Compressor circuit debug

[jake fegely]

I just finished my 2nd build, which is the Ross/Dyna compressor from the tonepad site. Initially I built it to the Ross specs, but didn't like the loss of high end so I changed it to the Dyna specs, which I like better.  It's producing some nice sounds with 2 problems that I can't figure out.  The main problem is an over-emphasis of the initial pick attack - almost like a clicking sound at the very beginning of a picked note.  The second problem is I'm getting a popping noise when switching the compressor back on after it has been off.  I presume this to be true bypass pop, but there is 2.2M resistor at the input of the circuit, prior to the first cap, which should prevent that (the schem called for 4.7M, but I substituted).

It's built per the tonepad schematic to include the RG Keen mods, which are part of the pcb.  Further, I added 2 mods from Mark Hammer as explained on fuzzcentral - a .001uf cap in parallel with the 10K output resistor, and the variable recovery mod which replaces a 150K resistor with 3 resistors and an on-off-on switch.

I suspect the problem is related to 3 of the transistors as the voltages below show that Q1, Q2 and Q5 do not have a high enough base voltage relative to emitter voltage.  However, I have been unable to identify any problem. I have checked every resistor and they all seem to be fine.

Something else that seems odd is that I hear very little (if any) difference while adjusting the trimpot (while playing the guitar through the pedal).  The entire range of adjustment on the trimpot sounds almost identical.  I did measure varying resistance in the trimmer as I adjusted it.

The voltages below were taken while the pedal was powered by a one-spot, the trimpot was at 10 o'clock, the SPDT switch was at 160K and the sustain control was fully counter-clockwise.

Chip - Pin
1   not used
2   3.99
3   4.10
4   0
5   .68
6   2.87
7   10.12
8   not used

Q1
C   10.56
B   1.60
E   2.32

Q2
C   7.68
B   2.97
E   2.78

Q3
C   9.04
B   0
E   0

Q4
C   9.01
B   0
E   0


Q5
C   10.39
B   8.95
E   9.76

D1
A   0
K   8.92

D2
A   0
K   0

D3
A   0
K   0

The diode measurements were taken with the 1-spot plugged into an extension, while the rest of the measurements were taken with the 1-spot plugged directly into the wall outlet.  Through the extension, the voltage at the 9V input was 8.92.

Any ideas would be greatly appreciated,

Thanks,
Jake

[pedalgrinder]

ok one of your problems i can sort out. the popping if your using 3pdt just seems to click no matter what trick you try you can certainly quiet them down to a degree but i in the end had to start using the millenium bypass rather than just a 3pdt. the led seems to put some sort of click back to earth especially if you like your led bright like i do. the other way of doing it is the same as the ibanez's pedals with 2 fets some say oh not true bypass but it's really not that bad just depends how anal you are.