[AMRadio] Microphone recomendation


Jim Tonne tonne at comcast.net
Tue Sep 22 11:07:19 EDT 2009


I have been lurking here and reading the discussion
which seems to me to have reduced itself down to a
kind of "my daddy is better than your daddy" kind of
thing.

The person who said the D104 microphone could be
thought of as a voltage generator in series with a
500 pF capacitor hit the nail on the head!  Exactly
correct (although I thought it might be a  *slightly*
higher capacitance value).

I have spent a few minutes with LTspice and made
a plot which clearly shows what happens when you
change the value of the load on the D104 microphone.
With a 10 megohm load the -3 dB point will be right
at 30 Hz.  

Please, fellows, take a quick peek at this plot:
http://tonnesoftware.com/appnotes/D104loadTest.gif

The bottom line of this note is that going higher than
10 megohms for a load is nonsense.   Pure nonsense.

- Jim W4ENE




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