Getting desperate and annoyed,
Murphy
The simplest ( though not cheapest ) solution is to provide the offending component ( the Behringer unit in this case ) with
Galvanic Isolation ( in the form of ground lifted, audio transformers ) .
(i) Here's a set . You should ( hopefully ) only need them on the output of the 1124 .
- Jensen Transformers are TOTL ( spec wise ) & quite transparent in the circuit ( more so than even the Behringer unit that they would follow :whistling: ) .
(ii) Here's a much cheaper solution at @ 1/5 the price ( though utilyzing the same approach of providing galvanic isolation with ground lifted transformers ) .
- These are just "alright" ( spec wise ) and within a clean circuit ( not yours at the moment ) are apparent ( to the trained ear ) when they are inserted into the signal chain .
- I'd recommend starting with these & then moving on to something better ( if you figure the system warrants the extra monies spent ) .
NOTE : The Urei/JBL 6290 amp ( & the rest of that series ) are pin 3 hot .
6290 OM pdf
- Your Lexicon unit ( like all newer balanced electronics for the last couple of decades ) are pin 2 hot .
- Mixing electrical protocols ( such as you are ) can often lead to hard to trace noise problems / especially with single phase electrical services ( that may already be at a tipping point / current balance wise ) .
- (FWIW ) if those were my amps, I'd modify their front ends & rewire the XLR connectors ( by simply swapping the wires at pins 2 & 3 ).
:sn:
