--- In Scott Fraser
<> wrote:
>
> To amplify and clarify a bit on this:
>
> <<There are many ways to obtain stereo, one way is to use two
> microphones with the same pickup pattern.
> These can be either omni or cardioid microphones.>>
>
> They can be any of a number of other patterns as well,
hypercardioid,
> subcardioid, & figure eight being common.
>
> <<Omni's can be used 'spaced' or with some barrier
> between them.>>
>
> Also known as "AB" stereo, with "near-spaced" & "wide-spaced"
being
> the principle variations on the theme.
>
> << While cardioids are often used in a
> 'crossed pair' configuration sometimes referred to as
> 'coincident pairs'.>>
>
> The "near-coincident" approach is increasingly popular, as it
> incorporates time-of-arrival information as well as amplitude
> differentiation between channels. Coincident miking makes use only
of
> amplitude information for directional cues. Near coincident places
> the mics at approximately the distance between human ears, & is
> typified by the ORTF & NOS standards. Any number of hybrid
techniques
> between coincident & near coincident are also valid, depending on
the
> width of the intended stereo field & the distance to the intended
> subject.
>
> <<The other method for recording stereo is where you use
> two microphones with very different polar diagrams, MS
> stereo. This is where a figure of 8 and an omni
> microphone are used.>>
>
> Generally cardioid is used as the mid microphone in MS technique,
> although hypercardioid also is used. With a cardioid mic the
decoded
> MS output is identical to the output of an XY coincident pair, so
MS
> is really just a subset of the coincident approach.
>From the Sound Devices web site.
M =3D Mid (Middle, Main)
The choice of mid signal microphone is arguably more critical than
the selection of side microphone. The mid-signal microphone is often
a flat-frequency-response cardioid {=F1 =3D a(1 + cos =E8)}, but can be
nearly any polar pattern, including hyper-cardioid, super-cardioid,
line-gradient (shotgun) or omni-directional. Because of the inherent
mono compatibility of MS stereo, when an MS stereo signal is folded
to mono, only the Mid microphone signal remains.
http://www.sounddevices.com/tech/ms_stereo.htm
>
> <<Finally there is the single point stereo mic something
> like the Shure VP88 which I know some people use.>>
>
> The Shure VP88 is an MS array. Various other stereo mics provide
XY,
> almost XY & Blumlein configurations in a single point body.
>
> Scott Fraser
>
>
>
>
>
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