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XLR Interconnect Causing Noise in One System but Not Another

I ran into something today that I’m trying to understand from a technical standpoint.

 

I swapped a Morrow Audio M5 XLR for an Audio Envy O’nestian XLR between my preamp and power amp and immediately heard a static / scratchy noise through the speakers. Reinstalling the Morrow cable eliminated the noise entirely.

 

What makes this interesting is that I then took the same Audio Envy O’nestian XLR and installed it in a second system between an Eversolo and a McIntosh, where it performed flawlessly. Dead quiet. No noise or artifacts of any kind.

 

I’m generally skeptical of cable claims and tend to believe that properly built balanced XLR cables should be functionally identical from a noise-rejection standpoint, which is why this result caught my attention.

 

System where the issue occurs:

 

  • Silent Angel Munich M1 (SBooster LPS)
  • I2S via AudioQuest Coffee HDMI
  • PS Audio DirectStream Mk1 DAC
  • Rotel RC-1590 MkII preamp
  • Rotel RB-1590 amplifier
  • B&W 702 S2 speakers
  • SVS SB-1000 sub
  • Monster HTS3600 power conditioning
  • Rega P2 / Ortofon 2M Blue / Graham Slee Reflex M (via RCA)

 

 

Room is a large living space (approx. 18’ x 29’), treated front wall, wood floors.

 

Given that the same cable is noisy in one chain and silent in another, I’m curious what the most likely explanations are, for example:

 

  • Shielding or grounding differences between cables
  • Pin 1 grounding implementation
  • Connector tolerances or soldering quality
  • Interaction with the Rotel input stage (impedance, grounding scheme, CMRR)
  • Sensitivity to upstream grounding or power conditions

 

 

I’m not interested in turning this into a cable debate. I’m simply trying to understand why a balanced XLR would introduce noise in one system and not another when all else is held constant.

 

Appreciate any technically grounded insight from those who’ve encountered similar behavior.

jhill387
mike_in_nc
1,250 posts
 

Yes, it's likely a bad cable.

 

052rc
78 posts
 

While its possible that the cable is bad, I don't think it's the problem. Set your DVOM to continuity and touch the test leads to the same pin on each end of the cable to find an open. For a short, put one test lead on one pin, then take to other lead and touch it to the other 2 pins. 

The noise you're hearing is most likely due to a short circuit. The problem with balanced signals is there are no standards that manufacturers must follow. There's more than one way a component can be balanced, and there's different wiring options, as well. I don't believe your Rotel amp and preamp are balanced. They probably just have xlr connectors as an input option. And even if its labeled balanced, that doesn't mean it is. If you're not sure, listen to your system with the old pair of xlr cables that work. Then swap it for a pair of regular RCA cables. If both components are balanced, the xlr cables should be noticeably louder. If not, its safe to assume one or both pieces is not balanced. Just use an RCA cable to connect them. When you use the xlr cables, you're just using 2 of the 3 pins/conductors. Its exactly the same as using an RCA. Some preamps have global gain settings on each input so you can adjust for things like the volume difference between balanced and single ended components. I assume your gear does not have this feature, because if it did, all of this would be explained in the owners manual. 

So, why do I say you may have a short circuit? Balanced and single ended operation is not compatible. If you want to mix components, something has to be done to make the connection all balanced or all single ended. A single ended connection has one hot + and one ground -. Balanced has 2 hots ++ and one ground -. If you want to make a mixed connection, something has to be done with the extra signal conductor on the balanced end. Its very common practice to combine the extra hot with the ground conductor. This may be done in the cable or the components. This is what you have to find out. If one of your cables or components combines the extra signal with the ground conductor and you plug that into something that outputs a balanced signal, you automatically create a short circuit. I think that's what's happening in your system. However, in the beginning of my post I said there were no standards. Some people will say they made a mixed connection and had no issues. And that can be true, as well. Depending on how the ground is wired, you may be able to get away with making the connection. Sometimes a ground may be floated, and you can get lucky and have no issues. But that's not always the case. If you look at gear that offers balanced connections, you'll almost always see a pin diagram right next to the xlr jack. They put it there to help you avoid making a bad connection..   

 

jhill387 OP
3 posts
 

Thank you so much for the thoughtful responses.  I have not opened the audio envy xlr to explore further.  
 

i will say that i feel like the audio envy xlr feels like its added some character to the Eversolo a6 ME / McIntosh Ma5300/Harbeth 7es3 setup.  A little more attack or slam, which I find interesting. 
 
That said this whole experience has kind of changed my opinion on the great cable debate.  

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