Mayer Mods -- I did 'em and now have some questions...

[mordechai]

I did the Mayer Mod switch, or something very close to it, on my FF...470R to 1K, 1K fuzz pot to 2K fuzz pot, and the 8.2K to a 25K pot. 

The thing has more volume as expected, and I THINK the increased 2K fuzz pot is giving it a touch more gain...correct?

I am guessing that the switch to a higher value q2 bias resistor (I usually set the 25K trimpot to about 15-18K) compensates for the increased fuzz pot value where an 8.2K resistor would not allow for a decent bias...am I right?  I initially tried just subbing in a 2K fuzz pot without changing the Q2 bias resistor and except for the very final bit of the pot's sweep, there was no fuzz to be had.  Does the higher value collector resistor provide a more usable sweep?

Finally -- when the volume on my guitar is maxed the circuit sounds great, but when I back off the volume, it doesn't clean up as well as the standard Fuzz Face circuit does (1k fuzz pot, 8.2K bias resistor).  Is this to be expected and inherent to the character of the "more gain" modification itself?

[Mark Hammer]

The use of a 2k Gain pot will allow one to achieve lower gain, which can be handy, but not higher gain.  Remember that max gain occurs when there is a direct path to ground for the emitter through the electrolytic cap.  Hard to go lower than zero ohms, and a 1k pot is entirely capable of doing that, as is a 2k, 5k, 10k, etc.

[mordechai]

Ah, so that's why, with the standard 8.2K bias resistor, the pot very quickly reduced the fuzz with a small turn...but with the upped bias resistor, wouldn't the compensation equalize so that it doesn't actually get lower gain than a 1K with the standard bias resistor on Q2?

[Mark Hammer]

How much fuzz you get with a given pot position is pretty much a byproduct of pot taper.  In some respects, a reverse log is what one wants for such a gain pot; one that skips through the higher resistance vales pretty quickly, and then eases gently through the lowest resistances, where smaller differences in resistance make for greater changes in distortion.