Discussion:
Rode Soundfield NT-SF1
(too old to reply)
Courville, Daniel
2018-04-11 10:26:00 UTC
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This should be interesting...

http://www.rode.com/nt-sf1

https://vimeo.com/264158943
Dave Hunt
2018-04-11 17:30:35 UTC
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Hi,

Also this, a sound field microphone to mount on top of a camera:

http://www.rode.com/blog/all/videomic-soundfield-abdi

Seems like a short while ago that it was on their website looking more like a forthcoming product.

https://www.gear4music.com/PA-DJ-and-Lighting/Rode-VideoMic-SoundField/1U73

Described as "Coming Soon". I did see a video, but it seems to have disappeared.

It looks like they may have dropped this concept for the time being. Presumably they had problems with the housing being near the capsules and quite large. As shown, it would have the body of the mic in the down position, so perhaps not too much of a problem.


It looked like an extension of

http://www.rode.com/microphones/stereovideomicx

with similar mounting, controls, and windshields, and (as I remember) sensible headphone monitoring.

I have one of these, and have been impressed.

An unusual looking microphone, but quality and very practical.

Then, there's this

http://www.rode.com/news/new-rode-i16-offers-360-surround-recording-for-ios-devices

Ciao,

Dave Hunt


On 11 Apr 2018, at 17:00, sursound-***@music.vt.edu wrote:

> From: "Courville, Daniel" <***@uqam.ca>
> Subject: [Sursound] Rode Soundfield NT-SF1
> Date: 11 April 2018 11:26:00 BST
> To: Sursound <***@music.vt.edu>
>
>
> This should be interesting...
>
> http://www.rode.com/nt-sf1
>
> https://vimeo.com/264158943
>
>
Paul Hodges
2018-04-11 17:40:30 UTC
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--On 11 April 2018 10:26 +0000 "Courville, Daniel"
<***@uqam.ca> wrote:

> http://www.rode.com/nt-sf1

Given the amount of space they've left behind the capsules, it seems a
shame they didn't take the opportunity to mount them closer. Perhaps
the space is crucial to the performance of the capsules.

I wonder how the capsules will compare with those on the SPS-200, given
that the projected cost is a mere fraction of that (if the price quoted
in the video is in Australian dollars, then it's only a quarter of the
price of the SPS-200!).

Paul

--
Paul Hodges
Jack Reynolds
2018-04-12 08:36:44 UTC
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There is an optimum radius of about 15mm, below which the bottom end begins to suffer I’m told.
Paul Hodges
2018-04-12 09:12:48 UTC
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--On 12 April 2018 09:36 +0100 Jack Reynolds
<***@gmail.com> wrote:

> There is an optimum radius of about 15mm, below which the bottom end
> begins to suffer I'm told.

I would guess this is practical rather than theoretical; determined by
a combination of noise (because of the gain required in the
differences) and the difficulty of precise calibration at low
frequencies.

Paul

--
Paul Hodges
Fons Adriaensen
2018-04-12 19:43:42 UTC
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On Thu, Apr 12, 2018 at 10:12:48AM +0100, Paul Hodges wrote:
> --On 12 April 2018 09:36 +0100 Jack Reynolds
> <***@gmail.com> wrote:
>
> > There is an optimum radius of about 15mm, below which the bottom end
> > begins to suffer I'm told.
>
> I would guess this is practical rather than theoretical; determined by
> a combination of noise (because of the gain required in the
> differences) and the difficulty of precise calibration at low
> frequencies.

The radius would matter if omni capsules are used. In that case
the practical lower limit if you want the 1st order response to
go down to the 20-50 Hz range is around the size of the Eigenmic,
somwat more than 15 mm radius. And even then that requires very
careful calibration and stability.

Tetrahedral mics use near cardioid capsules, and extracting the
first order AMB components doesn't require a minimum distance
between them.

Ciao,

--
FA
Jack Reynolds
2018-04-12 22:33:04 UTC
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So is a larger radius A-Format mic not a problem then? I always thought the radius dictated the upper frequency limit for spatial aliasing.
Fernando Lopez-Lezcano
2018-04-13 17:14:57 UTC
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On 04/12/2018 03:33 PM, Jack Reynolds wrote:
> So is a larger radius A-Format mic not a problem then? I always thought the radius dictated the upper frequency limit for spatial aliasing.

