Discussion:
Core Sound Announces OctoMic - First 2nd-order Ambisonics Microphone
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Len Moskowitz
2018-03-27 13:59:45 UTC
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core-sound.com/OctoMic/1.php


Len Moskowitz (***@core-sound.com)
Core Sound LLC
www.core-sound.com
Home of TetraMic and OctoMic
Stefan Schreiber
2018-03-27 14:16:20 UTC
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Hi Len,

very interesting, and potentially a major progress in SF recording...

I already have talked about this in private mails, but just to clarify:

Is this a 2h1v mixed order microphone? If not, how do you derive 2nd
order signals?

(What I see are two rings of 4 capsules, shifted 45° against each other.)

Best regards

Stefan

Citando Len Moskowitz <***@optonline.net>:

> core-sound.com/OctoMic/1.php[1]
>
>
>
>
>
> Len Moskowitz (***@core-sound.com)
>
> Core Sound LLC
>
> www.core-sound.com[2]
>
> Home of TetraMic and OctoMic
>
>
>
>
>
> _______________________________________________
>
> Sursound mailing list
>
>
> ***@music.vt.eduhttps://mail.music.vt.edu/mailman/listinfo/sursound[3]
> - unsubscribe here, edit account or options, view archives and so on.



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[2] http://www.core-sound.com
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Ralf R Radermacher
2018-03-27 17:18:37 UTC
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Am 27.03.18 um 15:59 schrieb Len Moskowitz:

> core-sound.com/OctoMic/1.php

They'd better come up with drivers for the products they've already
sold, years ago, e.g. core sound drivers for their useless sorround
headphones.

Ralf

--
Ralf R. Radermacher - Köln/Cologne, Germany
Blog : http://the-real-fotoralf.blogspot.com
Audio : http://aporee.org/maps/projects/fotoralf
Web : http://www.fotoralf.de
Jörn Nettingsmeier
2018-03-27 19:08:54 UTC
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On 03/27/2018 03:59 PM, Len Moskowitz wrote:
> core-sound.com/OctoMic/1.php

Sweet! A resounding "me too" to Stefan's question about the matrix,
since you're one channel short :)
Looking at the geometry, I guess you sacrificed the second-order
rotationally symmetric component (FuMa R or ACN 08), which seems to be a
good choice to me.

What's that disclaimer about third-party PPAs? I mean, your PPA seems to
be an integral part of the mic, given that it produces unbalanced
signals. Is there any other magic going on there?

I wonder if you can get ZOOM to include an octomic firmware in the F8
eventually, as Sennheiser did with their Ambeo mic, that one's mighty
handy. (Not that I'm holding my breath, I wouldn't be surprised if there
were some exclusive deals at play...)

Can I assume that there is an updated version of TetraProc for the
followers of the penguin?

And looking at the shop, I don't see the Rycote lyre listed yet - is it
a generic one that can be had from them, or something custom-made and
not quite ready yet?

I'm trying to come up with a good business case to order one asap, and
since I'm good at fooling myself, it might just happen :-D


All best,


Jörn




--
Jörn Nettingsmeier
Tuinbouwstraat 180, 1097 ZB Amsterdam, Nederland
Tel. +49 177 7937487

Meister für Veranstaltungstechnik (Bühne/Studio), Tonmeister VDT
http://stackingdwarves.net
Eric Benjamin
2018-03-27 19:58:08 UTC
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I’d like to point out that I am the inventor of the second order microphone array called by Core-Sound the Octomic. I published the design six years ago at the 133rd AES Convention in preprint 8728. I purposefully did not patent the invention to allow entrepreneurs to use the design. But I would like a little bit of credit! I realize that Core Sound put in significant effort in making their product.

I made the microphone utilize only eight channels because I only can record eight channels.

Eric Benjamin

From: Jörn Nettingsmeier
Sent: Tuesday, March 27, 2018 12:09 PM
To: ***@music.vt.edu
Subject: Re: [Sursound] Core Sound Announces OctoMic - First 2nd-orderAmbisonics Microphone

On 03/27/2018 03:59 PM, Len Moskowitz wrote:
> core-sound.com/OctoMic/1.php

Sweet! A resounding "me too" to Stefan's question about the matrix,
since you're one channel short :)
Looking at the geometry, I guess you sacrificed the second-order
rotationally symmetric component (FuMa R or ACN 08), which seems to be a
good choice to me.

