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From: wexfordpress on 20 Nov 2009 09:30
For use with the microphone jack on the front of my computer, should I
use a high impedance (600 ohm) microphone or a low impedance (8 ohm)
mike?

John Culleton
From: cassiope on 20 Nov 2009 11:04
On Nov 20, 6:30 am, wexfordpress <j...(a)wexfordpress.com> wrote:
> For use with the microphone jack on the front of my computer, should I
> use a high impedance (600 ohm) microphone or a low impedance (8 ohm)
> mike?
>
> John Culleton

Unfortunately it is fairly likely that neither will work properly
without some electronic
"assistance". Most audio cards are set up for higher-impedance
microphone which
have a higher voltage level output.

There are some simple 1- or 2-transistor circuits posted on the
internet that show
how you can adapt 600 ohm microphone to audio card inputs. I did
something
similar for a microphone for my son. It was pretty easy, and readily
incorporated
into the body of the microphone. [disclaimer: I'm an EE]

HTH...
From: Michael Black on 20 Nov 2009 12:05
On Fri, 20 Nov 2009, wexfordpress wrote:

> For use with the microphone jack on the front of my computer, should I
> use a high impedance (600 ohm) microphone or a low impedance (8 ohm)
> mike?
>
> John Culleton
>
600ohm is low impedance. High impedance would be crystal or ceramic
microphones, with impedance in the tens of thousands of ohms.

The only time you'd see microphones at the 8ohm level is when someone
used a speaker as a microphone.

Any "computer microphone" is going to be a dynamic microphone (about taht
600ohm impedance) or an electret that will be higher. Since you can buy
either type for use with computers, it shouldn't matter.

PIcking a good microphone, ie a "good" microphone intended for some other
use, then other microphones come into play.

One would have to check the input impedance of a sound card, I suspect
they'd keep it relatively high, because it's easy and it allows for a
variety of microphones.

A low impedance microphone feeding a high impedance input isn't likely to
be a real problem. But feeding a high impedance microphone into a low
impedance input may attenuate the signal too much, and may load down
the microphone so much that frequency response is diminished.

Michael

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