The radius defines the frequency at which the array stops behaving like
a coincident array. Above that frequency filters are normally used to
try to compensate for that, but they cannot equalize the array equally
well in all directions. A smaller array will be better in the sense that
those problems will happen at higher frequencies.

-- Fernando
Jack Reynolds
2018-04-13 17:23:20 UTC
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That’s what I thought.
I have also heard that a radius smaller than 15mm or so has detrimental effects on the low end
Fernando Lopez-Lezcano
2018-04-13 17:58:57 UTC
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On 04/13/2018 10:23 AM, Jack Reynolds wrote:
> That’s what I thought.
> I have also heard that a radius smaller than 15mm or so has detrimental effects on the low end

The is probably related to the size of the capsules. As you bring the
radius down you have to use smaller capsules and the low frequency
response will suffer (for example, I can see a big difference in low end
response between microphones I have built using 10mm capsules - array
radius of 9.2mm - vs. 14mm capsules - array radius 11mm, but that is
because of the capsules themselves).

-- Fernando
David Pickett
2018-04-14 08:17:04 UTC
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In
https://www.waves.com/ambisonics-explained-guide-for-sound-engineers it says:

"...there are two conventions within the Ambisonics B-format
standard: AmbiX and FuMa. They are quite similar, but not
interchangeable: they differ by the sequence in which the four
channels are arranged..."

Could someone be so kind as to tell me what the exact sequence and
level differences are, so that I can convert first and second order
B-format files between the two standards? (I am working with separate
B-format wavfiles -- not multichannel wavfiles -- and as far as I can
find there are no plugins for this situation.)

Many thanks in advance!

David
Jack Reynolds
2018-04-14 08:55:25 UTC
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FuMa is WXYZ and ambiX is WYZX with SN3D normalisation.
I forget the gains off the top of my head, but will have a look and get back if no one else has chipped in.
J
Fons Adriaensen
2018-04-14 10:55:48 UTC
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On Sat, Apr 14, 2018 at 09:55:25AM +0100, Jack Reynolds wrote:

> FuMa is WXYZ and ambiX is WYZX with SN3D normalisation.
> I forget the gains off the top of my head, but will have
> a look and get back if no one else has chipped in.


Convert FuMa to Ambix
---------------------

ACN-0 = 1.4142 * W (+3.01 dB)
ACN-1 = Y
ACN-2 = Z
ACN-3 = X
------
ACN-4 = 0.8660 * V (-1.25 dB)
ACN-5 = 0.8660 * T
ACN-6 = R
ACN-7 = 0.8660 * S
ACN-8 = 0.8660 * U
------
ACN-9 = 0.7906 * Q (-2.04 dB)
ACN-10 = 0.7454 * O (-2.55 dB)
ACN-11 = 0.8433 * M (-1.48 dB)
ACN-12 = K
ACN-13 = 0.8433 * L
ACN-14 = 0.7454 * N
ACN-15 = 0.7906 * P

Ambix files should use CAF (Apple's Core Audio Format),
but in practice WAVEX is used as well.


Convert Ambix to Fuma
---------------------

W = 0.7071 * ACN-0 (-3.01 dB)
X = ACN-3
Y = ACN-1
Z = ACN-2
-----
R = ACN-6
S = 1.1547 * ACN-7 (+1.25 dB)
T = 1.1547 * ACN-5
U = 1.1547 * ACN-8
V = 1.1547 * ACN-4
-----
K = ACN-12
L = 1.1859 * ACN-13 (+1.48 dB)
M = 1.1859 * ACN-11
N = 1.3416 * ACN-14 (+2.55 dB)
O = 1.3416 * ACN-10
P = 1.2649 * ACN-15 (+2.04 dB)
Q = 1.2649 * ACN-9


Ciao,

--
FA
David Pickett
2018-04-14 15:28:57 UTC
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Thanks, Fons. I was hoping it was something as simple as this. I
failed to find anything on the internet that expresses the
relationships so simply. Did I actually miss a page?