What's that disclaimer about third-party PPAs? I mean, your PPA seems to
be an integral part of the mic, given that it produces unbalanced
signals. Is there any other magic going on there?

I wonder if you can get ZOOM to include an octomic firmware in the F8
eventually, as Sennheiser did with their Ambeo mic, that one's mighty
handy. (Not that I'm holding my breath, I wouldn't be surprised if there
were some exclusive deals at play...)

Can I assume that there is an updated version of TetraProc for the
followers of the penguin?

And looking at the shop, I don't see the Rycote lyre listed yet - is it
a generic one that can be had from them, or something custom-made and
not quite ready yet?

I'm trying to come up with a good business case to order one asap, and
since I'm good at fooling myself, it might just happen :-D


All best,


Jörn




--
Jörn Nettingsmeier
Tuinbouwstraat 180, 1097 ZB Amsterdam, Nederland
Tel. +49 177 7937487

Meister für Veranstaltungstechnik (Bühne/Studio), Tonmeister VDT
http://stackingdwarves.net
_______________________________________________
Sursound mailing list
***@music.vt.edu
https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe here, edit account or options, view archives and so on.

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Fons Adriaensen
2018-03-27 20:34:15 UTC
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On Tue, Mar 27, 2018 at 12:58:08PM -0700, Eric Benjamin wrote:

> I’d like to point out that I am the inventor of the second order microphone
> array called by Core-Sound the Octomic. I published the design six years
> ago at the 133rd AES Convention in preprint 8728.

That is absolutely true. That preprint is indeed the first published description
and analysis of the capsule geometry as used by the OctoMic.

Ciao,

--
FA
Stefan Schreiber
2018-03-27 20:35:55 UTC
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https://cm-gitlab.stanford.edu/ambisonics/SpHEAR/

"3D models

The 3D models currently include the TinySpHEAR, a four capsule first
order Ambisonics microphone, the Octathingy, an eight capsule second
order design by Eric Benjamin and Aaron Heller and preliminary designs
for 12 and 20 capsule designs (the BigSpHEAR_12 and BigSpHEAR_20
models). The models will be expanded as testing proceeds."

So let's not forget to mention your colleague Aaron (Heller), too?

Best,

Stefan

P.S.: I would see the Octathingy as reduced "Platonic body" design.

This doesn't mean it could not be an invention. Even then the
spherical array microphone has been invented before. The invention
would be to design a microphone for order 1.x?

I am just speculating, because there has to be some specific feature
to be claimed. 

-----------------------------------------

Citando Eric Benjamin <***@pacbell.net>:

> I’d like to point out that I am the inventor of the second order
> microphone array called by Core-Sound the Octomic. I published the
> design six years ago at the 133rd AES Convention in preprint 8728. I
> purposefully did not patent the invention to allow entrepreneurs to
> use the design.  But I would like a little bit of credit! I realize
> that Core Sound put in significant effort in making their product.
>
>
>
> I made the microphone utilize only eight channels because I only
> can record eight channels.
>
>
>
> Eric Benjamin
>
>
>
> From: Jörn Nettingsmeier
>
> Sent: Tuesday, March 27, 2018 12:09 PM
>
> To: ***@music.vt.edu
>
> Subject: Re: [Sursound] Core Sound Announces OctoMic - First
> 2nd-orderAmbisonics Microphone
>
>
>
> On 03/27/2018 03:59 PM, Len Moskowitz wrote:
>
>> core-sound.com/OctoMic/1.php[1]
>
> Sweet! A resounding "me too" to Stefan's question about the matrix,
>
> since you're one channel short :)
>
> Looking at the geometry, I guess you sacrificed the second-order
>
> rotationally symmetric component (FuMa R or ACN 08), which seems to be a
>
> good choice to me.
>
>
>
> What's that disclaimer about third-party PPAs? I mean, your PPA seems to
>
> be an integral part of the mic, given that it produces unbalanced
>
> signals. Is there any other magic going on there?
>
>
>
> I wonder if you can get ZOOM to include an octomic firmware in the F8
>
> eventually, as Sennheiser did with their Ambeo mic, that one's mighty
>
> handy. (Not that I'm holding my breath, I wouldn't be surprised if there
>
> were some exclusive deals at play...)
>
>
>
> Can I assume that there is an updated version of TetraProc for the
>
> followers of the penguin?
>
>
>
> And looking at the shop, I don't see the Rycote lyre listed yet - is it
>
> a generic one that can be had from them, or something custom-made and
>
> not quite ready yet?
>
>
>
> I'm trying to come up with a good business case to order one asap, and
>
> since I'm good at fooling myself, it might just happen :-D
>
>
>
>
>
> All best,
>
>
>
>
>
> Jörn
>
>
>
>
>
>
>
>
>
> --
>
> Jörn Nettingsmeier
>
> Tuinbouwstraat 180, 1097 ZB Amsterdam, Nederland
>
> Tel. +49 177 7937487
>
>
>
> Meister für Veranstaltungstechnik (Bühne/Studio), Tonmeister VDT
>
> http://stackingdwarves.net
>
> _______________________________________________
>
> Sursound mailing list
>
> ***@music.vt.edu
>
> https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe
> here, edit account or options, view archives and so on.
>
>
>
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> Sursound mailing list
>
>
> ***@music.vt.eduhttps://mail.music.vt.edu/mailman/listinfo/sursound[2]
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Fernando Lopez-Lezcano
2018-03-27 20:47:06 UTC
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On 03/27/2018 12:58 PM, Eric Benjamin wrote:
> I’d like to point out that I am the inventor of the second order microphone array called by Core-Sound the Octomic. I published the design six years ago at the 133rd AES Convention in preprint 8728. I purposefully did not patent the invention to allow entrepreneurs to use the design. But I would like a little bit of credit! I realize that Core Sound put in significant effort in making their product.

