Hey, Jerry Lee,
my namens Ralf and this is the first reply ?in this forum. I¡® m writing from Germany so please ? ? excuse my bad language.
About 10 years ago I made a very similar experiment wich I stopped as I got me a lath to work with. I found out the same things that you posted here and came to the following conclusions:
1- It is important to get the membrahn streched the same degree to all sides?
2- the backplate cannot be stiff enough. That is one reason for partial cancelation of higher frequencies. This is because if it is not it will probably cancel out frequencies by slightly moving by soundpressure in the opposit direction of the membrahne.
3- the backplate had to be fairly thick so that you can make some sackholes in it for damping ?reasons?
4- to get rid of most of the parasitic capacitance, you simply should take of the copper of your backplate piece in the airia where the frame that holds your membrahn will be positioned?
I hope that this will bring you in a good direction.
Good luck?
I'm pretty suspicious of the membrane resistance which is a few
ohms per cm2 as the culprit. So any suggestions for more
conductive aluminiumised Mylar would be greatly appreciated!
Whatever few ohms there don't matter compared to the Gigaohm input
resistance of the Alice circuit.
Look elsewhere. Surely 20 micron thickness does not help with
sensitivity, but all the parasitic capacitances are probably the
main culprit.
