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Strange ground loop...?

Hey,

I just hooked up a new amp and I'm having a strange noise issue. Only in my right channel, I get this high-pitched whine... maybe around 2khz. My left channel is dead silent.

The problem seems to be an interaction between my DAC and my amp. If the DAC is off, the amp is silent.

The amp is an 84' yamaha, so the cord has no ground. There is a ground screw, though, and I have connected that to my power conditioner, hoping this would solve it... nope.

I've tried plugging the amp straight into the same outlet that the power conditioner is plugged into (into which the DAC is plugged in). That actually did work... but I don't want to run my amp straight into the wall.

I suspect I just need to find a proper place to run that ground wire...

Any ideas?
djembeplay
djembeplay OP
169 posts
 
Hmm... interesting. Well, the cord is already going back... but that's good to know for the future.

Any chance the static distortion did speaker / amp damage? Everything sounds fine, but I would like to know if such distortion is the same as amplifier clipping...?
Post removed 
jea48
2,944 posts
 
Hmm, no phono in... just a pair of RCA's. It's a Yamaha M-40 power amp.
03-07-09: Djembeplay
LOL, sorry about that.... I must have had a brain fart, LOL.
For some reason I was thinking preamp in regards to the ground screw...
DAC > to > preamp.....

At any rate I would not connect the chassis of the amp to earth ground.

As for the non polarized plug it might be worth your time to check for the proper AC polarity orientation for the power transformer of the Amp. http://www.boundforsound.com/tweak.htm
=========

Glad to hear you found the source of the buzz.
.
kijanki's avatar
kijanki
3,575 posts
 
"If the cable is coax, the shield connected at both ends of the cable."

Bob - I was talking about interconnects.
djembeplay OP
169 posts
 
Ok... I have to revive this thread. I just received my new replacement cable as well as a new passive pre-amp. I hooked everything up and **suprise!** the whining interference noise is back in full force!

So, I started to switch around the orientation of my interconnects. I have one from my DAC to my pre and the other from my pre to my amp. Pretty standard.

Now, I have found a configuration that works pretty well, but not perfect... there is still a very faint 'whining' noise when my volume on my pre-amp is set between 8 and 11 o'clock. Beyond that, it's dead silent.

Now, tell me how this makes any sense... at all:

Let's say interconnect 1 has terminals A and B. Interconnect 2 has terminals C and D.

Here here my results, running sequentially from DAC to pre-in to pre-out to amp:

A-B-C-D : loud whine
A-B-D-C : loud whine
B-A-C-D : loud whine
B-A-D-C : loud whine
C-D-A-B : loud whine
C-D-B-A : loud whine
D-C-A-B : loud whine
D-C-B-A : dead silent except for faint whine at low volume

I don't get it... at all. What gives? If it's a shielding problem, then shouldn't configuration A-B-C-D also work just as well?

What should I do?
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