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Re: 722 vs [was] NT1-A and moisture

Subject: Re: 722 vs [was] NT1-A and moisture
From: Mike Feldman <>
Date: Tue, 21 Jun 2005 20:16:06 -0500
I'm here to pick technical nits ... I have neither Senn MKH mics nor Rode m=
I do have an Edirol R-1, and a SD 722 on order.

Klas Strandberg wrote:

> 2/ Electrets (which also are condensor mic's!) are less sensitive, mainly=

> because there is no polarizing voltage applied on the membrane.

Actually, there is a polarizing voltage with respect to the backplate.
It's just from a permanently trapped charge in the backplate, and not
a voltage from an external source.

> 3/ MKH line is something else: There is no polarizing voltage, neither is=

> there an extreme input impedance. Instead, the membrane/electrode
> configuration is just a variable resistor which determines the frequency =
> an oscillator...

This is wrong.  The diaphragm is *not* a variable resistor.  It's a variabl=
capacitor just like any other condensor mic.  And there is a polarizing vol=
it's just that it's AC (and RF frequency AC, at that).  So the average
polarizing voltage is zero, but the RMS voltage is non-zero.  But yes, the
diaphragm movement does change the frequency of a resonant circuit.

-- Mike Feldman


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