if the capsules are near enough, the phase errors are no worse than they wo=
uld be with a large capsule. for me the advantage of paralleled capsules wa=
s that the fets are paralleled too. there is a three db improvement with a =
pair of capsules and six db with four, which improves s/n substantially.
my arrays are mounted on a plate about six inches or less across with the c=
apsules in an irregular cross. there is a central capsule, the second capsu=
le is half inch away, the third is at 90 degrees and one inch away, etc. th=
e plate essentially turns the capsules into boundary microphones, with a si=
x db gain over free field and a hemispherical pattern. the array improves b=
oth s/n and directionality with a small loss in fidelity. (I have recorded =
music with these plate arrays!)
=A0
umashankar
>________________________________
> From: Robin <>
>To:
>Sent: Monday, March 4, 2013 7:09 PM
>Subject: [Nature Recordists] Re: Is my equipment outdated?
>
>David wrote:
>
>> I'm not sure how connecting two mics will help. If they are outputting
>> identical signals, a parallel connection will only affect the
>> impedance matching, but if the outputs are not identical, they will
>> interfere, especially at higher frequencies. I would expect to hear
>> "flanging" or "comb filter" effects.
>
>I will make some assumptions about the theory and someone else can tell me=
I am wrong! If the mic caps carry the same signal (input sound waves entir=
ely coincident) one would get a consistent 3dB boost in signal but the self=
-noise (being stochastic) would not sum. Phase effects only enter at freque=
ncies high enough that they don't significantly compromise the sound. Havin=
g multiple caps per channel averages out the different responses in each in=
dividual cap, resulting in greater consistency between Left and Right.
>
>In any case Vicki Powys has successfully used 2 caps per channel on a SASS=
array. Her recordings sound fine to me.
>
>And IIRC, umashankar has run five or more caps in parallel to form a direc=
tional array.
>
>Maybe these builders will contribute on this issue.
>
>:: Robin Parmar :: remanence.robinparmar.com ::
>
>
>
>------------------------------------
>
>"While a picture is worth a thousand words, a
>sound is worth a thousand pictures." R. Murray Schafer via Bernie Krause.
>
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