Ross Comp Mod Question

[ragtime8922]

The Carl Martin Compressor has an LED labeled "Busy" that lets you know when it is compressing and for how long. This would go great with the Mark Hammer Ross mod. You would actually see it working. Does anyone have a way to apply this to the Ross? I am out of town and can't work on it right now but I thought I'd share it.

[ragtime8922]

Bump (Where's Mark. Help me Mark, HELLLLLLLLP)  

[phillip]

Is the Carl Martin compressor a modified version of the Ross Compressor?  Looks quite a bit more complicated than the Ross.  If it's not a Ross then it might be very difficult or impossible to make that mod to the circuit without compromising the circuit design of the Ross.

Phillip

[ragtime8922]

I don't know if it's a Ross clone or even based on the Ross. I tried the pedal a little while back and I liked it but couldn't look inside as I was at a music store. Well, I don't want to compromise the circuit that's for sure. Oh well, just thought I'd look for some forum magic. Thanks Phillip.

[ragtime8922]

Phillip, do you have a schematic for the Carl Martin?

[Mark Hammer]

Essentially what you want is an LED that shows you the envelope follower signal, right?

I honestly don't know exactly how to do this, but my guess is that it is gonna take another transistor and at least 2 resistors (for biasing and current limiting) to drive the additional LED.  I suspect it would be fed from the junction of the 10uf cap and 150k resistor.  Note that this would only correspond to the amplitude of the envelope signal.  The actual amount of gain reduction would depend on how the 500k pot is set.  So the LED would conceivably be able to tell you that there was a *reason* to reduce gain but that the unit presently was not doing anything about it.

A circuit to indicate how much gain reduction was taking place is a horse of a different colour.  I picked up an old Ashley compressor/limiter this summer, and it has a 4-LED meter indicating how much gain reduction is taking place (which is sort of what you want).  Damndest thing to look at, because the LEDs are stacked in a such a manner that all of them light up if the unit is only lightly grazing the signal, and only one lights up if you're in ultra-squish mode.  Confusing, huh?  Not if you reason that it is showing how much signal is being LET THROUGH.

It's a pretty complicated circuit, though, likely more complex than the Dynacomp/Ross itself.

[phillip]

Nope no schematic...I just went to the Carl Martin page and looked at the pedal.  Has double the knobs that the Ross has so I was thinking that it might not be a Ross circuit since it would be hard to find a place for 2 extra knobs in the Ross.

Phillip

[ragtime8922]

There you are Mark, thanks.

The LED (Single LED BTW) lights when the unit is compressing but the way it gets brighter and then softer reminds me the way LED's light and fade when used as clipping diodes from the output of an op-amp to the inverting input. (That's the actual app I am referring to right now) I was thinking it may be simple like that. I'll be back in town today but my breadboards are tied up right now. Damn, I want to try and do this now. Anyway Mark, thanks for your thoughts and expert advice as always.