SSL 502 Problem

[barthman.de]

I racked two ssl 502 EQ's some time ago. They work fine. A acquaintance has 5 modules (not racked yet). He powered the modules with 5 rail psu from JLM Audio. He told me, that he have feedback problems on all modules and all EQ bands (LF, LMF, HMF, HF). Every time if he turn the gain poti more than 3dB he has a feedback that sounds like self oscillation. Anybody heard about this problem? Could it be the poti's? Because the problem is on all modules and all eq bands I think this is unlikely. He told me that the modules are not balanced. 

[squib]

I reckon there are trimpots on each band that set max Q, if set too high the band will oscillate. If this were the case the freq of oscillation would be dependent on the freq select pot. Does this seem to be the case? Seems unlikely that ever trimpot is out of wack unless some random timpot twiddling has taken place....

[Dr_J]

Hi Bartman,

I'm not sure, but if I remember right I had a "strange noise feedback" sound when I racked mine and we mailed (Thanks again ). I guess first I had a wrong pin connection!??
But I'm not sure, but maybe better check it.

ROCK-ON!

[barthman.de]

I reckon there are trimpots on each band that set max Q, if set too high the band will oscillate. If this were the case the freq of oscillation would be dependent on the freq select pot. Does this seem to be the case? Seems unlikely that ever trimpot is out of wack unless some random timpot twiddling has taken place....

Sounds good, we'll trying it.