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
 
Anyone? What is a cable that has a return through the shield?
kijanki's avatar
kijanki
4,432 posts
 
"Anyone? What is a cable that has a return through the shield?"

- That's cable with only one wire (signal) inside and shield serving as second wire (ground/return). Coax cable is an example (BlueJeans cable is made of coax cable).
djembeplay OP
179 posts
 
So is this sort of interference problem known to occur sometimes with this type of cable?

Does this problem I'm having mean my DAC has a problem?
Post removed 
djembeplay OP
179 posts
 
Well I took the DAC out of my system last night and hooked it up to a second system using LC-1 for the output. The same interference noise occured

I had three pairs of LC-1 cable and tried all three as outputs from my DAC to my pre, and they all had the same problem.

If I switch cable, everything is great. If I use the LC-1 to run straight from my DAC to my amp, everything is great. It's only when running LC-1 from my dac to a pre-amp that things get ugly.

Here is my system:

Digital feed from PC via Blue Jeans Digital Coax ->
Audio Mirror D2 NOS DAC ->
Blue Jeans LC-1 ->
Richard Lee Audio Passive Pre-amp ->
Blue Jeans LC-1 ->
Yamaha M-40 ->
Blue Jeans (Belden 5000) speaker cable ->
Green Mountain Audio Continuum 1s ->
Ears.

For power:

-Computer is on separate power conditioner (this isn't the problem as I experienced the noise with the computer turned off)

-DAC and amp plugged into Furman Elite 15i. DAC is fed by Iron Lung Jellyfish power cable, amp by it's stock power cord.

That's it.

You mentioned the 'loose connection' thing... and I was thinking of something along similar lines. While nothing feels loose, the connectors on the back of my DAC are considerably long. What if the farthest I can push in the LC-1 onto these connectors just isn't enough to make contact with something that is necessary. I don't really understand the details of how this works yet, so this is a shot in the dark...
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