Wah Wah Debug

[kurtlives]

First of all its not so bad its working but has one small problem. It can't reach unity gain. I have tried playing with the input resistor to no avail.

I am using this schem http://www.generalguitargadgets.com/diagrams/wah_847_sc.gif.

R1 is 10K right now
R4 is 330R
R7 is 68K

I am using BC109C transistors with 500 hFE.

Battery 8.68V

Q1
C 5.74V
B 0.98V
E 0.38V

Q2
C 8.29V
B 5.14V
E 5.22v

I am lost...so simple yet I cant find my problem. Seems like it lies at Q2 but I am lost.

Help me  .....Thanks

[GibsonGM]

Check around R5 and R7 for bad connections/solder bridges, maybe?  Transistor pinouts ok?  Weird problem.

[kurtlives]

PCB is super clean and there are no solder bridges or shorts...

Transistors are in correctly....soldered in. I was swapping in transistors when I was building for different sounds. I decided on the BC109C's then soldered em in. Then I think I noticed the problem then...Guess I should try new transistors.

[kurtlives]

No one?

[ayayay!]

What did you use for R4?  Q1's B & E seem too low.  Try another one. 

[kurtlives]

R4 is 330R.

[mdaudet]

I suggest you to add an extra circuit at the output of the wah (lug 1 on pot). Add a " fet buffer" with internal trim to adjust the overall gain in order to reach the unity gain.

Try the last buffer on the circuit that appears on  Francisco Peña's "Wah Wah buffered" at tonepad. Use MPF102 to avoid saturation.

http://tonepad.com/project.asp?id=29

I have done this mod before, it works great.

cheers.

[kurtlives]

Thanks....but even with the input resistors jumpered I cant reach unity gain. 

This bothers me....Is this how all TB non buffered wahs are?