Yes! And the "Octathingy", which is part of the SpHEAR[*] project, is
also a physical realization of Eric's eight capsule design (thanks and
kudos!).

Two of them are already functional, the first one since 6/2017 (lowres
picture attached), and the current encoder (which is generated Faust
code) outputs WXYZSTUV.

> I made the microphone utilize only eight channels because I only can record eight channels.

That was the attraction of the design for me as well. I have been using
it with a Zoom F8.

Thanks again, Eric!
-- Fernando

[*] https://cm-gitlab.stanford.edu/ambisonics/SpHEAR/


> From: Jörn Nettingsmeier
> Sent: Tuesday, March 27, 2018 12:09 PM
> To: ***@music.vt.edu
> Subject: Re: [Sursound] Core Sound Announces OctoMic - First 2nd-orderAmbisonics Microphone
>
> On 03/27/2018 03:59 PM, Len Moskowitz wrote:
>> core-sound.com/OctoMic/1.php
>
> Sweet! A resounding "me too" to Stefan's question about the matrix,
> since you're one channel short :)
> Looking at the geometry, I guess you sacrificed the second-order
> rotationally symmetric component (FuMa R or ACN 08), which seems to be a
> good choice to me.
>
> What's that disclaimer about third-party PPAs? I mean, your PPA seems to
> be an integral part of the mic, given that it produces unbalanced
> signals. Is there any other magic going on there?
>
> I wonder if you can get ZOOM to include an octomic firmware in the F8
> eventually, as Sennheiser did with their Ambeo mic, that one's mighty
> handy. (Not that I'm holding my breath, I wouldn't be surprised if there
> were some exclusive deals at play...)
>
> Can I assume that there is an updated version of TetraProc for the
> followers of the penguin?
>
> And looking at the shop, I don't see the Rycote lyre listed yet - is it
> a generic one that can be had from them, or something custom-made and
> not quite ready yet?
>
> I'm trying to come up with a good business case to order one asap, and
> since I'm good at fooling myself, it might just happen :-D
>
>
> All best,
>
>
> Jörn
>
>
>
>
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Fons Adriaensen
2018-03-27 20:18:33 UTC
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On Tue, Mar 27, 2018 at 09:08:54PM +0200, Jörn Nettingsmeier wrote:

> Sweet! A resounding "me too" to Stefan's question about the matrix, since
> you're one channel short :)
> Looking at the geometry, I guess you sacrificed the second-order
> rotationally symmetric component (FuMa R or ACN 08), which seems to be a
> good choice to me.

ACN 6 (= R) actually. The only possible choice given this geometry.
The actual R output is derived from W, which is correct for (near)
horizontal sources.
The A/B processing is a combination of IIR filters and an 8 by 8
convolution matrix. The real magic is of course how this matrix
is computed. To know more you'll have to sell your soul :-)

> Can I assume that there is an updated version of TetraProc for the followers
> of the penguin?

