Edit -- Doh! The Sloth beat me to the button! Thanks Daniel!
Quote:
Originally Posted by trains are bad 
So you experience noise even when not moving the volume control?
I have an old Total Bithead that is being noisy for some reason; I was just about to send it back to Headroom to have them look at it until I looked at my checking account and Headroom's rate for out-of-warranty work ($50/hr). Maybe I should try blowing it out first.
Headroom volume controls often scratch when you adjust them, but mine has always been quiet when I was not fiddling with it.
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The scratchy pot in the old AirHead is virtually by design and there's nothing you can do about it. We got so much grief about it we changed the design in the latest version. Basically, in a single power supply design the audio signal is not a zero volts average. We used a design that had the fewest possible caps in the signal chain, but had the undesirable problem that the DC offset of the audio signal went through the pot. When you adjust the pot it amplified the surface noise of the pot because of the offset. In the latest edition we put a DC blocking cap in before the pot and the symptom went away. We made other real improvements too, but putting the DC blocking cap in there did give the sound quality a hit, but on the whole the new units sound better than the old.
So don't send your AirHead in, there's nothing wrong with it, the noise isn't there when you are not turning the pot.
On the new units I believe we use seald pots, I don;t think spraying stuff from the outside will clean the pots. I'm also surprised you hear noise when turning the pot because since they are sealed it shouldn't really happen. If you have significant noise when turning the pot you should get ahold of
mikeo@headphone.com and inform us of the problem.