and how to match microphone impedance?
Right, helmets good idea. So along the way I bought a second David Clark headset (ebay) for pax comm. And, lo and behold, nobody had ever mentioned that mixing mike impedances would yank the rug out from under my intercom!
Clearly I now have one hi-imp (600 ohms?) and one lo-imp (8?) mike. Switching to hot mike (=parallel ON) results in losing the audio when both are on line; evidently the low-imp absorbs all energy from hi-imp and defeats the input circuit?
Caveat emptor! But how do you LOOK at the mike and learn whether it's high or low? Who's in charge? D Clark doesn't explain a word of this in the brochure comes with headset.
Is there a simple fix? Interchangeable mikes? Which is better to settle on?
(This is a stock, so far as I know, RHC 1991 R22 intercom wiring, no special additions, standard factory switches.)