David

At 12:55 14-04-18, Fons Adriaensen wrote:
>On Sat, Apr 14, 2018 at 09:55:25AM +0100, Jack Reynolds wrote:
>
>> FuMa is WXYZ and ambiX is WYZX with SN3D normalisation.
>> I forget the gains off the top of my head, but will have
>> a look and get back if no one else has chipped in.
>
>
>Convert FuMa to Ambix
>---------------------
>
>ACN-0 = 1.4142 * W (+3.01 dB)
>ACN-1 = Y
>ACN-2 = Z
>ACN-3 = X
>------
>ACN-4 = 0.8660 * V (-1.25 dB)
>ACN-5 = 0.8660 * T
>ACN-6 = R
>ACN-7 = 0.8660 * S
>ACN-8 = 0.8660 * U
>------
>ACN-9 = 0.7906 * Q (-2.04 dB)
>ACN-10 = 0.7454 * O (-2.55 dB)
>ACN-11 = 0.8433 * M (-1.48 dB)
>ACN-12 = K
>ACN-13 = 0.8433 * L
>ACN-14 = 0.7454 * N
>ACN-15 = 0.7906 * P
>
>Ambix files should use CAF (Apple's Core Audio Format),
>but in practice WAVEX is used as well.
>
>
>Convert Ambix to Fuma
>---------------------
>
>W = 0.7071 * ACN-0 (-3.01 dB)
>X = ACN-3
>Y = ACN-1
>Z = ACN-2
>-----
>R = ACN-6
>S = 1.1547 * ACN-7 (+1.25 dB)
>T = 1.1547 * ACN-5
>U = 1.1547 * ACN-8
>V = 1.1547 * ACN-4
>-----
>K = ACN-12
>L = 1.1859 * ACN-13 (+1.48 dB)
>M = 1.1859 * ACN-11
>N = 1.3416 * ACN-14 (+2.55 dB)
>O = 1.3416 * ACN-10
>P = 1.2649 * ACN-15 (+2.04 dB)
>Q = 1.2649 * ACN-9
>
>
>Ciao,
>
>--
>FA
>_______________________________________________
>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.
Fons Adriaensen
2018-04-14 15:53:40 UTC
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On Sat, Apr 14, 2018 at 05:28:57PM +0200, David Pickett wrote:

> Thanks, Fons. I was hoping it was something as simple as this. I failed to
> find anything on the internet that expresses the relationships so simply.
> Did I actually miss a page?

Not one I know of. Some of my programs (e.g. Ambdec) do the conversion
when required, so I just took these gain figures from my source code.

Ciao,

--
FA
Jörn Nettingsmeier
2018-04-17 20:46:54 UTC
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On 04/14/2018 05:53 PM, Fons Adriaensen wrote:
> On Sat, Apr 14, 2018 at 05:28:57PM +0200, David Pickett wrote:
>
>> Thanks, Fons. I was hoping it was something as simple as this. I failed to
>> find anything on the internet that expresses the relationships so simply.
>> Did I actually miss a page?
>
> Not one I know of. Some of my programs (e.g. Ambdec) do the conversion
> when required, so I just took these gain figures from my source code.

There is
https://en.wikipedia.org/wiki/Ambisonic_data_exchange_formats#Reference_table_of_layouts_and_normalisations
, which could use a few eyeballs and probably be made a little friendlier.



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

Meister für Veranstaltungstechnik (Bühne/Studio), Tonmeister VDT
http://stackingdwarves.net
Jon Honeyball
2018-04-16 08:15:51 UTC
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The wonderful thing about standards is the opportunity to have lots of them

jon

> On 14 Apr 2018, at 09:55, Jack Reynolds <***@gmail.com> wrote:
>
> FuMa is WXYZ and ambiX is WYZX with SN3D normalisation.
> I forget the gains off the top of my head, but will have a look and get back if no one else has chipped in.
> J
> _______________________________________________
> 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.
Bearcat M. Şándor
2018-04-17 17:54:17 UTC
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Is one standard considered better (or more common) than the other?

