Poor-Man's Leveling Amplifier (One-tube opto comp)

[OneRoomStudio]

I was working on other projects recently, but finally got a chance to work on this. I borrowed the sidechain from @JLM Audio and had a lot of help from @ruffrecords on the tube circuit. The resulting design is nothing all that new, but it is a way to build an inexpensive tube opto compressor. Here's the working schematic:


I think I'm going to design separate PSU and channel cards so (hopefully) two channels can be built into a 2U enclosure. Anyone have any feedback?

Note - I'm intending to use a bicolor LED with SW4B and it's not configured correctly yet.

 

[k brown]

Is there really any compression going on? - looks like a simple limiter.

 

[OneRoomStudio]

Is there really any compression going on? - looks like a simple limiter.

It has a fairly-standard opto side chain that results in ratios similar to LA-2A/LA-3As.