Re: [Sursound] 3 point XY - Anyone ever heard about this?

[Michael Williams]

Hi Chris
On the advice from David Josephson I have just joined.
Thanks for the plug.
You will soon receiving a copy of my latest version of 
Stereo/Surround/3D Audio book.

Iam looking for every way that I can use to publisize the book.
Amities Mike
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Re: [Sursound] 3 point XY - Anyone ever heard about this?

[Sampo Syreeni]

On 2022-12-05, Fons Adriaensen wrote:


Does anyone ever heard of a system described as "3 point XY"?


Sounds like hogwash and snakeoil.


It certainly is not.

If the three mics are coincident (in the horizontal plane),
you can combine their signals to obtain

- An omni response
- A front/back fig-8
- A left/right fig-8


Okay, crap. XY stereo apparently is not well-defined. Your version is 
about XY as frontally oriented cardioid responses. There you can indeed 
recover full pantophony from any three such mics, which are linearly 
independent. And in fact I've already gone with this definition when I 
wrote up the OggPCM channel map definition. I even defined XY like you 
do, there.


However, the basic version of XY I was originally taught utilizes two 
pure velocity mics in quadrature. I believe that comes from Blumlein's 
early work. If you go by that definition, no combination of such 
coincident "XY"'s can ever recover W.


Whereupon my outburst. Might we agree to call it a glitch in 
nomenclature? Shoulda known better, but reverted to an earlier time?

--
Sampo Syreeni, aka decoy - de...@iki.fi, http://decoy.iki.fi/front
+358-40-3751464, 025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2
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Re: [Sursound] 3 point XY - Anyone ever heard about this?

[Sampo Syreeni]

On 2022-12-05, Fons Adriaensen wrote:


On Mon, Dec 05, 2022 at 07:07:08AM +0200, Sampo Syreeni wrote:


On 2022-12-04, Thorsten Michels wrote:


Does anyone ever heard of a system described as "3 point XY"?


Sounds like hogwash and snakeoil.


It certainly is not.

If the three mics are coincident (in the horizontal plane),
you can combine their signals to obtain

- An omni response
- A front/back fig-8
- A left/right fig-8


Fuck me. XY isn't well defined. Even I believed, when writing up the 
OggPCM specification (drart still) that it's all cardioids 45 degrees 
apart from center front.


Reducing that to the ambisonic framework, well, obviously you can *then* 
recover WXY as soon as you have a linearly independent combination of 
any two such pairs, or any three cardioids (which should not be called 
XY then, because they are not paired).


What I was refererring to above was the older crossed pair. Perchance 
from the Blumlein era. "Crossed eights". So, two dipoles, not cardioids. 
Per standard theory, no amount of those in an coincident mic can ever 
recover W, or anything above first order.


Maybe the XY terminology led me astray? Because whether you take it in 
its established sense of, yes, cardioids, or the older one of crossed 
dipoles, even three such linearly independent pairs (6 channels) leads 
to an overcomplete problem wrt POA, and no real help towards HOA.

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Sampo Syreeni, aka decoy - de...@iki.fi, http://decoy.iki.fi/front
+358-40-3751464, 025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2
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Re: [Sursound] 3 point XY - Anyone ever heard about this?

[Paul Hodges]

From:   Sampo Syreeni  


Sounds like hogwash and snakeoil. 

A reminder:
https://www.michaelgerzonphotos.org.uk/microphones-calrecs.html


Paul
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Re: [Sursound] 3 point XY - Anyone ever heard about this?

[Chris Woolf]

Michael Williams is undoubtedly an oddity in our audio world, but he is 
a great experimenter and his ideas are all grounded in solid science. 
I've known him for a great many years and he's never come up with 
hogwash or snake-oil in all that time.


Chris Woolf


On 05/12/2022 13:50, Fons Adriaensen wrote:

On Mon, Dec 05, 2022 at 07:07:08AM +0200, Sampo Syreeni wrote:


On 2022-12-04, Thorsten Michels wrote:


Does anyone ever heard of a system described as "3 point XY"?

Sounds like hogwash and snakeoil.

It certainly is not.

If the three mics are coincident (in the horizontal plane),
you can combine their signals to obtain

- An omni response
- A front/back fig-8
- A left/right fig-8

and these three in turn can be mixed to obtain any first
order mic with an horizontal axis.


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Re: [Sursound] 3 point XY - Anyone ever heard about this?

[Fons Adriaensen]

On Mon, Dec 05, 2022 at 07:07:08AM +0200, Sampo Syreeni wrote:

> On 2022-12-04, Thorsten Michels wrote:
> 
> > Does anyone ever heard of a system described as "3 point XY"?
> 
> Sounds like hogwash and snakeoil.