See previous post.

> And looking at the shop, I don't see the Rycote lyre listed yet - is it a
> generic one that can be had from them,

AFAIK, yes. They also have one for the Tetramic. I have it, it's quite
effective. Also fits into the wind shield and optional 'dead kitten'.

> I'm trying to come up with a good business case to order one asap, and since
> I'm good at fooling myself, it might just happen :-D

Just let me know if and when :-)

Ciao,

--
FA
Stefan Schreiber
2018-03-27 20:41:23 UTC
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Nice discussion here, interesting for professionals (Fons) and
amateurs (me TOO!) alike.

Sipping some night coffee... 🙂

Stefan

Citando Fons Adriaensen <***@linuxaudio.org>:

> On Tue, Mar 27, 2018 at 09:08:54PM +0200, Jörn Nettingsmeier wrote:
>
>> Sweet! A resounding "me too" to Stefan's question about the matrix, since
>>
>> you're one channel short :)
>>
>> Looking at the geometry, I guess you sacrificed the second-order
>>
>> rotationally symmetric component (FuMa R or ACN 08), which seems to be a
>>
>> good choice to me.
>
> ACN 6 (= R) actually. The only possible choice given this geometry.
>
> The actual R output is derived from W, which is correct for (near)
>
> horizontal sources.
>
> The A/B processing is a combination of IIR filters and an 8 by 8
>
> convolution matrix. The real magic is of course how this matrix
>
> is computed. To know more you'll have to sell your soul :-)
>
>> Can I assume that there is an updated version of TetraProc for the followers
>>
>> of the penguin?
>
> See previous post.
>
>> And looking at the shop, I don't see the Rycote lyre listed yet - is it a
>>
>> generic one that can be had from them,
>
> AFAIK, yes. They also have one for the Tetramic. I have it, it's quite
>
> effective. Also fits into the wind shield and optional 'dead kitten'.
>
>> I'm trying to come up with a good business case to order one asap, and since
>>
>> I'm good at fooling myself, it might just happen :-D
>
> Just let me know if and when :-)
>
>
>
> Ciao,
>
>
>
> --
>
> FA
>
>
>
>
>
>
>
> _______________________________________________
>
> Sursound mailing list
>
>
> ***@music.vt.eduhttps://mail.music.vt.edu/mailman/listinfo/sursound[1]
> - unsubscribe here, edit account or options, view archives and so on.



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Fernando Lopez-Lezcano
2018-03-27 21:05:19 UTC
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On 03/27/2018 01:18 PM, Fons Adriaensen wrote:
> On Tue, Mar 27, 2018 at 09:08:54PM +0200, Jörn Nettingsmeier wrote:
>
>> Sweet! A resounding "me too" to Stefan's question about the matrix, since
>> you're one channel short :)
>> Looking at the geometry, I guess you sacrificed the second-order
>> rotationally symmetric component (FuMa R or ACN 08), which seems to be a
>> good choice to me.
>
> ACN 6 (= R) actually. The only possible choice given this geometry.
> The actual R output is derived from W, which is correct for (near)
> horizontal sources.
> The A/B processing is a combination of IIR filters and an 8 by 8
> convolution matrix. The real magic is of course how this matrix
> is computed. To know more you'll have to sell your soul :-)

Ha ha! I thought I had not done that!!! What I have must be the result
of a (hopefully) short-term rental agreement in the fine print of some
other contract...

I've been slowly working on an A to B encoder for my version of Eric's
eight capsule design (the Octathingy). Simpler than yours, and an
extension of the quad capsule encoder that I initially thought could not
possibly work for the eight capsule design (I get "reasonable" polar
patterns at this point). For now a static A to B matrix (8x8) followed
by FIR filters for each component. The devil is around somewhere (in the
details :-)...

