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SOLVED: Topping E50/L50 combo + Audeze LCD-X = leakage current?

KomoGomolaa

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Hi there. Need your help please. i'm running a wonderful Topping stack consisting of following items:
- Topping E50 dac (connected with Topping HS01 isolator to Mac Mini M1 and powered by Topping P50)
- Topping L50 hp amp (interconnected via balanced TRS)

I have received my brand new Audeze LCD-X (2022). Besides I also have HD800 and Audix A150 - no problem with these.
The "problem" is that when I accidentally touch the earcups or mini xlr connectors of Audeze LCD-X, i can hear a buzzing sound. It's of less significance, albeit still there, when i lift my feet off the ground.

So I did some research on the net and found that it is most probably leakage current somewhere occurring when I give my body as a ground when simply touching the earcups. So there must be something ungrounded in my setup, and looking at the L50, i suspect it's the victim because it is using the beefy AC/AC adapter with no ground. I have tried to disconnect the dac from it and the buzzing is still there.

i thought i would get rid of it, so tried to convert the stock SE Audeze cable to a differential one (the 4-pin xlr to L50 is basically ungrounded because Audeze cable uses only 4 wires - L+, L-, R+, R-), but it didn't help either - it made the buzzing in right earcup slightly louder, which is interesting because single ended buzzing was circa the same level in both earcups).

I thought that when i connect L50 to a grounded dac (i suppose E50 is), the leakage current would be able to escape, but it seems like in my setup it's not the case.

Also i'm not the only one who experiences the very same problem with Audeze headphones, there are reports on other forums too, even with LCD-5...

So the obvious question is - can this be somehow solved? Any help would be appreciated. Should I remove HS01 (because in some way I'm breaking the ground of the dac) or should I connect the chasis of the L50 to the earth ground?

I really like the way how E50/L50 sounds/works for me and don't plan on replacing it anytime, for now I consider it the second best totl dac/hp amp behind the D90SE/A90 combo).

Thank you very much in advance for anything that can help me solve this issue.
 

Tks

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I'm certainly not qualified, but do you think you can attempt to try this without the isolator? Or see how the setup functions using direct USB to the Mac Mini without the isolator?

Likewise, would you be able to try and connect direct to the mac mini with the headphone cable itself? I recall those have a 3.5mm jack in the back (though I don't know if you have an unbalanced cable anymore). As far as buzzing increasing, that's the downside with balanced, noise doubles. The reason one would use balanced in the first place (besides a doubling of output power as an aspiration) is to lessen so called ground loop potentiality. One hopes the source of buzzing or noise they hear is a ground loop, but when it isn't, you basically have this doubling of noise (which usually isn't a problem since most setups have noise way below threshold of hearing, but when you have issues like you might have, you get this worst kind of scenario).

I have no idea what sort of grounding scheme Topping is using for their devices (could be "floating ground"). It would explain why there is no reduction in the buzzing, since it isn't a ground loop in virtue of floating grounds making this a non possibility if my extremely novice comprehension of electrical systems is correct.

I wish someone would make a video or basic write-up for a layman of all these sorts of configuration issues that can arise (that takes into account the sorts of possible things headphones and speakers can induce when they're at the end of this chain) with respect to these artifacts in audio setups. It seems something anyone with some basic electrical engineering insight already knows, but with all the possible audio setups and other devices being used on the same socket, it's something I haven't been able to grasp and visualize properly (nor diagnose without doing the brute-force-try-everything-until-diagnosed sort of way).
 
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KomoGomolaa

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Thanks all for your replies.

I'm happy to report that i've just tried my combo without the isolator and the buzzing is gone, yess!!!

Seems like the isolator is cutting the ground off in my setup, which is "incompatible" with my LCD-X.

Please note that i'm not blaming the isolator - it's doing wonderful things in my brother's setup where he was constantly experiencing noise problems with his dac/adc during recording sessions, so I thought it would be good for me too, that's why i started using it.

I have marked the thread as solved.
 

AnalogSteph

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I bet it's mostly capacitive mains leakage from the E50's power supply, which at 5V DC presumably is a switch-mode job (the L50 has a 15 VAC transformer plug pack with very little mains leakage). With the isolator in, audio ground is floating at part of the mains voltage, while you are pretty much at earth potential. It just isn't something I would have expected to see with planars, I've mainly encountered it with far more sensitive in-ears.

The Mac Mini is probably grounded through the monitor or something, and that promptly drains the offending mains leakage and pulls audio ground down to earth.
 
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