Roger Mayer Fuzz Face too quiet?

[carboncomp]

Iv just built a Roger Mayer mod fuzz face, and I'm only getting just over unity with max volume and fuzz dialed in?

Replaced the 470 with 1K
Replaced the 8.2K with 18K
Replaced the 1K fuzz pot with 2K.

Anyway to get a little more output?

[Seljer]

Increasing the 470/1K even more will give you more volume but you may need to balance it out with the 8.2k/18k to retain the same bias voltage.

[davidallancole]

If you look at the Vox Tonebender on the following page, you'll notice that they used a 2.2k resistor in the 470 ohm slot.  The think to watch for as Seljer mentioned is to adjust the bias afterwards.

http://www.geofex.com/article_folders/fuzzface/fffram.htm

[carboncomp]

Thanks!

What voltages should I be aiming for?

[peterg]

Q2 collector should be 4.5. You may need to reduce the 18k resistor.

[carboncomp]

Q2 collector should be 4.5. You may need to reduce the 18k resistor.

That worrying, I'm getting 7.4V when muted and down to 5.8V when playing on a new battery (9.8V)......which do I take as my bias measurement?

Have 2.2k (470R) and 18K (8.2K).

[peterg]

Can you post a schematic and show the mods you made? Are you using pnp or npn transistors?

[duck_arse]

always measure your bias (and other static voltages) without an input signal. input short to ground is good, to.

[carboncomp]

Can you post a schematic and show the mods you made? Are you using pnp or npn transistors?

Using this schematic


I'v bread boarded a couple more Fuzz Faces up with this Roger Mayer layout with different transistors/Hfe ranges and all have much higher Q2 Collectors Voltages than 4.5v.

Is a higher Q2 Collector voltage just one of the characteristics of this mod?

[bool]

if you want to reduce the q2 col. voltage, the easy way is to reduce the pot. value. but this isn't practical.

the other easy way to experiment would be to put some resistance in parallel to the pot., iow. shunt it (the resulting q2 emitter to ground resistance) with a resistor or a trimmer somewhere around 3-5k and see what happens.

or try something unrully, unethical and radical - replace the trannies with BC212 silicon, forget jimi and mayer.

[duck_arse]

and are you doing sillicon or germanium?

[carboncomp]

and are you doing sillicon or germanium?

Germanium, modern NKT275.

I can change all the values around all day long and get a Q2 Collector voltage of 4.5v, but then its not a Roger Mayer Fuzz Face, so did Roger Mayer Fuzz Faces just have a high collector voltage??

I don't get how this Mod would have as low voltage as 4.5v with these values