Desolation of Oscillation

[u1061810]

Hi All,
  I recently built a PNP negative groud version of a Fuzz Face from G.G.G. and I like the sound of it , but it gets serious oscillation and noise when the fuzz pot is maxed out.What are some of the sollutions to this problem?Thanks for any help regarding this issue.

[petemoore]

The easiest way is turn the gain pot or your guiltar volume pot down.
 Or alternatively you can put a resistor across it's ears to set a reduced max gain setting.
 Using lower gain transistors [for Q1 really helps clean things up], piggybacking is my prefferred method for adjusting Q1 gain to my ears liking, [Q2 too but finding Hfe Gains of 100 or 150 ins't a problem, piggybacking lets you try different transistors and adjust the gain]  This also helps to get well defined notes, there seems to be a trade off in FF's between the ability to get high gain tones Vs. noise, oscillations or hard to controlness, the tradeoff curve can be bent, but only so far...that's when you throw a 1Q Booster on the front end and call it a 'Fuzzbender'...because a Tonebender is a FF with a third transistor.
  Rolloff caps between ground and a collector are quite effective in altering gain, frequency response, volume and generaly playing characteristics, they will roll off highs. Also between Base and collector is a good place to try small caps [.00XXuf caps like .0022uf or a little bigger for starters]. Bigger caps in these places reduce treble.

[RDV]

It may also mean that you used a higher gain @ Q1 than @ Q2. If you have them socketed, switch them & try it again.

RDV

[gez]

Try sticking a large value cap across the rails.