Built this as a commissioned request for a diamond bass comp. I found this pcb from lectric-fx made to fit in 1590B. I referenced the fsb diamond bass comp thread to find the value changes to make it like the bass version. The toggle switch on the side the is tilt EQ frequency (900/250Hz), dpdt with the caps soldered you it.
the fourth knob is a clean blend. The little daughterboard down by the ftsw is an Op-amp based inverting buffet circuit for the clean side of the blend pot. I know there’s some question as to how necessary a blend knob is on an optical comp... just turn the comp knob down and it sounds like the dry signal. But, this was a customer request, and I think gives some opportunity to intuitively dial in the attack and sustain since adding clean will help Preserve attack.
Anyway it turned into a pretty involved build, but I’m super happy with how it turned out and sounds great. Considered getting another pcb to build the simple guitar version for myself, but I also just built the pale green comp and these are in the same ballpark.
the fourth knob is a clean blend. The little daughterboard down by the ftsw is an Op-amp based inverting buffet circuit for the clean side of the blend pot. I know there’s some question as to how necessary a blend knob is on an optical comp... just turn the comp knob down and it sounds like the dry signal. But, this was a customer request, and I think gives some opportunity to intuitively dial in the attack and sustain since adding clean will help Preserve attack.
Anyway it turned into a pretty involved build, but I’m super happy with how it turned out and sounds great. Considered getting another pcb to build the simple guitar version for myself, but I also just built the pale green comp and these are in the same ballpark.