Keeley 4-Knob Compressor

So close to the Ross Compressor that the 2-knob versions seems to be essentially verbatim, but I thought the 4 knob version was worth adding for the additional Clip and Attack controls.  In the original the onboard trimmer isn’t used and instead two 1K resistors were used between the bottom lug of the (top left) 220K and IC pins 2 and 3.  Rather than adding fixed resistors I thought it made more sense to leave the 2K trimmer and suggest leaving it in the dead centre position for the stock setting, and so allowing the Clip pot to perform that task, which would mean that you will have some additional tweaking capability to set the base input level using the trimmer which you wouldn’t get from the Keeley.  So maybe this can be the 4½-Knob Compressor! :o)

Info from RK about the original:

After a few people mentioned wanting to use resistors instead of the trimmer and so mean that it’s one less “special item” you have to get in, here’s a rejigged revision with the 1K resistors.  I still think I’ll build it with the trimmer because I like the idea of that fine tuning ability, but you can build whichever version you prefer.

BOM: