I see this is a somewhat old thread, but no doubt this issue is recurring for some people.
I have been searching for a pretty long time on google about an issue with a crackling, almost static type sound coming from only the right ear side of my HD600 (which, I give thanks to these forums as I lurked and read plenty of reviews on them, as I wondered which set to purchase).
I am in no way an expert, so I can't tell you if we have the same problem, but this, and a few other threads that I finally found seem to be the closest explanations. It occurs with somewhat louder bass, in just the right side, no matter how the HD600s are driven. My setup consists of an optical cable coming from a USB port, into my Zero DAC/AMP, with that outputting into an APHEX 204 (since I wanted to, at first, EQ audio externally from my computer, and after researching, found that this, in a roundabout way, was more in line with what I had in mind), and, finally, to my HD600s.
With all of that intro out of the way, the main reason I am posting, is that the sound did seem quite like something in the right side was 'loose' causing this rattling static sound only present with bass. I tested some audio files that swept from 0-100 hz at all different volume levels, finding that the noise was not present with the volume below 40% or so on my DAC/AMP used in the preamp mode, yet it was present with preamp off, or at any higher volume. This had been occurring until just a few minutes ago. I found someone saying that perhaps a hair was somewhere inside the headphone, and although it seemed like a hair couldn't possibly result in that much interference, I opened the headphones and saw what did look like a hair against the "plastic bubble" which oscillates at the frequency of whatever is coming through the headphones. To be more certain, I played the bass sweep noise, and watched as the little white root of the hair banged on this diaphragm like a bass drum mallet as its oscillations sped up. I very carefully, with a tweezer, pulled on the hair, and it turned out to be a lot longer than it at first appeared, seeming to have been wrapped under the plastic. After plugging it back in after a thorough cleaning of the pads and gently blowing away any other hair/lint I could find, both sides sound perfect once again with no crackle/distortion/rattle with bass at any volume.
So.... maybe I am lucky and was able to see the hair before it fully retreated under the diaphragm, or maybe it is an entirely different cause. I know that with a set of David Clark Aviation headphones that I once foolishly used with a Fender guitar amp, that turning the volume up much at all results in a painfully loud crackling static, so I know that there can be more than one cause for this. However, since I learned this, I figured I'd share it with anyone else who has this issue, and let you know that maybe there is actually something in the headphone that is out of sight, to which I can only say, good luck in finding a way to get it out without further damage to the fragile components within it.
My apologies for the length here, just would hate to leave something out that could be useful without knowing, seeing as how I am not as knowledgeable as most of you here.
Thanks everyone.