On Mon, Apr 16, 2018 at 2:15 AM, Jon Honeyball <***@jonhoneyball.com> wrote:

> The wonderful thing about standards is the opportunity to have lots of them
>
> jon
>
> > On 14 Apr 2018, at 09:55, Jack Reynolds <***@gmail.com>
> wrote:
> >
> > FuMa is WXYZ and ambiX is WYZX with SN3D normalisation.
> > I forget the gains off the top of my head, but will have a look and get
> back if no one else has chipped in.
> > J
> > _______________________________________________
> > 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.
>
> _______________________________________________
> 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.
>



--
Bearcat M. Şándor
Feline Soul Systems LLC
Voice: 872.CAT.SOUL (872.228.7685)
Fax: 406.235.7070
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Jack Reynolds
2018-04-17 19:03:59 UTC
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AmbiX is more common these days
Paul Hodges
2018-04-14 10:42:20 UTC
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--On 14 April 2018 10:17 +0200 David Pickett <***@fugato.com> wrote:

> (I am working with separate B-format wavfiles -- not multichannel
> wavfiles -- and as far as I can find there are no plugins for this
> situation.)

There are many reasons not to use Steinberg's WaveLab for ambisonics
(though it works fine for me, doing just 1st order), but it is standard
practice in WaveLab to have a montage with a file per channel, writing
four separate files for output, but having a four-channel plugin in the
master section. It's how I do /all/ my ambisonic work at present! (it
can also write 4-channel files for distribution).

Paul

--
Paul Hodges
David Pickett
2018-04-14 15:42:11 UTC
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I have never used Steinberg's Wavelab for anything. :) But it sounds
like it has similar drawbacks to the otherwise excellent Samplitude,
which I DO use.

Incidentally, one of the drawbacks of multichannel wavfiles for HOA
is their large size for any reasonable length of musical composition.
At 48kHz, a 9-channel 2nd order file takes c. 74MB for 1 minute of
music. Alternatively, 1GB lasts about 13.5 minutes in 2nd order or
about 30.4 mins in 1st order.

David

At 12:42 14-04-18, Paul Hodges wrote:
>--On 14 April 2018 10:17 +0200 David Pickett <***@fugato.com> wrote:
>
>> (I am working with separate B-format wavfiles -- not multichannel
>> wavfiles -- and as far as I can find there are no plugins for this
>> situation.)
>
>There are many reasons not to use Steinberg's WaveLab for ambisonics
>(though it works fine for me, doing just 1st order), but it is standard
>practice in WaveLab to have a montage with a file per channel, writing
>four separate files for output, but having a four-channel plugin in the
>master section. It's how I do /all/ my ambisonic work at present! (it
>can also write 4-channel files for distribution).
>
>Paul
>
>--
>Paul Hodges
>
>_______________________________________________
>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.
Fons Adriaensen
2018-04-14 15:51:21 UTC
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On Sat, Apr 14, 2018 at 05:42:11PM +0200, David Pickett wrote:

> Incidentally, one of the drawbacks of multichannel wavfiles for HOA is their
> large size for any reasonable length of musical composition. At 48kHz, a
> 9-channel 2nd order file takes c. 74MB for 1 minute of music. Alternatively,
> 1GB lasts about 13.5 minutes in 2nd order or about 30.4 mins in 1st order.

This is one of the reasons why the CAF file format was chosen for Ambix.
It doesn't have the 32-bit file size limit of most other formats (all
size fields are 64-bit).

Ciao,

--
FA
David Pickett
2018-04-14 17:22:31 UTC
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At 17:51 14-04-18, Fons Adriaensen wrote:
>On Sat, Apr 14, 2018 at 05:42:11PM +0200, David Pickett wrote:
>
>> Incidentally, one of the drawbacks of multichannel wavfiles for
HOA is their
>> large size for any reasonable length of musical composition. At 48kHz, a
>> 9-channel 2nd order file takes c. 74MB for 1 minute of music.
Alternatively,
>> 1GB lasts about 13.5 minutes in 2nd order or about 30.4 mins in 1st order.
>
>This is one of the reasons why the CAF file format was chosen for Ambix.
>It doesn't have the 32-bit file size limit of most other formats (all
>size fields are 64-bit).

Doesnt this limit one to the Apple environment?

