2. amps-preamps
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Hum issue - driving me more crazy

Page 1

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
arnettpartners
312 posts
 
If you haven't run a ground from pre to amp, you need to try that and maybe with xover. If the gear doesn't have a ground terminal, loosen a cabinet screw and attach.
gs5556
1,209 posts
 
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.
rwwear
2,847 posts
 
You really need to run the system balanced if possible.
Post removed 
jea48
4,283 posts
 
But there is constant low level hum - right side only EVEN with preamp and XOVER turned off.

I agree with Gs5556. Try some ground cheaters.

Just because you turned off the preamp and xover that would not break the ground loop current path through the right channel amp.

Have you tried to isolate the right channel amp from all other equipment? Nothing connected to the input of the amp... That would tell you if the low level hum is caused by the amp or not.
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