Roger Mayer Axis Fuzz - Changing the overall tone?

[Mr McRuff]

Hi everyone! I'm hoping you may be able to offer some tips on where in the Axis Fuzz I can modify the circuit to get more bass response. I've pretty much build the pedal with schematics found online and included some of the mods found at this forum.

I like the pedal a lot and found each mod to be useful in the overall performance of the pedal. But the one thing I've always noticed about it, is that it tends to boost the upper frequencies and can be awful bright for my taste. I did try changing the output/input cap values, but never wound up with the sound I wanted in the end.

The one cap I haven't experimented with is the 0.1uf on the drive control, since I'm really not too sure what its function is. Can anyone tell me what its purpose is? Does it simply shunt a certain frequency range to ground at that point? If I play around with this caps value would I get some more bass end response? And which way to I have to tweak - higher or lower?

Thanks for any help!

[patrick398]

What input and output caps did you opt for? A bigger input cap will allow more bass frequencies through to the gain section. A lot of distortions / overdrives limit the bass to avoid it sounding flabby, you may like it, you may not.

The cap bypassing the gain pot will have a big effect on the tone, you might need to experiment to see what value you like. I think altering it's value may also affect the gain.

As i understand it the cap allows frequencies of a certain range straight through to ground, rather than through the gain pots resistance.

Stick around, someone who actually knows what they're talking about will be here in a minute 

[idy]

I have found I like a treble cut control and have done it by monkeying with the 1n cap and 220ohm resistor to ground on the base of Q2. I replaced with a 66n cap and a 50k pot. the main thing for more bass would be the input cap ....and maybe the bypass on the gain control.

[Mr McRuff]

Thanks patrick398 & idy! I feel like I'm off to a good start getting some input from you.

For the input I opted for a 1.0uf (105M) monolythic capacitor. On the output I went with 4.7uf 50v electrolytic cap.

idy - for the part of the circuit you are referring to, I use the same value cap as posted in most schematics I saw (.001uf), but replaced the 220 ohm with a 220k that I saw mentioned in another post. It actually made a nice difference with how the pedal responded. I also modded the 47k resistor, which is connected into the electrolytic feeding into the drive control with a 27k & trimmer pot. I find it helped control the distortion produced - I really like the gain aspect of this pedal more than the fuzz, this allowed me to change the sound if needed for different recordings. All resistors used on the board are carbon film. Caps are Sprague & other well made name brands.

Right now I have it housed in a run of the mill Radio Shack enclosure, just to keep the board from getting damaged. I could add a photo if you guys think that would help. The board is nothing special, just perf-board (0.1 x 0.1 spacing) and point-to-point style wiring - no fancy board.