It certainly is not.

If the three mics are coincident (in the horizontal plane),
you can combine their signals to obtain

- An omni response
- A front/back fig-8
- A left/right fig-8

and these three in turn can be mixed to obtain any first
order mic with an horizontal axis.

-- 
FA


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Re: [Sursound] 3 point XY - Anyone ever heard about this?

[Sampo Syreeni]

On 2022-12-04, Fons Adriaensen wrote:

All such schemes with three coincident mics (e.g. three cardiods, an 
omni and two fig-8, etc.) are equivalent in the sense that there is a 
simple linear transform from each of them one any other.


Though since two already suffice, the linear transform back to the 
instantaneous soundfield is overcomplete. As such you can perchance use 
three microphones to cut back on directional errors, or maybe average 
out some noise. Presuming your hypercardioid has some higher order 
directional components instead of just being of just first order, maybe 
you can utilize the now-trifold symmetry to bring some extra 
directionality into play. (Cut into TriField, frontally.)


But most likely not. Most likely you'll end up with a compact mic array, 
with little or any capability above the classical SoundField.


So unless you exclude such trivial processing, and insist on a system 
with a one-to-one correspondence of mics and speakers, it really 
doesn't matter which one you use.


Even that one-to-one correspodence wouldn't help, if the microphones are 
cardioids, hypercardioids, any which way. Because if their directional 
patterns do not possess characteristics above first orrder, they can be 
returned back to a first order mic by some linear transformation. They 
are all equivalent to each other — and where they are not, at first 
order, they fail the isotropicity POA Ambisonic tries to achieve.

--
Sampo Syreeni, aka decoy - de...@iki.fi, http://decoy.iki.fi/front
+358-40-3751464, 025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2
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Re: [Sursound] 3 point XY - Anyone ever heard about this?

[Sampo Syreeni]

On 2022-12-04, Thorsten Michels wrote:


Does anyone ever heard of a system described as "3 point XY"?


Sounds like hogwash and snakeoil.

If you do XY, you only need two orthogonal mics. It's *possible* that 
you could utilize extra mics in order to do directional, amplitude and 
spectral stabilisation. But it's unlikely to be useful, because the 
physical quadrature in increasing numbers of directional microphones in 
the horizontal plane is apt to become more unstable at the margin 
(leading to more noise), and it's very difficult cancel XY-style 
pantophonic components unless you truly to go a periphonic and as such a 
much higher order mic.

--
Sampo Syreeni, aka decoy - de...@iki.fi, http://decoy.iki.fi/front
+358-40-3751464, 025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2
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Re: [Sursound] 3 point XY - Anyone ever heard about this?

[Fons Adriaensen]

On Sun, Dec 04, 2022 at 07:08:12PM +, Thorsten Michels wrote:
 
> It seems to be a very special (aka very unknown) setup with three
> supercardioids.
> In the YT-Video https://www.youtube.com/watch?v=cA6MZPNVyZU, (only available
> in German) the author claims, that this setup is based on something Mr.
> Michael Williams has published.

>From the video it seems this is a coincident setup.

All such schemes with three coincident mics (e.g. three
cardiods, an omni and two fig-8, etc.) are equivalent in
the sense that there is a simple linear transform from
each of them one any other.

So unless you exclude such trivial processing, and insist
on a system with a one-to-one correspondence of mics and
speakers, it really doesn't matter which one you use.

-- 
FA


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Re: [Sursound] 3 point XY - Anyone ever heard about this?

[Marc Lavallée]

Le 2022-12-04 à 14 h 30, David Stalling a écrit :

PS I don't think the 3 point XY technique is mentioned in the article but
just to give you a starting point for digging further.


Official web site of Michael Williams: https://www.mmad.info/

(Content of the "soundsscot.com" web site was migrated to "mmad.info" in 
2009)


There's articles, tons of microphone setups... And a mention of Triphony 
(3 point XY?), without much details:


https://www.mmad.info/MAD/Ch_n_cov.htm , 
https://www.mmad.info/MAD/3Ch/3ch.htm


Cool pictures of his "Crocodile" optical tool: 
https://www.mmad.info/MSS/mmss.htm


Here's an interview from 2011 (main language of the video is Basque, but 
interview is in English): https://youtu.be/b_OUhY16OhI


Marc


On Sun 4 Dec 2022, 19:26 David Stalling,  wrote:


Hi Thorsten,

Michael Williams is the author of the very interesting article about
stereo recording, The Stereophonic Zoom. Find it here:


https://www.fullcompass.com/common/files/22300-GraceDesignTheStereophonicZoombyMichaelWilliams.pdf

Best,
David


--
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On Sun 4 Dec 2022, 19:08 Thorsten Michels,  wrote:


Hi there!