David
Marc Lavallée
2018-04-14 17:38:10 UTC
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Le 2018-04-14 à 01:22 PM, David Pickett a écrit :

>
> At 17:51 14-04-18, Fons Adriaensen wrote:
> >On Sat, Apr 14, 2018 at 05:42:11PM +0200, David Pickett wrote:
> >
> >> Incidentally, one of the drawbacks of multichannel wavfiles for HOA
> is their
> >> large size for any reasonable length of musical composition. At
> 48kHz, a
> >> 9-channel 2nd order file takes c. 74MB for 1 minute of music.
> Alternatively,
> >> 1GB lasts about 13.5 minutes in 2nd order or about 30.4 mins in 1st
> order.
> >
> >This is one of the reasons why the CAF file format was chosen for Ambix.
> >It doesn't have the 32-bit file size limit of most other formats (all
> >size fields are 64-bit).
>
> Doesnt this limit one to the Apple environment?
>
> David

Hi David.

Short answer: no.

More info (and a sample file) here:
http://samplephotovideo.com/2015/12/download-caf-apple-core-audio-format-caf/

Any software using libsndfile (ex: sox, ffmpeg) can read (and possibly
write) CAF files:
http://www.mega-nerd.com/libsndfile/

--
Marc
Jack Reynolds
2018-04-14 18:08:54 UTC
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RF64 is also an option for 64bit WAV files via libsndfile.
I am attempting to add BW64 to the library for ADM purposes, but it’s taking a while.
J
David Pickett
2018-04-14 18:28:09 UTC
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I can handle those. :)

At 20:08 14-04-18, Jack Reynolds wrote:
>
>RF64 is also an option for 64bit WAV files via libsndfile.
>I am attempting to add BW64 to the library for ADM purposes, but
>it’s taking a while.
>
>_______________________________________________
>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.
Jon Honeyball
2018-04-16 08:18:40 UTC
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On 14 Apr 2018, at 16:42, David Pickett <***@fugato.com<mailto:***@fugato.com>> wrote:

Incidentally, one of the drawbacks of multichannel wavfiles for HOA is their large size for any reasonable length of musical composition. At 48kHz, a 9-channel 2nd order file takes c. 74MB for 1 minute of music. Alternatively, 1GB lasts about 13.5 minutes in 2nd order or about 30.4 mins in 1st order

It doesn’t help when some equipment fails to play back more than one file in sequence. The latest deeply cute Sound Devices will only play one file, and not continue on to the next one. So your playback time is limited to some 15 minutes (at best resolution) and it only records polywav.

Talk about gun/foot/shoot…

(confirmed with SD tech support staff at NAB last week in vegas)

Jon
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David Pickett
2018-04-16 08:45:59 UTC
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At 10:18 16-04-18, Jon Honeyball wrote:
>
>On 14 Apr 2018, at 16:42, David Pickett
><***@fugato.com<mailto:***@fugato.com>> wrote:
>
>Incidentally, one of the drawbacks of multichannel wavfiles for HOA is
>their large size for any reasonable length of musical composition. At
>48kHz, a 9-channel 2nd order file takes c. 74MB for 1 minute of music.
>Alternatively, 1GB lasts about 13.5 minutes in 2nd order or about 30.4
>mins in 1st order
>
>It doesn’t help when some equipment fails to play back more than one
>file in sequence. The latest deeply cute Sound Devices will only play
>one file, and not continue on to the next one. So your playback time
>is limited to some 15 minutes (at best
resolution) and it only records polywav.
>
>Talk about gun/foot/shoot…
>
>(confirmed with SSD tech support staff at NAB last week in vegas)
>

Indeed. The latest Oppo box has the same problem.
But perhaps people only listen to 4 minute singles these days.

I quite understand that the demands made by one
file per track recordings on writing to storage
in real time are currently too great to handle,
whereas boxes like the Alesis HD24 and RME UFX
will store between 24 and 60 hi res tracks using
multitrack files and proprietary storage formats;
but on the other hand, why not either write
soft/firm-ware that will link these together, or
separate them into single files, for playback?

David
Yvan Grabit
2018-04-26 17:31:43 UTC
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Hi

sorry for the late answer,
Wavelab, Cubase, Nuendo supports RF64 format (Broadcast Wave) allowing to handle big file (more than 2Gb).
It is done automatically when you record in Wave format, as soon as the size of the file is bigger than 2Gb it will change to a RF64 file.


