Re: [Sursound] New filter

[Ralph Glasgal]

David's new crosstalk cancelling impulse response filter is a valuable addition 
to the large library of crosstalk cancelling gizmos now available.  I just used 
it with Waves IR-L (under AudioMulch) for the front speakers and RACE  (via 
TacT) for the rears, playing just ordinary stereo CDs, and I think this is the 
best four speaker wide stage and presence effect I have heard yet.  There must 
be some psychoacoustic advantage to using two completely different algorithms 
front and rear as compared to just using two different settings for RACE.  
There is also the difference in latency between the two processes and that 
may be a part of the reason.  Maybe some kind of averaging effect.  But the 
imaging at the 90 degree sides was exemplary and full bodied and mono front and 
center.  RACE operates over the full bandwidth although it does nothing useful 
XTC-wise in the very low bass or the very high treble. David's operates only 
between 200 and 1000 Hz
 so perhaps the combination is beneficial.  For just plain frontal stereo with 
two speakers it is a trouble free delight with a non-critical sweet area at 
least with my speakers so far.
 
If you lose DW's message, his links and description will be available on the 
Ambio website shortly.
 
Thanks to help from around the world, one can have the following versions of 
Ambio-like crosstalk cancellation (i.e. no HRTF's used, fully 
recursive,  smaller speaker angle, 4.0 capability etc.)
 
Hardware Components (no PC required)
Transcoders for Java
VST plugins
Raw Impulse Responses for convolvers
Apps for the iPad
Mechanical barriers
 
More coming I hope.  We still need a 3D program for steering concert hall 
ambience derived from Hall IRs to an arbitrary number of ambience surround 
speakers.  But I have to say that almost all Ambio users are only into movies, 
games, and video so a Domestic Concert Hall is not on many lists.  Probably 3D 
sound (via four speakers i.e. two Ambiodipoles) for 3D video may be 
the ultimate most popular use. 
 
Ralph Glasgal
www.ambiophonics.org

From: dw 
To: Surround Sound discussion group 
Sent: Sunday, May 29, 2011 11:13 AM
Subject: [Sursound] New filter



Free Ambiophonic "stereo-dipole" type crosstalk cancelling filter.

For 3 sample delay @ 44100. Speaker angle ~ ± 7.5 degrees.

Tested with Jawbone Jambox @ ~40 cm. distance.

http://www.wareing77.plus.com/Filters/

Sorry for the repost, but my computer thought it was Febuary the last time..

David Wareing.
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Re: [Sursound] New filter

[Stefan Schreiber]

Ralph Glasgal wrote:

David's new crosstalk cancelling impulse response filter is a valuable addition to the large library of crosstalk cancelling gizmos now available.  


...



Thanks to help from around the world, one can have the following versions of 
Ambio-like crosstalk cancellation (i.e. no HRTF's used, fully recursive,  
smaller speaker angle, 4.0 capability etc.)

Hardware Components (no PC required)
Transcoders for Java
VST plugins
Raw Impulse Responses for convolvers
Apps for the iPad
Mechanical barriers

More coming I hope.  We still need a 3D program for steering concert hall ambience derived from Hall IRs to an arbitrary number of ambience surround speakers.  But I have to say that almost all Ambio users are only into movies, games, and video so a Domestic Concert Hall is not on many lists.  Probably 3D sound (via four speakers i.e. two Ambiodipoles) for 3D video may be the ultimate most popular use. 


Ralph Glasgal
www.ambiophonics.org
 



Would you not need at least six speakes (or three Ambiodipoles) for 
proper 3D sound, in Ambiophonic context? (One speaker-pair would have to 
be fixed above head, at least in my current interpretation.)


Thanks for clarifications

Stefan Schreiber


From: dw 
To: Surround Sound discussion group 
Sent: Sunday, May 29, 2011 11:13 AM
Subject: [Sursound] New filter



Free Ambiophonic "stereo-dipole" type crosstalk cancelling filter.

For 3 sample delay @ 44100. Speaker angle ~ ± 7.5 degrees.

Tested with Jawbone Jambox @ ~40 cm. distance.

http://www.wareing77.plus.com/Filters/

Sorry for the repost, but my computer thought it was Febuary the last time..

David Wareing.

 



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Re: [Sursound] New filter

[Fons Adriaensen]

On Mon, May 30, 2011 at 07:49:19AM -0700, Ralph Glasgal wrote:

> RACE operates over the full bandwidth although it does
> nothing useful XTC-wise in the very low bass or the very
> high treble. David's operates only between 200 and 1000 Hz.

I wonder what makes you write the latter. Simple measurement
shows quite a different picture.

