A detailed explanation would be a spherical harmonic one
... and possibly not what you want ...
A simplistic one is that 'W' is a sum, whereas 'X', 'Y', 'Z' are
differences.
So (ignoring any misgivings about using six capsules, and
presuming their directional sensitivities are such that this
will work, ....):
W = Xf + Xb + Yl + Yr
X = Xf - Xb
Y = Yl - Yr
(I am also ignoring normalisation, and dropping 'Z' to keep
it simple.)
( f,b,l,r = front, back, left, right)
So to feed a 'front' loudspeaker:
F = W + X
and a 'back'
B = W -X
or
F = 2Xf + Yl + Yr
B = 2Xb + Yl + Yr
This is hideously over-simplified, but with all its errors
I hope it demonstrates how using a sum (W) and
differences (X,Y,..) allows reconstitution.
For a better (accurate) appreciation, you need to tackle spherical
harmonics.
Michael
------------------------------
Message: 3
Date: Thu, 24 May 2012 12:53:10 +0200
From: J?rn Nettingsmeier <[email protected]>
Subject: Re: [Sursound] Why do you invert the phase of one channel of
multi capsule microphones ?
To: Surround Sound discussion group <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 05/24/2012 11:57 AM, Augustine Leudar wrote:
Hello all,
I am building a six capsule ambisonic microphone. I have been told
that with the opposite capsules (ie up/down, left/right,
forward/backwards) I should invert the phase of one of the channels
and then add them to get the X,Y,Z for the ambisonic b format. I've
been struggling to find a good explanation - I was wondering if
anyone could explain why this is in detail ?
if this is not obvious to you, then i'd recommend to do some more
research before you spend lots of money on parts and lots of time on
assembling the mike.
what you are trying to do sounds like a "native" b-format microphone,
but made from individual cardioid capsules. to get a figure-of-eight
(which has one in-phase lobe and another with inverted polarity), you
can subtract two back-to-back cardioids, which is just the same as
adding them with one of the capsules inverted.
best,
j?rn
--
J?rn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487
Meister f?r Veranstaltungstechnik (B?hne/Studio)
Tonmeister VDT
http://stackingdwarves.net
------------------------------
Message: 4
Date: Thu, 24 May 2012 16:43:10 +0530
From: umashankar mantravadi <[email protected]>
Subject: Re: [Sursound] Why do you invert the phase of one channel of
multi capsule microphones ?
To: <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
dear augustine
x y and z represent three figure of eight microphones. the way to generate
a figure of eight microphone out of two opposed cardioids is to invert the
phase of one, and sum them.
umashankar
i have published my poems. read (or buy) at
http://stores.lulu.com/umashankar
Date: Thu, 24 May 2012 10:57:35 +0100
From: [email protected]
To: [email protected]
Subject: [Sursound] Why do you invert the phase of one channel of multi
capsule microphones ?
Hello all,
I am building a six capsule ambisonic microphone. I have been told
that with the opposite capsules (ie up/down, left/right,
forward/backwards) I should invert the phase of one of the channels
and then add them to get the X,Y,Z for the ambisonic b format. I've
been struggling to find a good explanation - I was wondering if
anyone could explain why this is in detail ?
_______________________________________________
Sursound mailing list
[email protected]
https://mail.music.vt.edu/mailman/listinfo/sursound
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Message: 5
Date: Thu, 24 May 2012 07:48:02 -0500
From: "Michael Graves" <[email protected]>
Subject: [Sursound] Dev-Audio MicroCone
To: "Surround Sound discussion group" <[email protected]>
Message-ID:
<[email protected]>
Content-Type: text/plain; charset="iso-8859-1"
Hello All,
I'm delurking for a moment to see if anyone here has any knowledge of
Dev-Audio's Microcone?
http://www.dev-audio.com/
They have some marketing language that describes it as a 3D microphone
for simple recording applications. It records four streams to their
recording application (Mac only.)
They seem to have six capsules internall, but record four streams.
Could it be derived from something Ambisonics based?
I've emailed them to inquire about the specifics of the microphone
capsules.
Michael
--
Michael Graves
mgraves<at>mstvp.com
http://www.mgraves.org
o713-861-4005
c713-201-1262
sip:[email protected]
skype mjgraves
Twitter mjgraves
------------------------------
Message: 6
Date: Thu, 24 May 2012 14:27:26 +0100
From: "Rev Tony Newnham" <[email protected]>
Subject: Re: [Sursound] Dev-Audio MicroCone
To: "'Surround Sound discussion group'" <[email protected]>
Message-ID: <[email protected]>
Content-Type: text/plain; charset="us-ascii"
Hi
The specs on http://www.dev-audio.com/products/microcone/ show that the
device appears to use 7 omni-capsules and some sort of "custom" DSP to
obtain the requisite 6 channels (for group discussions) from them.
They're mraketting it for voice recording.
Every Blessing
Tony
-----Original Message-----
From: [email protected] [mailto:
[email protected]]
On
Behalf Of Michael Graves
Sent: 24 May 2012 13:48
To: Surround Sound discussion group
Subject: [Sursound] Dev-Audio MicroCone
Hello All,
I'm delurking for a moment to see if anyone here has any knowledge of
Dev-
Audio's Microcone?
http://www.dev-audio.com/
------------------------------
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End of Sursound Digest, Vol 46, Issue 6
***************************************
