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Re: match that impedance

Subject: Re: match that impedance
From: "oryoki2000 <>" <>
Date: Fri, 17 Jan 2003 18:18:22 -0000
My understanding of impedance matching (and the
physics of electricity in general) is pretty
poor.  Here's what I think is happening.

By reducing the difference in impedance between
mic and recorder, the amount of power (energy
per unit time) received by the recorder is
increased.  This gives the recorder pre-amp
a stronger signal, and results in a louder
recording without requiring the pre-amp to add
gain.  Since consumer minidisc pre-amps are
pretty poor, getting a stronger signal is
a good thing -- up to a point.

The reason a low impedance mic is usually attached 
to a medium impedance recorder input is to 
reduce the likelihood that the mic will over-drive 
the recorder pre-amp, thus distorting the recording.  
So by reducing the difference in impedance, you're 
increasing the chance that the mic signal will be 
too powerful.

In nature recording, the issue most commonly 
encountered is too weak a signal, not too strong.
That's why we're always trying to get the mic
closer to the subject.  So the risk of impedance
matching can be worth the reward.  Just keep
an eye on the meters on your recorder!

And if you find yourself in a situation where 
the mic signal is too hot (you're unexpectedly
surrounded by howler monkeys and bellbirds, for
example), it's a simple matter to unplug the 
impedance matching circuit from the mic input
and return to recording.  

As I said in my original post, people should
give the impedance matching cable a try with 
their consumer grade minidisc and see if it helps.
It works for me.

--oryoki



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