I have 3 of these FET compressors (same circuit as Compex, minus the expander). I wanted more than 3 choices of attack time, so I connected a potentiometer in parallel with the attack resistors. The "fast" attack is 500 μs, which isn't very fast, so I connected the potentiometer in parallel with R150 and R155. I was able to take the resistance down to 10 or 15 ohms and get a VERY fast attack with no oscillation or instability. Am I going to damage something by doing this?
