k resistor there because that's where I liked the sound and didn't need the pot. 
I boxed it all up and it sounds great escept that there is some horrible squealing when I turn the volume past the halfway point with the fuzz about 3/4 and up.
I tried a .001 cao from the input to ground so I don't think it is coming through the input.  I have a .001 cap along with the 100k resistor off the base of Q1 to Q2.  That smoothed the sound out but the squeal is still there.  I am using 2n5089 in both slots but even with other tranny's the squeal lives on.

I have a 100ohm resistor in series with the power as well as the 100uf cap from V+ to ground.

Any ideas as to where this noise may be coming from and how to fix it.

Thanks in advance.

Scott

[pyrop]

Hi
I had the same problem with my first build which was a fuzz face. Anyway the problem ended up being my volume pot wiring. I had the ground wire going to power supply & not to ground.
So first up I'd double check the layout, polarities of the caps & off board wiring.
Then I would use an audio probe on the collectors of Q1 & Q2.
Did you check the gains of the transistor you used? Use the lower gain tranny in Q1.
It just a matter of systematically checking each trace & component.
Hope that helps
Generally 2n5089's have a bit to much gain to use in a fuzz face so maybe try some low gain tranny's.

pyrop

[brett]

Hi.
2 x 2N5089s are likely to lead to lots of problems.
You could tame Q1 with a resistor (about 220 to 330 ohms) between the emitter and ground , but that will affect the tone somewhat.

I have a cable that sometimes makes a poor earth connection.  This results in a squeal that changes pitch as I put my foot near the box (presumably due to capacitive effects).
good luck

[Paul Perry (Frostwave)]

Yes, it's probably a matter of feedback between various unsheilded wires. A dead giveaway, is when something works "until it is put in the box". Yeah, it's happened to me too. Very annoying.

[burnt fingers]

Hey guys,

I tweaked this a little more shoring up some solder joints and so forth.  It still squeals when I crank the volume and the gain but I also realized that I had my amp reeeaalllly low cuz I was working on this late last night.  Anyhow, witht the volume at about 50% the effect is plenty more than unity. at that point with the gain all the way up there is some white noise ( to be expected) but no squealing.  I think I will call this a success.  I don't need the volume any higher than 50% and the gain will probably only be about 3/4 up. 

Thanks for the responses.  On to the next project.

Scott

[nightingale]

Hi,
Lower gain transistors will help for sure.
It's a shame.  I love the sound of Si fuzz faces cranked. It is hard to get them not to squeal, or have really high pitched feedback without having a super sheilded enclosure like the RM rocket series, or those giant dunlop ones.

hope this helps,
ry

[phaeton]

are all your wires only as long as they need be?

I just fixed the squealing in my high-gain pedal by going through and tediously shortening every single wire coming off the board.  Took me an hour or so to do, but it fixed it up.

[burnt fingers]

I havn't shortened the wires.  I may go back and do that just for piece of mind but otherwise it is working sufficianly.  The Squealing is now only when the gain is dimed and the volume is past  50-60%  At 50% it is well above unity( this thing is loud ) and if I backed the gain down some more I could increase the volume.  I know lower gain trannys would help.  I have a 2n5088 in Q1 and 2N5089 in Q2 because I want an over the top fuzz sound.  I wanted this thing to be in you face and boy is it.

Thanks for all the suggestions.

Scott