Does anyone ever heard of a system described as "3 point XY"?

I attached a drawing to make it more understandable.

It seems to be a very special (aka very unknown) setup with three
supercardioids.
In the YT-Video https://www.youtube.com/watch?v=cA6MZPNVyZU, (only
available in German) the author claims, that this setup is based on
something Mr. Michael Williams has published.

Obiviously Mr. Google and I have some communication problems. He wont
show we any information about this.
Does someone of the great audiance has any information available by any
chance? If so, would you please share it with me?

I will give it a try next weekend, but it would be nice, if someone
could tell me more details in advance.

Thank you very much in advance, take care and stay healthy!


Cheers

Thorsten

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Re: [Sursound] 3 point XY - Anyone ever heard about this?

[David Stalling]

PS I don't think the 3 point XY technique is mentioned in the article but
just to give you a starting point for digging further.

On Sun 4 Dec 2022, 19:26 David Stalling,  wrote:

> Hi Thorsten,
>
> Michael Williams is the author of the very interesting article about
> stereo recording, The Stereophonic Zoom. Find it here:
>
>
> https://www.fullcompass.com/common/files/22300-GraceDesignTheStereophonicZoombyMichaelWilliams.pdf
>
> Best,
> David
>
>
> --
> Web: linktr.ee/davidstalling
>
> On Sun 4 Dec 2022, 19:08 Thorsten Michels,  wrote:
>
>> Hi there!
>>
>> Does anyone ever heard of a system described as "3 point XY"?
>>
>> I attached a drawing to make it more understandable.
>>
>> It seems to be a very special (aka very unknown) setup with three
>> supercardioids.
>> In the YT-Video https://www.youtube.com/watch?v=cA6MZPNVyZU, (only
>> available in German) the author claims, that this setup is based on
>> something Mr. Michael Williams has published.
>>
>> Obiviously Mr. Google and I have some communication problems. He wont
>> show we any information about this.
>> Does someone of the great audiance has any information available by any
>> chance? If so, would you please share it with me?
>>
>> I will give it a try next weekend, but it would be nice, if someone
>> could tell me more details in advance.
>>
>> Thank you very much in advance, take care and stay healthy!
>>
>>
>> Cheers
>>
>> Thorsten
>>
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>> Size: 215015 bytes
>> Desc: not available
>> URL: <
>> https://mail.music.vt.edu/mailman/private/sursound/attachments/20221204/8fc66278/attachment.png
>> >
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>>
>
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Re: [Sursound] 3 point XY - Anyone ever heard about this?

[David Stalling]

Hi Thorsten,

Michael Williams is the author of the very interesting article about stereo
recording, The Stereophonic Zoom. Find it here:

https://www.fullcompass.com/common/files/22300-GraceDesignTheStereophonicZoombyMichaelWilliams.pdf

Best,
David


--
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On Sun 4 Dec 2022, 19:08 Thorsten Michels,  wrote:

> Hi there!
>
> Does anyone ever heard of a system described as "3 point XY"?
>
> I attached a drawing to make it more understandable.
>
> It seems to be a very special (aka very unknown) setup with three
> supercardioids.
> In the YT-Video https://www.youtube.com/watch?v=cA6MZPNVyZU, (only
> available in German) the author claims, that this setup is based on
> something Mr. Michael Williams has published.
>
> Obiviously Mr. Google and I have some communication problems. He wont
> show we any information about this.
> Does someone of the great audiance has any information available by any
> chance? If so, would you please share it with me?
>
> I will give it a try next weekend, but it would be nice, if someone
> could tell me more details in advance.
>
> Thank you very much in advance, take care and stay healthy!
>
>
> Cheers
>
> Thorsten
>
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> Desc: not available
> URL: <
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> >
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[Sursound] 3 point XY - Anyone ever heard about this?

[Thorsten Michels]

Hi there!

Does anyone ever heard of a system described as "3 point XY"?

I attached a drawing to make it more understandable.

It seems to be a very special (aka very unknown) setup with three 
supercardioids.
In the YT-Video https://www.youtube.com/watch?v=cA6MZPNVyZU, (only 
available in German) the author claims, that this setup is based on 
something Mr. Michael Williams has published.


Obiviously Mr. Google and I have some communication problems. He wont 
show we any information about this.
Does someone of the great audiance has any information available by any 
chance? If so, would you please share it with me?


I will give it a try next weekend, but it would be nice, if someone 
could tell me more details in advance.


Thank you very much in advance, take care and stay healthy!


Cheers

Thorsten

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