Re: [Sursound] Core Sound Announces OctoMic - First 2nd-orderAmbisonics Microphone

[Fernando Lopez-Lezcano]

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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Re: [Sursound] Core Sound Announces OctoMic - First 2nd-orderAmbisonics Microphone

[umashankar manthravadi]

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







Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10




From: Sursound <sursound-boun...@music.vt.edu> on behalf of Len Moskowitz 
<lenmoskow...@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 (mosko...@core-sound.com)
Core Sound LLC
www.core-sound.com<http://www.core-sound.com>
Home of TetraMic and OctoMic
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Re: [Sursound] Core Sound Announces OctoMic - First 2nd-order Ambisonics Microphone

[Len Moskowitz]

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

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Re: [Sursound] Core Sound Announces OctoMic - First 2nd-orderAmbisonics Microphone

[Len Moskowitz]

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 (mosko...@core-sound.com)
Core Sound LLC
www.core-sound.com
Home of TetraMic and OctoMic
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Re: [Sursound] (a little )help needed for ambisonics museum project

[Dave Malham]

As always, Fons has hit the nail on the head.

Dave

On 27 March 2018 at 19:40, Fons Adriaensen <f...@linuxaudio.org> wrote:

> On Tue, Mar 27, 2018 at 08:01:20AM +0100, Jack Reynolds wrote:
>
> > As far as I know, higher order ambisonics over loudspeakers has
> > a quite confined sweet spot. Higher order spherical harmonics
> > produce an in phase and out of phase signal in opposite speaker
> > pairs. So if you pan a signal towards a particular speaker, the
> > opposite speaker will produce a lower level antiphase signal,
> > which will work when you are positioned equidistant from both
> > speakers, causing a certain amount of nulling of the air pressure
> > at that spot, but positive particle velocity, like a figure 8 mic
> > pattern.
>
> It is unfortunate (and strange) that after all those years this sort
> of misinformation is still spread. I can only attribute it to what
> seem to be two properties of 'the web': anybody, no matter how misguided
> or malicious, can post whatever he/she wants, and the web never forgets.
>
> To put this straight: yes these antiphase signals in the opposite
> direction do exist. But first, their level goes down as order increases,
> and second, any decent AMB decoder will use this form of decoding only
> for low frequencies (where 'low' depends on the size of the rig).
> At mid and higher frequencies a 'max-rE' decode should be used, and
> at third order and above the produces very such low levels in the
> opposite direction that it doesn't matter anymore. Third and higher
> order will work very well for larger systems - IF DONE CORRECTLY.
>
> Ciao,
>
> --
> FA
>
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>



-- 

As of 1st October 2012, I have retired from the University.

These are my own views and may or may not be shared by the University

Dave Malham
Honorary Fellow, Department of Music
The University of York
York YO10 5DD
UK

'Ambisonics - Component Imaging for Audio'
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Re: [Sursound] (a little )help needed for ambisonics museum project

[Dave Malham]

re weird stuff than this :-)
> > >
> > > I hope I’ve made myself clear. If not: tell me.
> > >
> > > Med venlig hilsen/Best regards
> > >
> > > Søren Bendixen
> > > Composer/Sound Designer/Producer
> > >
> > > Winner of Monitor Industry Award 2016 for the exhibition “Gladiator”,
> At
> > Moesgaard Museum
> > >
> > > New album Music for exhibitions out 15 January 2017
> > >
> > >
> > >
> > >
> > >
> > > Company: Søren Bendixen & Anette Krag
> > > soerenbendi...@gmail.com
> > > +45 60624394
> > > www.soerenbendixen.com
> > > Facebook
> > > Soundcloud
> > >
> > >
> > >
> > >
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> >
>
>
>
> --
> Dr. Augustine Leudar
> Artistic Director Magik Door LTD
> Company Number : NI635217
> Registered 63 Ballycoan rd,
> Belfast BT88LL
> www.magikdoor.net
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-- 

As of 1st October 2012, I have retired from the University.

These are my own views and may or may not be shared by the University

Dave Malham
Honorary Fellow, Department of Music
The University of York
York YO10 5DD
UK

'Ambisonics - Component Imaging for Audio'
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Re: [Sursound] Core Sound Announces OctoMic - First 2nd-orderAmbisonics Microphone

[Stefan Schreiber]

Citando Len Moskowitz <lenmoskow...@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...      樂

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 (mosko...@core-sound.com)

 Core Sound LLC

 www.core-sound.com[1]

 Home of TetraMic and OctoMic



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Ligações:
-
[1] http://www.core-sound.com
[2]
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[Sursound] Busy, busy, busy..

