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Turntable/Subwoofer Ground loop

I have a Rel B1 that is hooked up to Cary MB500 monoblocks via the high level connections.

I am starting to get a ground loop hum from the sub when I play a record. Only when the needle hits the record does it start. I have re-checked all connections, what could it be?

All the ground wires are connected what I think is correctly, but the high level connection from the amps to the sub has the wires stretched quit a bit to reach the amps and the ground.

Should I ground the Sub connection to somthing different, like the rack???
macdadtexas
macdadtexas OP
1,794 posts
 
Tonywinsc,

I think you may be right. I isolated the phono cable and most of the hum went away, I need to try inverting the phase of the turntable. Good advice, thanks.
zenblaster
504 posts
 
I think you want to invert the phase of the sub, instead of turntable.
tonywinsc
583 posts
 
That's correct. just a quick way to see if the feedback is mechanical. most subs have a phase switch.
macdadtexas OP
1,794 posts
 
Sorry, I meant sub, I did that, but there is still some hum.
macdadtexas OP
1,794 posts
 
Humming more again after some improvent. Only from the high level input. When that is disconnected, no hum, and no hum from any other componenet, or when playing anything except the turntable???
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