-- Fernando


>> Can I assume that there is an updated version of TetraProc for the followers
>> of the penguin?
>
> See previous post.
>
>> And looking at the shop, I don't see the Rycote lyre listed yet - is it a
>> generic one that can be had from them,
>
> AFAIK, yes. They also have one for the Tetramic. I have it, it's quite
> effective. Also fits into the wind shield and optional 'dead kitten'.
>
>> I'm trying to come up with a good business case to order one asap, and since
>> I'm good at fooling myself, it might just happen :-D
>
> Just let me know if and when :-)
>
> Ciao,
>
Jörn Nettingsmeier
2018-03-28 08:23:31 UTC
Reply
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Raw Message
On 03/27/2018 10:18 PM, Fons Adriaensen wrote:
> On Tue, Mar 27, 2018 at 09:08:54PM +0200, Jörn Nettingsmeier wrote:
>
>> Sweet! A resounding "me too" to Stefan's question about the matrix, since
>> you're one channel short :)
>> Looking at the geometry, I guess you sacrificed the second-order
>> rotationally symmetric component (FuMa R or ACN 08), which seems to be a
>> good choice to me.
>
> ACN 6 (= R) actually.
Ah crap, it's 8 by Jerôme's counting scheme. Still getting bitten by
those after all these years :-D

--
Jörn Nettingsmeier
Tuinbouwstraat 180, 1097 ZB Amsterdam, Nederland
Tel. +49 177 7937487

Meister für Veranstaltungstechnik (Bühne/Studio), Tonmeister VDT
http://stackingdwarves.net
Fernando Lopez-Lezcano
2018-03-31 20:03:42 UTC
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On 03/27/2018 01:18 PM, Fons Adriaensen wrote:
> On Tue, Mar 27, 2018 at 09:08:54PM +0200, Jörn Nettingsmeier wrote:
>
>> Sweet! A resounding "me too" to Stefan's question about the matrix, since
>> you're one channel short :)
>> Looking at the geometry, I guess you sacrificed the second-order
>> rotationally symmetric component (FuMa R or ACN 08), which seems to be a
>> good choice to me.
>
> ACN 6 (= R) actually. The only possible choice given this geometry.
> The actual R output is derived from W, which is correct for (near)
> horizontal sources.

Hey Fons, hmmm... it is better to inject the proper amount of W into R
than to have no R at all? I can see how everything would be (slightly?)
more correct for (near) horizontal sources given the shape of R
(horizontal plane omni), but it would also alias into R anything that
comes from non-(near)horizontal sources. Presumably that does not matter
as much?

-- Fernando

> The A/B processing is a combination of IIR filters and an 8 by 8
> convolution matrix. The real magic is of course how this matrix
> is computed. To know more you'll have to sell your soul :-)
Len Moskowitz
2018-03-27 23:05:10 UTC
Reply
Permalink
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Ambisonic guru Eric Benjamin wrote:

> I'd like to point out that I am the inventor of the second order
> microphone array called by Core-Sound the Octomic. I published the
> design six years ago at the 133rd AES Convention in preprint 8728.

Actually, we're not using Eric's OctaThingy capsule mount design.

We (Fons and I) came up with OctoMic's geometry independently. It has
slightly different angles than Eric's OctoThingy. It's based on a
different geometric solid.

After we designed OctoMic's capsule mount, I happened across Eric's AES
paper, and was pleased that we came up with something that might be as
good.

There are very few great minds in the ambisonic world - Eric is one of
them.


Len Moskowitz (***@core-sound.com)
Core Sound LLC
www.core-sound.com
Home of TetraMic and OctoMic
Stefan Schreiber
2018-03-28 09:47:25 UTC
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Citando Len Moskowitz <***@optonline.net>:

> Ambisonic guru Eric Benjamin wrote:
>
>> I'd like to point out that I am the inventor of the second order
>> microphone array called by Core-Sound the Octomic. I published the
>> design six years ago at the 133rd AES Convention in preprint 8728.
>
> Actually, we're not using Eric's OctaThingy capsule mount design.

https://ccrma.stanford.edu/~nando/publications/sphear.pdf

Fig. 5, second mike

At first sight I could not tell anything about the difference between
an OctaThingy and Octomic capsule mount.

Even not at second...      🤔

Could you give me/us  some hint?

Best,

Stefan

> We (Fons and I) came up with OctoMic's geometry independently. It
> has slightly different angles than Eric's OctoThingy. It's based on
> a different geometric solid.

still not clear...

> After we designed OctoMic's capsule mount, I happened across Eric's
> AES paper, and was pleased that we came up with something that might
> be as good.
>
>
>
> There are very few great minds in the ambisonic world - Eric is one of them.
>
>
>
>
>
> Len Moskowitz (***@core-sound.com)
>
> Core Sound LLC
>
> www.core-sound.com[1]
>
> Home of TetraMic and OctoMic
>
>
>
> _______________________________________________
>
> Sursound mailing list
>
>
> ***@music.vt.eduhttps://mail.music.vt.edu/mailman/listinfo/sursound[2]
> - unsubscribe here, edit account or options, view archives and so on.



