poindexter overly gated sound

[krankor]

Hi! This is my first post to this forum.

I just finished making the poindexter pedal and it's working except that the signal is overly gated. The guitar volume has to be all the way up and if you back of even a little the signal just gets gated. I used 1n34a diodes and 2n4401's for the transistors. Really hoping  no one's gonna say that the 4401's are the problem hehe!

I checked all the resistor values and they are correct. I did substitute a 47pf cap for the 10pf cap cuz that's what i had. so i put 2 18pf caps in series and swapped them and it didn't seem to make a difference.  Any thoughts would be appreciated!

[nzCdog]

What kind of voltage are you getting at Q1 collector?  You could try reducing r4 to 8k2 or 6k8 and see how that goes

[krankor]

Thanks for the reply! Tried going down to 6.8k on R4 and the voltage on the collector of Q1 is now about 7V, but I haven't noticed much change in the gating. hmm. would you be able to point me to a link that has some discussion of how this effect works?

looks like there are a few more amplifier stages where i might try lowering the resistance on the Q collector?

Thanks for the help!

[nzCdog]

Change R4 back to 10k.... Reduce R2 to 82k, then test... if no good try 68k
Hopefully that will help

[nzCdog]

Basically if a transistor is gating, it can be related to insufficient bias causing it to fall out of conduction... Normally the subsequent stages will be propped up by the first stage's output...  So hopefully raising the gate base bias of Q1 will solve your problem

[krankor]

Cool, will try it. Gee, I actually learned something!

[midwayfair]

Before you go tearing up your circuit board, though, check that your transistor(s) aren't backward. A silicon bipolar transistor circuit should not require extensive biasing except to fine tune the sound. 7v is waayyy more than enough to get noise.

[krankor]

Good advice thanks had already done that cuz I've learned the hard way hehe. But it turned out that changing the bias on Q1 helped alot. Thanks for all the help!