On Thu, 1 May 2008 12:42:39 -0700, dpierce.cartchunk.org@[EMAIL PROTECTED]
wrote
(in article
<0c11a533-2d26-424b-a2b0-a25ab645473a@[EMAIL PROTECTED]
>):
> On May 1, 2:59 pm, Beta Zero <beta_z...@[EMAIL PROTECTED]
> wrote:
>> In the olden days, microphones had membranous
>> diaphragms of some kind, and the way these things
>> responded to vibrations, had a lot to do with
>> the frequencies transmitted. I figured that a 'hot'
>> microphone would produce a different range of
>> sounds than a 'cold' one.
>
> Uh, no.
>
> The vibrations impinging on the diaphragm produce
> corresponding eletrical signals. 1 kHz in, 1 kHz out,
> simple as that.
>
> If "a hot microphone produce a different range of
> sounds than a cold one," you have a seriously broken
> microphone: throw it out.
>
> Microphone sensitivity, noise level and even relibility
> can change with temperatire, but there's no physical
> mechanism, which can cause an operating microphone
> listening to one range of frequencies to change them
> into some other range.
>
I think he means that a heated diaphragm might have different frequency
response characteristics than would one at normal room temperature. For
instance, the diaphragm material might expand when warm making it more
flexible. This could alter the fundamental resonance of the diaphragm
making
either more or less sensitive to frequency extremes. Bottom end might
improve
at the expense of the top, or, it might bring the resonant peak down in
frequency from perhaps 16 - 17 KHz to around 12 Khz causing a hump there.
After all, most modern condenser microphone diaphragms are made of Mylar
with
a metallic (usually gold) film sputtered on to it. Mylar definitely gets
soft
and expands when warmed.
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