Ward beck m703 limiter mods

[diggy fresh]

Hi, i'm messing around with a Ward beck m703 card, basicaly a preamp with a built-in limiter intended for intercom/talkback.

I managed to get more bandwidth but i wanted if possible to have variable attack/release.

It is a fet based limiter. According to the manual, attack and release is controlled by the time constant of R21 (22meg), R22 (100r), R23 (2.2meg) and C10 (1uf).

I tried replacing r21 with a pot but all i could get is bad thumping.

I'm kinda clueless, how do i vary the time constant?

Let me know if you want better pics/more info.

Thanks!

 

[RoadrunnerOZ]

A better copy of the whole schematic would be good.
You could always try using a rotary switch and switch in different capacitor values for C10 - so a stepped time constant change rather than smooth variable or put a low value pot, like say 1K, in series with the capacitor and see what happens - it looks like it’s reliant on the charge time of that capacitor.