I have a $49 Nady SCM900 (large diaphragm condenser) that never really sounded right, always sputtered with any kind of spl apllied to it. So after it being shelved for a couple years I did some web research and found a really great way to get rid of it dropping out/sputtering and at the same time really bringing it to life (the dynamic range before was awful). The trick is to get the drain voltage on the one fet in the circuit (the other trannys are general purpose devices) down to 10vdc. Mine was over 20vdc. So after finding this thread - http://www.prodigy-pro.com/diy/index.php?topic=14003. I decided I would try my own approach (as the mic. in the thread was a bit of a different layout than mine) This involves removing one resistor r7 (which is connected to drain and terminates to ground on opposite board) and replacing it with a mini pot wired as a variable resistor, the resistor (r7) I removed was a 2.2k, I didn't have a 5k mini pot so I used a 10k mini wired as a variable resistor (top end of r7 to left leg of pot then bottom end of r7 to right leg & wiper together). Just a little past half way on pot I was at about 10vdc. I put everything back in place and gave it a check and voila no more sputtering/dropping out. So if you're having issues with your Chinese U-87 clone (theres a few different ones on the market) give this a try. I'm glad I did!
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