Please help me saving this Wooly Mammoth

[::::FLARE::::]

Hi
this is my first post, even if I read this forum since long! As I have an problem I can't solve, here's my first question:
I built a wooly mammoth clone on stripboard. It works fine, tone is good, eq work wery well and all but there's a little issue:
if I put the wool knob to the max, and then slowly lower the pinch (reducing the gating effect) I get to a point where a loud pulse is heard and lowering the pinch even more makes the pulse frequency rise, until it becomes a kind of constant drone.
I double checked everything, and all seems ok. I dont know the voltage at the transistors pins in working unit, so if anybody knows it, please let me know.

Here's a sample of the phenomenon:
http://www.4shared.com/mp3/9nV_Skjd/wooly.html

If you listen to the sample, there's a digital background noise that comes from my poor audio card, and has noting to do with the mammoth.
Any ideas?

[::::FLARE::::]

so, I think I solved: the power supply I used to test the mammothe introduced a strong hum in the circuit, while it was obviously not noticeable with high pinch settings (max gate) as I lowered the pinch it produced that strange kind of feedback.  This is the only explanation I found, as I tested the circuit with a battery and it worked perfectly.
Just one thing : the  knob doesn't work in a very pleasant way: it dosn't cut the notes smoothly, but with a serie of "farty pops", I can't say it better. At the highest settings it produces no sound, it gates everything. You can hear it from the sample anyway.
Is it normal? it maybe depends on my low-output bass? I'll try the mammoth with my j-bass, that has higher output as soon as I can.

[crane]

Welcome to forum!
I would suggest you to do the testing with a buffer between bass guitar and the mammoth. This could change things a little and if it had a volume/boost option - even better. You could understand how it works with different signal levels.

[Ibanezsr500]

The Wooly Mammoth likes a high impedance signal fed into it, thats why it's not 'gating' the notes in a pleasent way. Try using a passive bass with it, that should solve your problem. If you want to use an active bass with the circuit, I suggest using this: http://www.muzique.com/lab/pickups.htm - It basically turns your low impedance signal (emitted from your active bass) into a high impecance signal (like what would be coming from a passive bass).

Have fun!