Well,

Having thumbed through the articles on the other news group (Some 300
of them), I'm almost certain that this problem is with his equipment,
the grounding and shielding of that ribbon microphone and associated
preamp and is likely to originate with some kind of local
unintentional radiator located within his house (A switching power
supply, plasma TV, Cable tuner etc.) Listening to the audio provided
really makes me think there is some very noisy switching power supply
in this mix somewhere.

I would start by verifying that the shield on that "special" 7 pin
cable between the preamp and the mic is not damaged and I would invest
in some of the clip on RFI cores that you can loop the microphone
cable though a few times as close to the preamp as possible. He needs
to be 100% sure that he has eliminated all the possible grounding
problems (which it seems that he has a number based upon his posts) by
lifting power and signal grounds where necessary to make sure there is
only ONE path to ground from ANY piece of equipment.

In the end, I'll bet that it's the microphone/preamp that is to blame
and getting that fixed can be something way beyond the scope of what
can be discussed on Usenet effectively.

-= Bob =-

On Sep 17, 9:24 am, "Richard Crowley" wrote:
I've been following a conversation over on news:rec.audio.pro
originated by a guy who is getting what appears to be CW
RFI on his microphone(s) at 9 KHz. He also reported hearing
similar "whistling" on the AM BCB.