weener advice: is this normal?

[the3secondrule]

just after a bit of advice, really...

I've built my weener as follows:

c1: 10n
c5: 15n
omitted c6 and freq,
and used 2n2925's from Timbo in Q1 + Q2
whipple inductor

and everything else, is as per the build docs.

I've noticed when I sweep the wah slowly, there is a point about half way through its travel where there is kind of a peaked, ugly distortion. Doesn't seem to matter where i set the peak pot.
it's more noticeable on the lower strings.

wondering if
A) this is some issue with the transistor gains
B) the jfet buffer is clipping
or C) that's how it is supposed to sound. never noticed anything like it on other Crybaby's and Vox's i've modded though.

thoughts?

[JakeFuzz]

What value are you using for the emitter resistor on Q1? That happens on mine too, pretty sure it is Q1 clipping. I could definitely see how that would be bad if you were using the wah clean a lot, but with dirt that extra grit and volume makes things sound awesome! Try raising the resistor and see if that helps.

[the3secondrule]

Ah, that would be it!

I though it had used a higher value (forgot to mention that) but i just checked and i've got a 390r in there.

I'll swap it out and see what happens. thanks man!

[the3secondrule]

hmmm, bumped the resistor up to 470r, and it moved the peaky distortion from the top of the sweep to the bottom, but it is even more noticeable. I like to use a lot of wah/delay on clean guitar, so i am keen to get this sounding sweeter.

I think i'll start swapping transistors at q1 and see what happens...

any other thoughts, anyone?

[madbean]

You should be able to get clean, non fizzy wah, so I think it may come down to the particular transistor used in Q1. Try going up to 560R and see if that fixes it without reducing the output too much.

[joegagan]

brian, i agree, also sometimes to clean things up i will go to an in input vol, 100k to ground, and/or smaller input cap. but the idea to try a lower gain trans in Q1 and/or higher value  r @ Q1 emmiter are good things to try first.

[the3secondrule]

ok, i've gone up to 560r off q1's emitter. the wah has just about cleaned up to a point that i'm happy with, but now the wah is losing volume when it is engaged.

any way I can increase the volume without increasing the gain going into the circuit?

[timbo_93631]

Lowering the value of R2 will get the volume balanced back out.  If you have 68k in the try 47k or 56k.

[the3secondrule]

Swapped in a 2n3565 with about 260hfe at q1, and its getting even cleaner.
i reckon i'll bump r2 down to 56k, and that should be it!

thanks everyone



J

[bangerang101]

I like using a 47k/10n combo for the input to boost volume and then make q1's emitter resistor (1k trimpot) variable if I need a little more or less bass/dirt.