Highpitched whining noise; how to get rid of it?

For the technically minded, some good reads and worth bookmarking....

Scroll down to just a bit over half way down the page linked below to "Hum, Buzz, and RF Interference -- Written for Audio Professionals"
Audio Systems Group, Inc. Publications

Under the heading "AES Papers", this article covers a lot of ground....
http://audiosystemsgroup.com/AES-RFMicrophonesASGWeb.pdf

A few of the microphone articles suggest the importance and methods of the pin 1 grounding, which from the the OP's 'fix' of the problem with a new cable may have been a compromised ground or shield connection in the original cable.
 
Thanks Mark. I have had a skim through the AES paper and will If I may, summarise some conclusions?

The RF problem seems in part to be due to poor bonding (at RF) between the microphone body and the incoming shield on pin 1.

Tying P1 to the XLR plug shell MIGHT effect an improvement but that gives you a non-standard cable* that might cause other problems in other situations.

Tying P1 to shell AT RF with a capacitor (or special XLR connectors) is often effective and does not compromise the cable.

Putting an "RF Impedance" in the cable can be very effective. Ferrite rings are of course made for this very purpose but mic cable tends to be of large OD (C 6.5mm) and in any case the plugs are a problem.
One solution is to make up male to female 'slugs'. These are lengths of small, ~4mm mic cables, pref' foil shielded. Sans plugs, several turns can be put on a ferrite ring and the slug inserted at the mic end or pre amp end, whichever is best. Some serious infestations might need one at BOTH ends!

The above emphasises the fact that not ALL audio problems can be solved with ready made, off the shelf devices so, LEARN some electricals you recording wannbees!

I noticed smugly that the microphnes were unfailingly referred to as "Capacitor" microphones!

*But, sometimes RFI stopping measures result in an ad hoc, non standard, even sub optimal audio performance system. Such is life!

Dave.
 
There's also the Rane papers:

Rane Library

Enjoy them while it lasts, as Rane has been taken over by some large entity. Sorry, forgot the name. It's not Harman, for once.
 
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