Grounding issue with HiFiman Edition XV

[antcollinet]

but when i unplugged the amp and dac from the power socket, hum is there. Only when I unplugged it from laptop usb port, it goes away

Hang on - where is the hum coming from if it is still there with amp and dac disconnected. Are you talking about hum coming from a device - rather than from your 'phones?

In any case - if the hum only comes when you plug in the USB cable - using TOSlink will eliminate it because then there is no electrical connection between PC and DAC.

 

[winsome]

apologies, let make it clearer. I unplugged the dac and amp from power socket entirely, hum still there. When I unplugged the usb cable from laptop, it goes away, even when I plug Amp/dac to the electric socket.

Strange thing is that at the state of the amp/dac unplugged, when I touch the casing, hum goes away even when usb is plugged

 

[antcollinet]

apologies, let make it clearer. I unplugged the dac and amp from power socket entirely, hum still there. When I unplugged the usb cable from laptop, it goes away, even when I plug Amp/dac to the electric socket.

Strange thing is that at the state of the amp/dac unplugged, when I touch the casing, hum goes away even when usb is plugged

But still my question - if your amp is unplugged, what is humming. Your headphones? Your Amp itself? your dac? your PC? (obviously if your amp is unplugged it can't be driving hum into your headphones - hence my confusion)

It might be helpful if you sketch your system - what is plugged into what, by what type of interconnect, - where.

 

[AnalogSteph]

It's pretty clear that there is mains leakage from the laptop power supply traveling via headphone cable ground return to listener to ground in this case.

The only odd part is that I would expect big planars to be too insensitive and fairly well-insulated from the listener to clearly show this effect. I've only experienced it on in-ears before. Mind you, perhaps the construction of planar drivers + ear distance results in a bunch of capacitive coupling here, who knows.

 

[winsome]

But still my question - if your amp is unplugged, what is humming. Your headphones? Your Amp itself? your dac? your PC? (obviously if your amp is unplugged it can't be driving hum into your headphones - hence my confusion)

It might be helpful if you sketch your system - what is plugged into what, by what type of interconnect, - where.

sorry for the late reply. when i unplugged either amp or DAC, the headphone is still humming.

System wise is simple, PC to DAC to amp. Dac is smsl D400ES, amp is gustard. Balanced cable between DAC and amp. USB cable is wireworld ultraviolet. Stock power cable from both amp and DAC. Headphone like i mentioned above is Hifiman HE600

Now the even more interesting update : I'm bought some cheap aftermarket XLR termination balance cable, the hum is even more evident and even audible when song is playing at right channel. The system is located on the right hand side near where I sit in front of computer on a rack. HOWEVER, when I look/tilt my head to right side, hum goes away. And this hum goes on and off, sometimes its there, sometime not.

PLUS, I just got a new headphone, ZMF Atrium, no hum whatsoever. I already bought a neutrik XLR and looking to build a new cable for the HE600

Additionally this hum also happens on my son setup. His is Aune N7D with Hifiman Ananda Unveiled. If this is a QC issue then I strike a huge jackpot for a problems with both headphones? I wont be totally suprised knowing QC of hifiman or I probably need to go to sorcery/voodo forums than audio with this.

 

[winsome]

Folks, just got a new set of cable, with a decent IC ,neutrik xlr and oyaide 3.5mm - but its a TRRS ,not TRS. Have read there are compatible and can be use for audio only. The hum or buzzing still there. Still the same symptom as described above. To add, hum or buzzing sound appear after some time playing, not immediately.

I really want to like the HE600, I believe its very close or maybe equally good as Atrium. But with this hum, its just unacceptable. I started to think its the headphone now that's the cuplrit

Can someone chime in and give explanation on what is going on? Thank you

 

[solderdude]

Can someone chime in and give explanation on what is going on? Thank you

There probably is a large amount of RF being picked up by the headphone cable and the amp it is connected to is probably not well designed in this aspect ?
Possibly some 10nF capacitors directly at the output or perhaps even a clamp-on ferrite with the cable looped 3x trough it as closes as possible to the headphone out of the amplifier may cure the issue. No guarantees.

Try to borrow another amp somewhere and see if the problem goes away.

 

[winsome]

thank you. But if that is the explanation how come it didnt happen to the atrium? Because its less sensitive? The stock cable on the atrium have no ferrite