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Len Moskowitz
2018-03-28 11:23:15 UTC
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Stefan Schreiber wrote:

> At first sight I could not tell anything about the difference between
> an OctaThingy and Octomic capsule mount.


> Even not at second...      


>
> Could you give me/us  some hint?
Eric's OctaThingy is based on a tetragonal trapezohedron.
OctoMic is not. It's based on another geometric solid. The angles are
different.

Len Moskowitz (***@core-sound.com)
Core Sound LLC
www.core-sound.com
Home of TetraMic and OctoMic
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umashankar manthravadi
2018-03-28 14:06:11 UTC
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I was showing off a second order brahma microphone at the AES los angeles in 2016, I had two versions (I think I took only one) one is a standard octagon, the other was an octagon with the top half rotated 45 degrees, which looks remarkably like Eric Benjamin’s Octathingy. Both used 14 mm capsules. I have since built two other designs. One is a tetrahedron surround by a ring of four, and the other similar, but the ring is tangential capsules. I will probably end up using only the octathingy style. But in the meantime, I have been seduced by all digital MEMs based second order microphone outputting directly to USB. MEMs are Omni, so I am flush mounting them on a polished acrylic sphere 1.5 cm radius. I will post photographs on my facebook Brahma page soon.



By the way I visualize the octathingy as two tetrahedron superposed, one rotated 180 degrees.



umashankar







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________________________________
From: Sursound <sursound-***@music.vt.edu> on behalf of Len Moskowitz <***@optonline.net>
Sent: Wednesday, March 28, 2018 4:53:15 PM
To: Stefan Schreiber
Cc: Sursound List
Subject: Re: [Sursound] Core Sound Announces OctoMic - First 2nd-orderAmbisonics Microphone

Stefan Schreiber wrote:

> At first sight I could not tell anything about the difference between
> an OctaThingy and Octomic capsule mount.


> Even not at second...


>
> Could you give me/us some hint?
Eric's OctaThingy is based on a tetragonal trapezohedron.
OctoMic is not. It's based on another geometric solid. The angles are
different.

Len Moskowitz (***@core-sound.com)
Core Sound LLC
www.core-sound.com<http://www.core-sound.com>
Home of TetraMic and OctoMic
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Fernando Lopez-Lezcano
2018-03-28 23:27:32 UTC
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On 03/28/2018 04:23 AM, Len Moskowitz wrote:
> Stefan Schreiber wrote:
>
>> At first sight I could not tell anything about the difference between
>> an OctaThingy and Octomic capsule mount.
>
>> Even not at second...
>>
>> Could you give me/us some hint?
>
> Eric's OctaThingy is based on a tetragonal trapezohedron.
> OctoMic is not. It's based on another geometric solid.

Which one exactly?

> The angles are different.

I presume you mean the elevation angles, right? I don't think Eric's
paper includes the actual elevation angle he used for his design. What
is the elevation angle in the Octomic?

Aaron (Heller) did 3D print some Octathingy arrays and his code
(https://bitbucket.org/ajheller/mic-arrays/, predates mine) uses
atan(sqrt(1/2)) for the elevation (same as a tetrahedral microphone).

Eric writes that the design is based on the tetragonal trapezohedron,
but I always found it easier to visualize it using its dual, the square
antiprism (with the capsules mounted in its vertices):

https://en.wikipedia.org/wiki/Square_antiprism

Changing the side triangles from equilateral to isosceles (ie:
stretching it vertically) creates a family of shapes, most interesting
among them would be the equilateral square antiprism (equal angles
between capsules) and the one where the vertical elevation angles match
the ones of a tetrahedral design. I always had both choices in my 3d
models, but others are possible. Different vertical elevation angles
will optimize the array differently, but the underlying geometric solid
is the same.

-- Fernando

PS: I first asked about what could be done with eight capsules in July 2015:

On 07/24/2015 09:34 AM, Aaron Heller wrote:
> If you want to try something, there's what we've been calling "the octathingy". Four capsules up, four down, with the down facing ones rotated 45 degrees. See attached photos.

