Help! I need a scientist!

[PointyFox]

It's not the amp. My headphones still buzz when both the amp and headphones are unplugged.

 

[ADUHF]

Crossed posts. See my last post above.

 

[PointyFox]

Hmm. The humming gets louder with the power supply for the energizer plugged in. Power contamination is causing EMI maybe?

 

[ADUHF]

Hmm. The humming gets louder with the power supply for the energizer plugged in. Power contamination is causing EMI maybe?

Perhaps. FYI, the fact that the problem persists even when the headphones are disconnected does not necessarily rule out the amp (or its supply) being a contributing cause of the issue.

I still suggest you should contact Koss customer support. Because they've undoubtedly had other service calls of this type. And may have some other ideas how to resolve it.

This is from the last link above though...

if you read through the esp950 thread on headfi the biggest improvement you can do for these headphones is upgrading the power supply.

 

[PointyFox]

Just spoke to the amp/dac manufacturer, they said the amp/dac is working fine.

It's so strange. When I coil the ESP/950 headphone cable while it's not connected to anything, it picks up hum when I touch it to any part of my desk or things that are on my desk, like a water bottle. My desk isn't conductive. Not sure how it would conduct EMI.

 

[ADUHF]

I'm not sure if this is your issue. But static charges can build up on non-conductive surfaces, such as plastics or glass.

Did the mfr say anything about the power supply?

 

[megabigeye]

Just spoke to the amp/dac manufacturer, they said the amp/dac is working fine.

It's so strange. When I coil the ESP/950 headphone cable while it's not connected to anything, it picks up hum when I touch it to any part of my desk or things that are on my desk, like a water bottle. My desk isn't conductive. Not sure how it would conduct EMI.

This sounds like it may be creating an inductive coil. Try running a magnet over the cable while it's coiled, but be careful with the magnet near the drivers. Or it could be that the magnets in the drivers are interacting with the coiled cable to create an inductor?

When I worked retail, we sold extension cords that were coiled in their packaging. They didn't have magnetic security stickers, but they would set of the alarm unless you run them over the demagnetizer.

 

[ADUHF]

Is the room where you're using these air-conditioned or unusually dry? If so, then perhaps that might be contributing to a buildup of static charges (and weak electrical fields) in some non-conductive surfaces in the room.

 

[PointyFox]

This sounds like it may be creating an inductive coil. Try running a magnet over the cable while it's coiled, but be careful with the magnet near the drivers. Or it could be that the magnets in the drivers are interacting with the coiled cable to create an inductor?

When I worked retail, we sold extension cords that were coiled in their packaging. They didn't have magnetic security stickers, but they would set of the alarm unless you run them over the demagnetizer.

Attempted to, but couldn't hear anything. I'd imagine I'd have to move it pretty fast to create an audible frequency.

 

[PointyFox]

Is the room where you're using these air-conditioned or unusually dry? If so, then perhaps that might be contributing to a buildup of static charges (and weak electrical fields) in some non-conductive surfaces in the room.

72 F and 31% RH

 

[megabigeye]

Attempted to, but couldn't hear anything. I'd imagine I'd have to move it pretty fast to create an audible frequency.

I meant to try to demagnetize the cable with another magnet, not to create more noise. But if it didn't work, it didn't work.

 

[PointyFox]

I meant to try to demagnetize the cable with another magnet, not to create more noise. But if it didn't work, it didn't work.

Oh, I have an industrial demagnetizer... not sure I want to bring my headphones anywhere near it though

The cables themselves aren't magnetic though.

 

[ADUHF]

I meant to try to demagnetize the cable with another magnet, not to create more noise. But if it didn't work, it didn't work.

I would be hesitant to put anything magnetic near my HPs. But would a (semi-magnetic) ferrite core work for something like this, attached near the plug? Or would that interfere too much with the sound?

 

[ADUHF]

72 F and 31% RH

So yes on the A/C then? 31% RH is a little low. I'm not sure if that is low enough to be a real factor though.

 

[megabigeye]

Oh, I have an industrial demagnetizer... not sure I want to bring my headphones anywhere near it though

The cables themselves aren't magnetic though.

Yeah definitely keep that thing away from your headphones. "Oh, look! I made a headphone-shaped door stopper!"

Do you keep the cable coiled? If so, maybe uncoil it?

I do agree with ADUHF: you should exercise extreme care when using magnets near your headphones. But I think you already know that.