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Re: AT822 Microphone Noise Floor

Subject: Re: AT822 Microphone Noise Floor
From: Walter Knapp <>
Date: Fri, 02 Aug 2002 22:30:59 -0400
Dan Dugan wrote:

> >  > I suspect frequency response characteristics under low amplitude is
> >>  what leads people to talk about a mic's "reach" of far sounds
> >  > relative to near sounds.
> 
> I think directivity and sensitivity/noise characteristics are what
> makes the difference.

Directivity is not a large component if any. This is one of the points
about a shotgun mic, it's directivity is much better than a regular mic,
but it's reach is not much different. It cuts off the side noise, but
does not provide extra gain for the center.

Reach is kind of like gain, but includes all the mic system, including
any noise produced by the system. So a parabolic has gain from it's
reflector, and a PZM from the boundary, both occur before reaching the
mic. Those two are gain that's free from a increase in mic noise,
whereas the mic noise and sensitivity are fixed and linked for any given
design. If you try and get gain by amplifying the mic output, you
amplify the mic noise, so there is a definite limit to how much
amplification you can apply. If dealing with a very low noise mic, you
may be able to pick up some usable gain via amplification. If you do so,
then you would talk about the reach of the combo.

Reach is not a frequency thing, as it's usually in terms of picking up a
specific species, which is a fairly limited frequency range.

Walt



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