Hello,
I have some trouble to set up the FET transistor (BF245). I cannot hear or notice anything different when I turn the P6 trimpot. The  DC value I get when testing TP6 is around -5V, which seems too high. Everything else seems to work perfectly but the device is not compressing... 
Can the transistor be broken? (or not suited I try to put a BF245b that I had instead and there is no difference).
Should the transistor be connected to R3 ? 
Thank you for your answer !!