I get a "corrupted file" when I try to unzip it.

Why can't you post a .pdf?

 

Here it is.
When I was going to the folder where the pdf file is, I could not see the file in the folder pop-up window. But when I typed the name of the pdf file, I succeeded to upload the file.

 

The project: Installing a microphone system inside an accordion using a number of electret condenser microphones (ECMs). I have seen several commercial applications. They invariably use 3 to 10 (!) ECMs for the treble (right hand) part of the accordion and 1 to 3 ECMs for the bass (left hand) part of the instrument. I'm thinking of using 4 microphone capsules for the treble and 2 for the bass.
My question regards the way the capsules are to be paralleled. Since I have not found a reliable source of information on the Internet to this issue, I have thought of two ways of implementing this: either paralleling all capsules together on each side with a common current limiting resistor and a common output capacitor or (more complicated solution) supplying each capsule with its own current limiting resistor and paralleling all outputs.
A mini op-amp based preamplifier will be installed inside the accordion, together with the battery power supply, or the preamp will be housed in an external box.
Any help is greatly appreciated.
Evangelos

Electret mics parallel nicely with no special requirements. A common bias resistor and cap work fine. Mems don't work as well. The electrets are constant current, the mems are constant voltage (almost).

 

This thread is 5 years old.

In any case, I would supply each mic with its own bias resistor.
Then I would sum the output of each mic via individual C and R in series to a common node.