Hum issue - driving me more crazy


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Not sure if this should be here, Tech talk or Cables...

Audio Research Ref 2 Preamp, Pass labs electronic Xover, Bryston 4B ST amps (2), MAGGIE 20.1 speakers. All eqpt working OK.

Pre source eqpt left rear of room
spkr amp & XOVER left front of room
spkr amp right front of room

Separate 20 amp circuit for hifi eqpt. Other plugs in rooms for lamps, etc. Many of lamps on dimmers

Singlended IC's (now double shielded)are "under" flooring (pier and beam construction) & has been moved away from other wiring & cross at right angles

Initially some hum from dimmers (on separate circuit), etc. Have learned to leave them off.

But there is constant low level hum - right side only EVEN with preamp and XOVER turned off.
imdoc

Showing 2 responses by gs5556

Try lifting the grounds on the amplifiers by using a two-prong adapter. You have the perfect setup for ground loops -- all equipment plugged in multiple outlets spaced far apart on the same circuit along with interconnects running the length of the room.
Bringing the cable above the floor may be moving them away from fluorescent ballasts. Speaking of lights, do you have any low voltage LED or decorative lighting that feeds off a DC transformer? These introduce DC into the wiring that get into ground loops.

To answer your question: yes, balanced IC's are the best way to go because the shields are tied to the chassis instead of signal ground. But somewhere, there is something that is amplifying your problem -- computers, improper CATV or Telco grounding, etc.