2. amps-preamps
  3. 1236409165

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
179 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?
djembeplay OP
179 posts
 
Ok... definitely frustrated now.

Even with configuration "D-C-B-A" when at volumes other than 'full' on my pre-amp, I get this really fuzzy, static interference when lower frequencies are strong (deep base).

This is the second passive pre-amp that has done this and it is a different make than the first... sooooo, I think it's safe to rule that out at the culprit...

It's these cables I bet... They are BlueJeans cables, though... I thought these were supposed to be pretty good???
kijanki's avatar
kijanki
4,435 posts
 
"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?"

Shield should be grounded on the receiving end (in my opinion) so your configuration D-C-B-A suggests that terminals C and A have shield grounded.
Post removed 
djembeplay OP
179 posts
 
Another update -

I just swapped out one of the BlueJeans ICs with an old Monster IC I had and the problem is completely gone... no whining or distortion at all.

Unfortunately, I don't want to use my old Monster cables... so I guess I will have to send all my BlueJeans cables back and get something else. Bummer.
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