Cheers

Yvan
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Yvan Grabit mailto:***@steinberg.de
Technical Manager - Technology Group Phone: +49-40-21035125
Steinberg Media Technologies GmbH Fax : +49-40-21035300
Beim Strohhause 31 D-20097 Hamburg/Germany
http://www.steinberg.net
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

-----"Sursound" <sursound-***@music.vt.edu> wrote: -----To: Surround Sound discussion group <***@music.vt.edu>
From: Jon Honeyball
Sent by: "Sursound"
Date: 04/16/2018 10:19AM
Subject: Re: [Sursound] Steinberg and Multichannel files


On 14 Apr 2018, at 16:42, David Pickett <***@fugato.com<mailto:***@fugato.com>> wrote:

Incidentally, one of the drawbacks of multichannel wavfiles for HOA is their large size for any reasonable length of musical composition. At 48kHz, a 9-channel 2nd order file takes c. 74MB for 1 minute of music. Alternatively, 1GB lasts about 13.5 minutes in 2nd order or about 30.4 mins in 1st order

It doesn’t help when some equipment fails to play back more than one file in sequence. The latest deeply cute Sound Devices will only play one file, and not continue on to the next one. So your playback time is limited to some 15 minutes (at best resolution) and it only records polywav.

Talk about gun/foot/shoot…

(confirmed with SD tech support staff at NAB last week in vegas)

Jon
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Jon Honeyball
2018-05-10 15:55:58 UTC
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Bought the Sennheiser Ambeo binaural recording headphones. I wanted some on-ear mics, and this seemed a relatively cheap and easy way to solve the problem.

(Background requirement — wanting to measure the spectral shape of noise in a motorbike helmet, so when i am doing noise testing using my GRAS artificial ear and cheek, I am at least driving it with the sort of spectral noise that you actually get in a helmet. Yes, its not precise, but it was an interesting bit of “I wonder…” fun R&D)

The Ambeo headphones plug into an iPhone using a lightening port. This powers the headphones, acts as the IO for the mics and headphones etc.

Sennheiser recommends an app from Apogee called MetaRecorder. I downloaded it. It only records for 60 seconds in the free version. Yes, 60 seconds. To get proper length recording you have to cough up £4.99 for a single device full version

So I paid

I did some recordings, and decided to use its “Send to Dropbox” feature to copy my recordings out. Dropbox throws a warning that Apogee is using an old API that will stop working in a few months. Tried it anyway. That doesn’t work, output to Dropbox keels over. Contacted Apogee support. They admit it doesn’t work. It might get fixed. But they have no timescale.

Now I quite like the Ambeo headphone/binaural mic thing. Its interesting, its small, its cute, and the recordings are adequate (even though you only get a choice of two fixed record levels — errr, why???)

The Apogee software is incomplete, buggy and doesn’t do what it claims. Yes, I expected rather better from Apogee and Sennheiser.

Jon
Andres Pérez López
2018-04-14 16:04:36 UTC
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Dear David,

regarding Ambisonics normalization ("level differences"), you might find
interesting the following article by T. Carpentier: "Normalization
Schemes in Ambisonic: Does it Matter?
<http://www.aes.org/e-lib/browse.cfm?elib=18645>".

Best,

Andrés



El 14/04/18 a las 10:17, David Pickett escribió:
> In
> https://www.waves.com/ambisonics-explained-guide-for-sound-engineers
> it says:
>
> "...there are two conventions within the Ambisonics B-format standard:
> AmbiX and FuMa. They are quite similar, but not interchangeable: they
> differ by the sequence in which the four channels are arranged..."
>
> Could someone be so kind as to tell me what the exact sequence and
> level differences are, so that I can convert first and second order
> B-format files between the two standards? (I am working with separate
> B-format wavfiles -- not multichannel wavfiles -- and as far as I can
> find there are no plugins for this situation.)
>
> Many thanks in advance!
>
> David
>
>
> _______________________________________________
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> https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe
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Chris Woolf
2018-04-14 10:49:07 UTC
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I'd be very interested to know the argument behind that.

Although bass response is affected by size in speakers I don't know of
any reason for that in microphones.