I 3d printed my first "proof of concept" in November 2015 (see picture)
but it took a long time to get a full working prototype (I did the
tetrahedral design first). Always working on too many projects... :-)
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Len Moskowitz
2018-03-27 23:10:21 UTC
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Ralf R Radermacher wrote:

> They'd better come up with drivers for the products they've already
> sold, years ago, e.g. core sound drivers for their useless sorround
> headphones.

Core Sound LLC has never, ever sold surround headphones - nor headphones
of any kind - so I don't know what you're referring to.

Perhaps you're thinking of a "core audio" software driver for another
manufacturer's product? Core Sound LLC is not related in any way to
"core audio" drivers.


Len Moskowitz (***@core-sound.com)
Core Sound LLC
www.core-sound.com
Home of TetraMic and OctoMic
Len Moskowitz
2018-03-27 23:29:33 UTC
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J?rn Nettingsmeier wrote:

> Sweet! A resounding "me too" to Stefan's question about the
> matrix,since you're one channel short :)

OctoMic is a 2h1v microphone. The channel that's compensated for in
OctoMic's 2nd-order B-format is R. It's *not* missing.

And of course, the 1st-order vertical channel is still present.

> What's that disclaimer about third-party PPAs? I mean, your PPA seems
> to be an integral part of the mic, given that it produces unbalanced
> signals. Is there any other magic going on there?

It's a very competitive world, so please forgive me if I don't answer
you.

> I wonder if you can get ZOOM to include an octomic firmware in the F8
> eventually, as Sennheiser did with their Ambeo mic, that one's mighty
> handy.

Sennheiser uses a single generic encoder for all of their 1st-order
microphones. That allows Zoom to easily do the A- to B-format for all
Sennheiser microphones.

From our perspective, that's not a great idea, because microphones and
capsules age - they are different even straight from the factory - and
there's currently no way to compensate for aging drift in Sennheiser's
product.

From the start, we allow for differences between microphones by
individually measuring each TetraMic and OctoMic; we provide a unique
calibration file for each microphone.

Of course, as a Sennheiser microphone ages and drifts, you could send it
to us for measurement and calibration. We'd measure it and return it
with its calibration file. From then on you'd use the encoders
recommended for TetraMic.

We recommend re-calibration every three years for 1st-order microphones
used for general applications, and every two years for those used for
acoustic measurement applications.

> Can I assume that there is an updated version of TetraProc for the
> followers of the penguin?

Yes. Fons commented on this in the last Sursound Digest.

> And looking at the shop, I don't see the Rycote lyre listed yet - is
> it a generic one that can be had from them, or something custom-made
> and not quite ready yet?

It's a common Rycote product: the INV-7. You can use it with either the
the standard black 72 Shore lyres or the red 62 Shore lyres. It's
available from Rycote retailers.


Len Moskowitz (***@core-sound.com)
Core Sound LLC
www.core-sound.com
Home of TetraMic and OctoMic
David Pickett
2018-03-28 05:27:29 UTC
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Len,

In addition to the Zoom 8-track recorder that is mentioned on your
website, I would recommend the similarly priced Roland R-88, which
has the significant advantage that the controls are easier to adjust
for those of us with large hands!

David

At 15:59 27-03-18, Len Moskowitz wrote:
>core-sound.com/OctoMic/1.php
>
>
>Len Moskowitz (***@core-sound.com)
>Core Sound LLC
>www.core-sound.com
>Home of TetraMic and OctoMic
>
>
>_______________________________________________
>Sursound mailing list
>***@music.vt.edu
>https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe
>here, edit account or options, view archives and so on.
Len Moskowitz
2018-03-28 11:44:19 UTC
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David Pickett wrote:

> In addition to the Zoom 8-track recorder that is mentioned on your
> website, I would recommend the similarly priced Roland R-88, which has
> the significant advantage that the controls are easier to adjust for
> those of us with large hands!

We haven't had any reports from our customers on the Roland R-88, so we
didn't include it. We're in the same situation with SonoSax's eight
channel recorder setup.

The Zoom F8 and Sound Devices MixPre-10T offer modern pre-amp design and
the ability to gang the eight trims.

We also recommend that levels between channels be matched to within 0.1
dB.

Does the R-88 offer those features? The older R-44 did not.


Len Moskowitz (***@core-sound.com)
Core Sound LLC
www.core-sound.com
Home of TetraMic and OctoMic
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