amp quiet with a compressor in effect loop

[Tdale]

I modified a DC30 that I built, adding relay switching and some other stuff. The guy who bought it discovered that if he puts a Carl Martin compressor in the effect loop of channel 1, all hiss and buzz goes away!

Any idea why this is? Maybe I should start including a gutted Carl Martin in the signal chain to keep it quiet?

Tommy

[benoit]

Is it just that compressor or is it anything in the effects loop? What if you just connect a cable from the send to the return? If that has the same effect as the compressor maybe one of the jacks is not properly grounded? I don't have a ton of experience but that's my two cents.

[Tdale]

I'll try a wire.

When there's nothing in the loop, the jack shorts, so that should do the same thing as a wire would..

By the way, it's a stereo jack, with the tip as "send" and the ring as "return", so the grounding should be the same, with or withouth anyhting plugged in...

Tommy

[brownnote]

Having a wire in the loop actually does do something different...it adds a small amount of capacitance and resistance equal to an R/C network.

IIRC some loops use a 220R and 10pF instead of a direct connection when nothing is plugged in.

Try using different lengths of cable and see how it affects the performance.

[novosibir]

... that if he puts a Carl Martin compressor in the effect loop of channel 1, all hiss and buzz goes away!

Maybe the reason for the buzz and hiss w/o anything plugged in simply is a dirty/oxydated switching contact on the Return jack?

Put in a patch cable from Send to Return, to verify this!

Larry

[brownnote]

... that if he puts a Carl Martin compressor in the effect loop of channel 1, all hiss and buzz goes away!

Maybe the reason for the buzz and hiss w/o anything plugged in simply is a dirty/oxydated switching contact on the Return jack?

Put in a patch cable from Send to Return, to verify this!

Larry

Good point...I've had the same problem before.