Ciao,

-- 
FA

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Re: [Sursound] New filter

[dw]

On 30/05/2011 16:18, Fons Adriaensen wrote:

On Mon, May 30, 2011 at 07:49:19AM -0700, Ralph Glasgal wrote:


RACE operates over the full bandwidth although it does
nothing useful XTC-wise in the very low bass or the very
high treble. David's operates only between 200 and 1000 Hz.

I wonder what makes you write the latter. Simple measurement
shows quite a different picture.

Ciao,

I think Ralph may have misunderstood my terse emails. There are indeed 
crossovers at 200Hz and 1kHz. The details I will keep to myself, but you 
can get the general picture from:

http://www.wareing77.plus.com/Filters/Frequency_response_DW3.png


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Re: [Sursound] New filter

[Fons Adriaensen]

On Mon, May 30, 2011 at 05:08:41PM +0100, dw wrote:
> On 30/05/2011 16:18, Fons Adriaensen wrote:
>> On Mon, May 30, 2011 at 07:49:19AM -0700, Ralph Glasgal wrote:
>>
>>> RACE operates over the full bandwidth although it does
>>> nothing useful XTC-wise in the very low bass or the very
>>> high treble. David's operates only between 200 and 1000 Hz.
>> I wonder what makes you write the latter. Simple measurement
>> shows quite a different picture.
>>
>> Ciao,
>>
> I think Ralph may have misunderstood my terse emails. There are indeed  
> crossovers at 200Hz and 1kHz. The details I will keep to myself, but you  
> can get the general picture from:
> http://www.wareing77.plus.com/Filters/Frequency_response_DW3.png

Thanks for the confirmation. Two questions:

1. What is the purpose (if any) of the rather sharp dip
at 130 Hz in the cross-channel response ?

2. Would you give me permission to add your filter (and a 
48 kHz version) to the set supplied with jconvolver, with
proper attribution in the config file of course ?


Ciao,

-- 
FA

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Re: [Sursound] New filter

[dw]

On 30/05/2011 17:45, Fons Adriaensen wrote:

On Mon, May 30, 2011 at 05:08:41PM +0100, dw wrote:

On 30/05/2011 16:18, Fons Adriaensen wrote:

On Mon, May 30, 2011 at 07:49:19AM -0700, Ralph Glasgal wrote:


RACE operates over the full bandwidth although it does
nothing useful XTC-wise in the very low bass or the very
high treble. David's operates only between 200 and 1000 Hz.

I wonder what makes you write the latter. Simple measurement
shows quite a different picture.

Ciao,


I think Ralph may have misunderstood my terse emails. There are indeed
crossovers at 200Hz and 1kHz. The details I will keep to myself, but you
can get the general picture from:
http://www.wareing77.plus.com/Filters/Frequency_response_DW3.png

Thanks for the confirmation. Two questions:

1. What is the purpose (if any) of the rather sharp dip
at 130 Hz in the cross-channel response ?


It is the point at which it goes through zero as the phase goes through 
180 degrees.



2. Would you give me permission to add your filter (and a
48 kHz version) to the set supplied with jconvolver, with
proper attribution in the config file of course ?

Certainly. John Pavel has already done so for his convolver. 
http://convolver.sourceforge.net/configegs.html

I will add a link and config file for your convolver to /Filters.

Ciao,



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Re: [Sursound] Book on Michael Gerzon, audio pioneer and music recordist

[Paul Hodges]

--On 29 May 2011 09:41 + Richard Lee  wrote:


Steve Thornton is selling a coffee table book based on his encyclopediac
photographic record of OUTRS and other stuff.

Be the first to brag a limited edition hardcover link which goes back to
A.  Blumlein   Loadsa stuff on the rise & fall of quad, surround and
the  early history of Ambisonics, the Soundfield Mic ...


I would like to assure people that this book is beautifully printed and 
made, and the photographs (which are the basis of the book) come up even 
better than on the website.


Paul

--
Paul Hodges


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Re: [Sursound] New filter

[Fons Adriaensen]

On Mon, May 30, 2011 at 05:54:12PM +0100, dw wrote:

> It is the point at which it goes through zero as the phase goes through  
> 180 degrees.

Now I'm puzzled... That frequency corresponds to a  wavelength
of 2.6 meter, which is more than 10 times the size of a human
head. Which phase (or phase difference) goes through 180 degrees
at that frequency ?

Ciao,

-- 
FA

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Re: [Sursound] New filter

[dw]

On 30/05/2011 19:01, Fons Adriaensen wrote:

On Mon, May 30, 2011 at 05:54:12PM +0100, dw wrote:


It is the point at which it goes through zero as the phase goes through
180 degrees.

Now I'm puzzled... That frequency corresponds to a  wavelength
of 2.6 meter, which is more than 10 times the size of a human
head. Which phase (or phase difference) goes through 180 degrees
at that frequency ?

