[NewMusic] Core Sound ambisonic mics

[Matt J. Ingalls]

barry:
tom is right. soundfield mic is 4 cartiods in a tetrahedron (a-format), 
which is full 3-D. output is usually transcoded (simple add&subtract)
to b-format which is 
the omni+3 bi-directional (WXYZ) you are talking about.
and i believe this is "1st order" whereas "2nd+ order" is more channels 
added to that..

-m

On Wed, 7 Nov 2007, barry threw wrote:

> You actually need 3 *bi-directional* mics and one omni, and they are
> as close to coincident as possible (without fancy delay processing).
> But, that is only for 3rd order (preserving height information).
>
> For second order you can need 2 bi and one omni; that will give you
> accurate recording of a 2D sound field.
>
> For stereo, all you need is one bi and one omni.  But thats M/S (kind
> of) and we all knew about it.
>
> b
>
> On Nov 7, 2007, at 9:45 AM, Tom Duff wrote:
>
>>
>> Just noticed this for recording weenies:
>>
>> http://www.core-sound.com/TetraMic/1.php
>>
>> It's an ambisonic transducer (tetrahedral coincident array of cardioid
>> mics) for under $1000.  Looks great.  Len Moskowitz (Core Sound)
>> usually
>> makes first-rate stuff for the price.
>>
>> Ambisonic recording is extremely cool.  By using 4 directional mics
>> evenly
>> spaced in 3-D, you can, by appropriate mixing, simulate arbitrary
>> coincident microphone arrays.  If you use a 4-channel recorder, you
>> can
>> even change miking decisions after the fact.
>>
>> --
>> Tom Duff.  Hwanon ferigeath ge faette scyldas?
>> _______________________________________________
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>
> Barry Threw
> Media Art and Technology
>
>
> San Francisco, CA	Work: 857-544-3967
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>
>
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