Afterlife with compression indicator LED. questions

[iefes]

Hey all,

I built the Afterlife compressor (old version of PCB without the potentiometer sub-board) and I quite like the result. I added the threshhold knob suggested by jon and an indicator LED which lights up when the compressor is affecting the signal.
It is working at the moment but I am not sure if I've choosen the right position in the circuit to add the indicator circuitry. As you can see in the schematic provided below I tap the signal from behind the threshhold pot/pin7 of the IC ("A"). I used another value for R1 (68k) than indicated in the schematic but the indicator LED lights up nicely when the signal gets compressed. It is also sensitive to the position of the Comp and Threshhold knobs which makes sense.

I am just wondering if you think there might be a better position to place the indicator-circuitry. At the moment the LED lights up also on the lowest settings but with these settings it fades quite quickly. It also flashes shortly when switched on from bypass. Do you have any ideas if this could be avoided?

So, yea no real issues here, just curious to learn! :-)
Any suggestions and/or explanations are very welcome.

cheers

[midwayfair]

That whole part of the circuit is in series, so it sort of doesn't matter where you put it -- you could also put it right in line with the LED half of the vactrol.

The main problem is that you lose another 1.7V of rectifier voltage when you put the the LED there. If it's working and you like how it sounds, I guess it's not a problem for your build, but ideally it would be a separate indicator circuit with its own buffer. You could do it with a single transistor, taking its base input from IC1B through a 10K resistor. Ray Ring's MOSFET compressor had a similar indicator circuit as an example, using a MOSFET, but it can be done just as well with a normal BJT (I can't remember if it would need to be NPN or PNP).

[iefes]

Hey Jon, thanks for your fast reply.
I didn't put the LED directly into the circuit but tapped the signal from where I marked and fed it into the circuit on the right in the schematics (marked with "A" in both diagrams). So there shouldn't be a voltage loss, is this right?

Thanks!

[midwayfair]

In that case you should be fine.