Dyna-comp/Ross mods?

[Mark Abbott]

I just dusted off my old Dyna-comp/Ross clone today. I couldn't but help think that the pedal does give the typical quish I heard many people talk of, but I'm looking for more sustain out of this pedal. I also really like way this pedal colours the sound of my guitars too.

Years ago I had an old four knob Boss compression pedal which sounded pretty ordinary, but it's redeeming feature was that it compressed my guitars signal in such a way that I was able to get much louder clean tones from my amp.

If I could get a bit of that happening in my clone, I'd be quite happy with it.

Yours Sincerely

Mark Abbott.

[Jay Doyle]

From reading your post I can suggest two things for you to get more sustain and higher output from the circuit.

For higher output, replace the 10k in series with the level pot with a jumper. This will give you a little less than 20% more output voltage available.

For more sustain, or a longer decay, you need to up the 150k resistor that is "shared" by the two transistors in the full wave rectifier. Try 220k and then 330k. You can also up the value of the 10uF cap but that is going to lengthen the attack time as well. I'd stick with raising that 150k resistor.

Try those simple changes out and let us know how it goes...

Jay Doyle

[Mark Abbott]

Dear Jay

Thanks for your reply. I can't remember if I tried replacing the 150K resistor with a higer value.

This is pretty much the history of that particular pedal. I originally used BC549's for the two transistors that are attached to the 150K resistor, the effect didn't work too good at all.

I had also been experimenting with Fuzz Faces and BMP's using BC549C's for some reason these pedals seemed to give more distortion with 2N3904's, so I tried putting these transistors in the compressor, the thing came to life giving me great sustain, almost distorted guitar type sustain. I was happy!

One day the thing stopped giving me as much sustain, I tried different 3080 IC's, I tried different transistors. I got back some of the compression, but not the sustain, not happy!

I'll give it go, and get back to you Jay. Again thanks for your help.

Yours Sincerely

Mark Abbott.

[Jay Doyle]

One day the thing stopped giving me as much sustain, I tried different 3080 IC's, I tried different transistors. I got back some of the compression, but not the sustain, not happy!

OK, this leads me to believe the 10uF cap attached to the 150k resistor, which is the integrating capacitor, has gone bad. It may be leaky. I would try switching this out.

It is a polarized cap, did you orient it correctly?