Originally Posted by Piotr Ryka
Thank you for answer, but hair problem is too simple solution. I know hair influence and avoid it. And I have hairs on both sides
If none of the answers from hrlkg01, blackmore or me helped to find the cure, there are at least two more sources. If you do not have it already, please download the Service Manual : http://www.akg.com/mediendatenbank2/psfile/datei/34/k10004055d23c1050f.pdf
1.) K1000 has a very elaborate headband adjusting/tensioning arrangement. Using coils spring and a ball, parts #9 and #10 in the Service Manual.
Rarely but sometimes these can resonate like crazy, causing sounds similar to your descriptions. WARNING : if you choose to open/check for this,
best way to proceed is to work over large plate/box ( I use "baths" for chemical reactions ) - after unscrewing the two screws holding everything in question together, spring #9, ball #10 and pulleys #4 (2 pcs per one earpiece) WILL fall out - they are tiny and easy prey for the Carpet Monster. One way to adress this situation is to assemble everything back in reverse order of disasembling - with one exception; you can apply a little amount of grease on the spring 9 - that should prevent any rattling/resonances going on there. Or, if you are pragmatic as me ( read: lazy ), simply omit pulleys #4, spring #9 and ball #10.
2.) What are you driving K 1000 with ? K1000 is about as hard to drive properly as it gets - small amplifiers are incapable of supplying enough voltage swing and clipping on piano can/does sound like you described; big amps ( 100 W+ into 4-8 ohm load ) can simply exceed K1000 excursion capabilities causing bottoming, but that is normally a low and not a high frequency problem. Try different amp(s) and if the problem persists, it really is the K1000.
3. If procedure 1.) and 2.) do not cure your problem, ask yourself fairly if you ever really grossly overloaded that left driver - like pulling the RCA cable out by mistake anywhere preceding the amplifier , or switching between two sources having considerably different levels without reducing the volume when going from low output to high output source ( in extreme cases, can amount to 20 dB or so , say between output of an extremely low output MC phono cartridge and a CD player ) - in that case, I am afraid you will have to brake one piggy bank with appropriate amount in order to get new driver.
Edited by analogsurviver - 10/31/12 at 10:22pm