Ciao,

For Xtalk cancellation, the intention is to get the blue line intended 
for the contralateral ear (far, right ear) to cancel as far as possible 
(by being equal and opposite) the green line intended for the near, left 
ear, when both reach the right ear (mauve line) after the 3 sample delay 
and attenuation of the head. When these two same signals vector sum at 
the near ear the result should be a flat frequency response (top yellow 
line). Of course this is only a computer model of the head, so it is not 
likely to be quite as good in practice! At low frequencies this 
corresponds to the signals being (nearly) 180 out of phase at the 
speakers until I give up on flogging the speakers to death and swap to 
driving them in phase. The above only applies to right or left channels 
on their own. If the source is mono everything cancels during 
convolution and the speaker drives are in phase and at a lower level 
(lower yellow line).

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Re: [Sursound] New filter

[dw]

On 30/05/2011 15:49, Ralph Glasgal wrote:

David's new crosstalk cancelling impulse response filter is a valuable addition 
to the large library of crosstalk cancelling gizmos now available.  I just used 
it with Waves IR-L (under AudioMulch) for the front speakers and RACE  (via 
TacT) for the rears, playing just ordinary stereo CDs, and I think this is the 
best four speaker wide stage and presence effect I have heard yet.


That's the bad news. The good news is that it seems to get better the 
more you listen, as if the brain is learning a new head.


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Re: [Sursound] New filter

[Fons Adriaensen]

On Mon, May 30, 2011 at 07:32:52PM +0100, dw wrote:

> At low frequencies this  
> corresponds to the signals being (nearly) 180 out of phase at the  
> speakers until I give up on flogging the speakers to death and swap
> to driving them in phase.

I understand. As frequency goes down more and more energy is
wasted driving the two speakers out of phase to deliver the
right signals at the ears. There has to be a limit to this.

But it's the 'swap to driving them in phase' that puzzels me.
Why no just keep the difference gain at some maximum value, or
even let it drop off as frequency goes down, instead of cross-
fading to driving the speakers in phase ? 

Ciao,

-- 
FA

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Re: [Sursound] New filter

[dw]

On 30/05/2011 22:28, Fons Adriaensen wrote:

On Mon, May 30, 2011 at 07:32:52PM +0100, dw wrote:


At low frequencies this
corresponds to the signals being (nearly) 180 out of phase at the
speakers until I give up on flogging the speakers to death and swap
to driving them in phase.

I understand. As frequency goes down more and more energy is
wasted driving the two speakers out of phase to deliver the
right signals at the ears. There has to be a limit to this.

But it's the 'swap to driving them in phase' that puzzels me.
Why no just keep the difference gain at some maximum value, or
even let it drop off as frequency goes down, instead of cross-
fading to driving the speakers in phase ?

Ciao,

There is a useful 6dB gain to be had over driving just one speaker, let 
alone driving two in antiphase. Quite useful to have even if you don't 
have 1" woofers like me! I've already had Ralph complaining that 
Choueiri filters play louder!

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Re: [Sursound] New filter

[Ralph Glasgal]

One needs to define what you want from height speakers.  For concert hall 
ambience if one has an impulse response of the hall that is 3D and thus 
includes the height vectors, you can simply use elevated speakers in any number 
you like and feed them the overhead reflections derived from convolving that 
part of the hall impulse response.  I do this since I have built a room with 
two very high balconies where the elevated surround speakers can sit.  But 
height ambience is not all it is cracked up to be.  Reflections from the 
ceiling in a concert hall are essentially mono with a high IACC and so are not 
very interesting to the brain.  So it is normally better, if on a limited 
budget, to concentrate on ambience speakers at the sides and rear.

 
Direct sound height is another matter and normally does not apply to music.  
The Panambiophone can make front, rear and overhead pairs each isolated from 
one another.  If you play the height pair crosstalk cancelled through two 
elevated speakers (picture of this in my AES RACE paper) you do get a nice 
elevated stage normally placed to the front.  One could also hear direct sound 
sources between the horizontal plane and the elevated one which was a surprise 
to me.  But there are few heavenly choirs to record and so little has been done 
with this.  I think it is only of use for games and movies.  For these you 
would likely want both front and rear elevated XTC pairs and you can then 
synthesize the eight channels a process which is now normal for games and 
movies which almost never see a microphone or at least one that is not mono 
ready for panning.
 
Ralph Glasgal
www.ambiophonics.org
 
 
 
From: Stefan Schreiber 
To: Surround Sound discussion group 
Sent: Monday, May 30, 2011 11:10 AM
Subject: Re: [Sursound] New filter

Would you not need at least six speakes (or three Ambiodipoles) for 
proper 3D sound, in Ambiophonic context? (One speaker-pair would have to 
be fixed above head, at least in my current interpretation.)

Thanks for clarifications

Stefan Schreiber
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