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DIY XLR cables & amp distortion

gandalfandula

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I recently made some diy XLR to XLR cables for my audio system. I was careful to solder everything correctly and used a multimeter to check the pinouts on both ends to verify continuity and correct wiring - all pins are connected correctly and the shells are not conducting anything to the pins.

I tried the cables with my Monoprice THX AAA headphone amp and Benchmark DAC1. Though they do work I noticed on the high gain setting on the amp that it sounds very obviously distorted with my HD650 300 ohm headphones. I am wondering if this is something to do with a mismatch between the XLR output on the DAC and the input on the amp, or possibly the amp just doesn't sound good at high gain over XLR? I tried using the single ended outputs with a pair of cheap retail stereo audio RCA cables and there was no distortion at any gain or volume level.

Could it be something with the cables?

I tried my other DAC with the XLR output and it didn't seem to have the static/distortion issue. I think the XLR output on the DAC1 might not be copacetic with the headphone amp's high gain setting. Maybe the gain is too high?
 
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gandalfandula

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My bet would also be that you're clipping the signal somewhere in the chain.
I think that's what it is too. I'm not sure what the pots are set to on the XLR output and it's probably too hot for the high gain setting on the amp.

To eliminate the obvious:
Did you use a Shielded Twisted Pair (STP) bulk cable?
I used Mogami W2552. I don't think they are actually twisted, would that matter? They are 6' long. The cables are shielded though.

I learned about the Canare star quad after I had started assembly so I'm not sure if that would be better.
 

DVDdoug

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or possibly the amp just doesn't sound good at high gain over XLR? I tried using the single ended outputs with a pair of cheap retail stereo audio RCA cables and there was no distortion at any gain or volume level.
Is the XLR connection "louder" with the same volume/gain settings? Clipping is caused by overdriving somewhere in the signal chain... It's not necessarily the output to the headphones.

Shielding and twisting don't affect the signal level or distortion. They are ONLY related to noise pick-up. And in the real world you probably wouldn't get any (audible) noise with an unshielded and/or untwisted connection. Those things are much more important with a microphone, which has a much lower signal and any noise gets amplified 100 or 1000 times along with the signal.
 
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