Ross comp has a hint of tremolo sound to it???

[rosssurf]

I have built the Ross comp from GGG making sure to not the corrections of the caps that were incorrect. It works as it should but there is a faint wavey tremolo kind of sound. I assume this is from the two halves feeding Q's 3 & 4 being missmatched. I used Q's with very close hfe's as well as matching my diodes and using 1% metal resisitors. I do not have the ability to check capacitance, I wonder if my caps are off. I believe they are 20% +/- brownish orange in color.
Here is the layout  http://generalguitargadgets.com/diagrams/geo_d&r_comp.pdf
Any thoughts? 

[rosssurf]

Bump?    ...? help!

[Jay Doyle]

Well...

I think we need some more information. When does this occur? At what portion of the note? What are the settings when this happens?

What you are describing is normally due to ripple in the rectifier circuit, but the 10uF cap integrates the Ross rectifier circuit so that there isn't any ripple. What is causing this is a changing of the voltage on that 10uF cap.

The only thing that I can think of is that the transistor after the 10uF cap that feeds the sustain pot is leaky which would drain a little of the voltage off of the cap, only to be charged up again by the signal from the rectifier. This would cause the gain of the 3080 to fluctuate with that changing voltage on the 10uF cap.

Try a new transistor in that position and see if that helps.

I guess it could also be some sort of stray capacitance on the Iabc port of the 3080 chip, maybe try swapping out chips too?

But I do have to admit that this one has me a bit stumped.

[rosssurf]

Swapped out the 3080, no change. It seems the last Q must have been leaking. I replaced it with a 5089 . Seems good now. 
Thanks

[Jay Doyle]

Swapped out the 3080, no change. It seems the last Q must have been leaking. I replaced it with a 5089 . Seems good now. 
Thanks

Great! I do have to say that this is probably the first time I've figured an odd thing out like this on my first try.

Glad you got it working.

Jay Doyle

[rosssurf]

Very good! thanks for your help