Several months ago, I had a conversation with Bos about a mic I own - the AKG Solidtube, and how it was making some noise after it heated up. The noise was similar to what you would hear if you took a tissue or a paper towel in your hand and scrunched it. Yesterday, I dug the mic out again, thinking I'd pop the top on the power supply to see if there were any obvious indicators - like blown caps, etc... I didn't see any issues, so, I decided to take the mic apart. After doing so, I decided that I would replace the tube - I really didn't think it would solve the problem, but I figured that while I had the mic apart I might as well... So, I took out the stock tube, which was a National 12AX7/ECC83 - and because I didn't have an exact match to replace it with, I ended up using a Mesa 12AT7/ECC81, from a box of spare tubes that I keep around. I fired the mic up again, let it warm up for about 15 minutes (long past the time the mic would have taken to start making the noise I'd been hearing ) and.... silence!! The noise was gone. I recorded some vocals through it, and found the tonal coloration to be very pleasing. It was very warm, yet with a very nice upper end edge ( not the bad kind of edge) ... it was a very pleasing "presence" yet still maintaining the warmth... I actually found it to be more appealing than what I'd heard when using the stock 12AX7. Replacing the tube wasn't at all difficult. Once I found the owner's manual online and read about out how to take the mic apart (just 3 small Phillips screws on the bottom of the mic where the power supply jack is) it took less than 5 minutes to open the mic, replace the tube and then put the mic back together. I am now wondering what different tubes might sound like; perhaps a Telefunken 12AX7? Yeah, I know... putting a Telefunken tube into my mic won't turn it into a Telefunken mic. Anyway, just thought I'd share.