I am going to attempt to build a panel condenser microphone (a large, flat mic about 1/2 foot by 1 foot that picks up everything on a theatrical stage), and I do not know which metal to use for the backplate (aluminum foil is pretty much my only option for the diaphragm, unless anyone can think of anything better that I would still have easy access to). I can get an array of sheet metals; steel, aluminum, brass, copper, but I don‘t whether to use something more conductive or more insulative (I‘m guessing the former). Any suggestions?
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For the backplate it shouldn't matter much. I think I might use aluminum as it is east to work with and light. Another possibility would be an un-etched copper clad circuit board which would have the relatively flat, rigid and stable epoxy-fiberglass board for support and the copper foil for conductivity. I'm not sure if the conductivity would be enough, but you might try aluminized mylar for the diaphragm. If you can find the very thin aluminized mylar it will heat shrink to some extent which may help getting a smooth taut surface.