Chris Woolf


On 13/04/2018 18:58, Fernando Lopez-Lezcano wrote:
> On 04/13/2018 10:23 AM, Jack Reynolds wrote:
>> That’s what I thought.
>> I have also heard that a radius smaller than 15mm or so has
>> detrimental effects on the low end
>
> The is probably related to the size of the capsules. As you bring the
> radius down you have to use smaller capsules and the low frequency
> response will suffer (for example, I can see a big difference in low
> end response between microphones I have built using 10mm capsules -
> array radius of 9.2mm - vs. 14mm capsules - array radius 11mm, but
> that is because of the capsules themselves).
>
> -- Fernando
>
> _______________________________________________
> Sursound mailing list
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> https://mail.music.vt.edu/mailman/listinfo/sursound - unsubscribe
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Fons Adriaensen
2018-04-14 11:27:44 UTC
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On Sat, Apr 14, 2018 at 11:49:07AM +0100, Chris Woolf wrote:

> I'd be very interested to know the argument behind that.
>
> Although bass response is affected by size in speakers I don't know of any
> reason for that in microphones.

This has little to do with response, and all with directivity.

It's perfectly possible to have a tiny mic with excellent bass
response. But it's quite difficult to maintain directivity
as size goes down. Also self-noise will be worse for small
capsules - they just get less acoustic energy.

If the capsules don't provide directivity, then it has to
be obtained by amplifying the differences between capsule
outputs. The required gain (for first order) is proportional
to the ratio wavelenght / capsule distance, so it will be
higher as frequency and/or mic size go down.
There are practical limits to what can be done this way,
and that more or less imposes a minimum practical size.

Ciao,

--
FA
Chris Woolf
2018-04-12 09:20:20 UTC
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On 11/04/2018 18:40, Paul Hodges wrote:
> ...
> I wonder how the capsules will compare with those on the SPS-200, given
> that the projected cost is a mere fraction of that (if the price quoted
> in the video is in Australian dollars, then it's only a quarter of the
> price of the SPS-200!).
>
>
While I have been sceptical in the past about Rode products I have to
admit that many of their more recent ones have been remarkably good for
the price. The company's willingness to commit to a lot of capital
expenditure in automating manufacture, on the presumption of being able
to sell high volumes, has made low cost manufacture possible. They seem
able to compete with Far East pricing, yet maintain Western engineering
values - a scary feat.

They've also bought Peter Schillebeeckx with the Soundfield remnants, so
they do have some proper expertise too.

Only time will tell if the product really works, but it can't be
dismissed out of hand now.

Chris Woolf


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Rudy Chalupa
2018-04-16 13:07:46 UTC
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https://xkcd.com/927/



-----Original Message-----
From: Jon Honeyball <***@jonhoneyball.com>
To: Surround Sound discussion group <***@music.vt.edu>
Sent: Mon, Apr 16, 2018 4:19 am
Subject: Re: [Sursound] Ambix to FuMa conversion

The wonderful thing about standards is the opportunity to have lots of them

jon

> On 14 Apr 2018, at 09:55, Jack Reynolds <***@gmail.com> wrote:
>
> FuMa is WXYZ and ambiX is WYZX with SN3D normalisation.
> I forget the gains off the top of my head, but will have a look and get back if no one else has chipped in.
> J
> _______________________________________________
> 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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Dave Hunt
2018-04-18 17:30:42 UTC
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Hi,

I suppose that the effective answer is that "the most common standard is the standard".

Rather worrying considering the effects this can have on social media.

The two standards we are talking of are both well defined and agreed on, and reasonably equivalent, and conversion between them on a computer, or DSP box is fairly trivial. It could even be done in analogue hardware, though I don't foresee that demand for it would make it commercially viable.

Ambix format is a shift from history, and seems to make most sense mathematically. A bit strange to those of us brought up on FuMa, especially with X delegated to the fourth channel, and "less important" than Z. .

Ciao,

Dave Hunt


On 18 Apr 2018, at 17:00, sursound-***@music.vt.edu wrote:

> From: Bearcat M. Şándor <***@gmail.com>
> Subject: Re: [Sursound] Ambix to FuMa conversion
> Date: 17 April 2018 18:54:17 BST
> To: Surround Sound discussion group <***@music.vt.edu>
>
>
> Is one standard considered better (or more common) than the other?
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