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Dreaded Hum in new set up with dedicated line (1 Viewer)

Gary Hunter

Agent
Joined
Nov 12, 2003
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36
Time for an update and more advice. My electrician came back to town with the flu and is laid up in bed. So I decided to go ahead and give some of your ideas a whirl on my own.

1st I tried new receptacles in case the outlets were bad, but that didn't help.

2nd. I moved the breakers in the box so the dedicated amps are in phase (position 3 and 7). That didn't help either.

I then disconnected the pre-amp and moved it close to the amps and reconnected only the pre-amp. In my set up, the preamp is located to the side of the room and the amps are on the floor in the middle of the room. I was then able to hook up the pre-amp via balanced cables, and RCA cables alternately. When I use the balanced configuration, the buzz disappears. When I use the single ended, and I tried 1m and 8m runs, the buzz returns. The solution may be to use balanced cables but I don't own any currently that are long enough to make the run and I feel that something is amiss in the electricals since even the short run of RCA buzzes, not just a long run.

To summarize,

No Buzz when amps are un-grounded or using balanced cables
Buzz in every other configuratiion.

Any more ideas,

Thanks guys, I appreciate all the input.

gary
 

Legairre

Supporting Actor
Joined
Apr 4, 2000
Messages
815
Try the speaker wire trick. Run a wire from the pre amp to amp1, then run another wire from amp1 to amp 2. It sounds silly but it ties all the grounds together. Also do you have cable TV running throught the pre amp?
 

Gary Hunter

Agent
Joined
Nov 12, 2003
Messages
36
OK, I'll give the speaker wire a try. Is there any particular place to attach the wires to the components?

No cable. I do now have satellite but the buzz was there before that and that audio is via Toslink and the video is connected directly to the projector.

When I was in the breaker box I did notice that the ground, bare wire, of one of the dedicated circuits was twisted with the ground of another wire, but not the other dedicated outlet. They do all ground to the same side bar though. My thougts are that the source has to be coming from a grounding issue. Anybody have any ideas?
 

Legairre

Supporting Actor
Joined
Apr 4, 2000
Messages
815
Nothing special to attach the wire to, just a screw on the chassis. I use the ones that hold the cover down.
 

Gary Hunter

Agent
Joined
Nov 12, 2003
Messages
36
Time to update for all those contributing to this post.

The electrician came but was of no help. We made sure all electronic circuits are in phase, checked and double checked the grounds, cut off all other breakers except for the equipment (dimmers, etc.). I did run a speaker wire from the pre-amp chasis to the amp chasis, and amp to amp chasis. All to no avail.

So I have ordered balanced cables and am still using the cheater plugs until the arrive (I live in a small town with no local guitar store). If my experimentation is correct, this should cure the symptoms.

Thank you all for your ideas and suggestions!

Gary
 

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