[Dave Malham]

Good grief, what is everyone on this morning? My whole inbox was full of
Sursound mails. Haven't seen so many posts in donkey's years.
Wonderful,keep it up!

Dave

-- 

As of 1st October 2012, I have retired from the University.

These are my own views and may or may not be shared by the University

Dave Malham
Honorary Fellow, Department of Music
The University of York
York YO10 5DD
UK

'Ambisonics - Component Imaging for Audio'
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Re: [Sursound] Core Sound Announces OctoMic - First 2nd-order Ambisonics Microphone

[Jörn Nettingsmeier]

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
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Re: [Sursound] (a little )help needed for ambisonics museum project

[Augustine Leudar]

w archives and so on.
> >
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-- 
Dr. Augustine Leudar
Artistic Director Magik Door LTD
Company Number : NI635217
Registered 63 Ballycoan rd,
Belfast BT88LL
www.magikdoor.net
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Re: [Sursound] (a little )help needed for ambisonics museum project

[Pierre Alexandre Tremblay]

Getting carried away is the good stuff: it is music after all ;-)

Seriously with an irregular setup, one has to use imagination and invention. 
Very few tools deal with them ‘objectively’ (or I should say perceptually 
accurately)

p

> On 27 Mar 2018, at 23:33, Steven Boardman  wrote:
> 
> Or treat them all as one ring of 16.  Each inner and alternate outer
> separated by the same angle,  and compensated for distance.
> Then its all one circle,  and distance can be implied by filtering and
> source size, and/or by vbap.
> Maybe this has the added of advantage of one decode for all?
> It may also help smudge the sweet spot larger too, but I'm probably getting
> carried away. :)
> 
> S
> 
> 
> On Tue, 27 Mar 2018, 23:16 Dave McKevy,  wrote:
> 
>> Love the crossfade between spheres suggestion. I was thinking early in this
>> awesome thread: if arduino for motion detection to cue a crossfade between
>> spheres and binaural mix:)
>> 
>> On Tue, Mar 27, 2018, 6:00 PM Pierre Alexandre Tremblay <
>> tremb...@gmail.com>
>> wrote:
>> 
>>> This is a very interesting setup. Ambisonics expect your speakers to be
>> on
>>> an equidistant sphere (or circle). You have a few options with your
>> setup.
>>> Here are a few, in order of practicality for the composting process:
>>> 
>>> 1) use the free SpatGris plugin, in free mode, and position your
>>> loudspeakers on the grid where they will be, and pan along. Simple and
>>> efficient, amplitude based panning. You can choose the radius for each
>>> speaker.
>>> 
>>> 2) set 2 ambisonic arrays (one of each circles) and crossfade between
>> them
>>> 
>>> 3) set the full setup in a fake sphere, using the first 8 as you 0 deg
>>> elevation and the other at 45 deg: it won’t be perfect, but you could use
>>> elevation to crossfade between rings…
>>> 
>>> The trick is to try them: give each setup 2 h of play time, and see which
>>> one inspires you the most. They will all have quirks and you will compose
>>> around them. That is true for any setup, even stereo ;-)
>>> 
>>> p
>>> 
>>> 
>>> 
 On 27 Mar 2018, at 22:49, Søren Bendixen 
>>> wrote:
 
 allright
 my speaker setup (expected to be) 2 concentric circles with 8 speakers
>>> in both circles, so I will have to concentric circles of speakers.
 then also an inner circle more but all sound in this in headphones.
 
> Den 27. mar. 2018 kl. 23.43 skrev Pierre Alexandre Tremblay <
>>> tremb...@gmail.com>:
> 
>> If done correctly, there is no sweep spot issue.
> 
> Sorry, to be accurate: there is no more sweet spot issue than vbap. It
>>> is not better, nor worse. Both have a sound, strengths and weaknesses.
> 
> If you use asymmetrical speaker layout, far from a regular setup, all
>>> will fail. You just have to choose your colour of problems.
> 
> p
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 Med venlig hilsen/Best regards
 
 Søren Bendixen
 Composer/Sound Designer/Producer
 
 Winner of Monitor Industry Award 2016 for the exhibition “Gladiator”,
>> At
>>> Moesgaard Museum
 
 New album Music for exhibitions out 15 January 2017
 
 
 
 
 
 Company: Søren Bendixen & Anette Krag
 soerenbendi...@gmail.com
 +45 60624394
 www.soerenbendixen.com
 Facebook
 Soundcloud
 
 
 
 
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