BACCH, Ambiophonics, etc

[AJ Soundfield]

2 hours ago, Ralph Glasgal said:

I have written some million words on this topic but nothing would please me more than to answer any questions on Ambiophonic principles or psychoacoustics.  Do you have a specific topic in mind?

Yes, here you said about the Johnston AES paper: Almost every word in this is either incorrect, self serving or misleading.

The facts about both hearing perception and soundfields are laid out in detail above.

Please correct all the errors.

 

Quote

 I hope the points I have made were all backed by listening panel tests

I have read 3 random papers so far on your site, not a single one contained any listening tests whatsoever.

Please link the specific papers with listening test actually performed, thanks.

[Ralph Glasgal]

16 hours ago, AJ Soundfield said:

Yes, here you said about the Johnston AES paper: Almost every word in this is either incorrect, self serving or misleading.

The facts about both hearing perception and soundfields are laid out in detail above.

Please correct all the errors.

 

I have read 3 random papers so far on your site, not a single one contained any listening tests whatsoever.

Please link the specific papers with listening test actually performed, thanks.

http://www.ambiophonics.org/papers/AES136IRIS.pdf

http://steinhardt.nyu.edu/scmsAdmin/media/users/dtv206/Thesis_TsaiYi_Final.pdf

http://www.ambiophonics.org/papers/AES123NYC0710.html

The listening test result below is Robin Miller is not on my site, but this is a result from 2007, so we do betternow.

Also the above have frequency response tests at the ears of listeners, not just their subjective opinions.

I am of course hoping that Universities and companies will confirm the results.  There are of course the non peer reviewed which I am listing here. These at akin to all those reviews of amplifiers and speakers that also were not done with listening panels or were peer reviewed.

http://www.lowbeats.de/test-software-app-xivero-amtra-und-amtra-play/

 

 

  

[Ralph Glasgal]

21 hours ago, AJ Soundfield said:

Yes, here you said about the Johnston AES paper: Almost every word in this is either incorrect, self serving or misleading.

The facts about both hearing perception and soundfields are laid out in detail above.

Please correct all the errors.

 

I have read 3 random papers so far on your site, not a single one contained any listening tests whatsoever.

Please link the specific papers with listening test actually performed, thanks.

Some kind of mixup.  I thought my comments were in reference to some advertising comments from the BACCH people.  Not anything from Clark who has visited me and enjoyed 78 RPM mono more than any ordinary stereo.

 

[AJ Soundfield]

1 hour ago, Ralph Glasgal said:

Some kind of mixup.  I thought my comments were in reference to some advertising comments from the BACCH people.  Not anything from Clark who has visited me and enjoyed 78 RPM mono more than any ordinary stereo.

 

Fair enough. The link quoted was J Johnston. Onward..

 

The first 2 papers linked were laptop speakers related, I skipped those.

The last was of interest http://www.ambiophonics.org/papers/AES123NYC0710.html included ,measurements, thanks.

Ok, here are mine. Speakers are Infinity Primus 152 (only cosmetic different to 150) https://www.stereophile.com/content/infinity-primus-150-loudspeaker-measurements

7' stereo 60 L, R and L&R sum, mic about 3" off center to left "sweet spot" head position.

 

 

 

[AJ Soundfield]

7' Ambio20, (MiniDSP) same mic position

4.5db parametric boost centered at 103hz done "by ear" during set up. RACE at default setting

 

[AJ Soundfield]

From other thread

2 hours ago, Ralph Glasgal said:

Yes.  The widest stage is achieved when one is on the center line between the speakers.  This is like stereo except that one can move forward and back a lot more.  In most stereo systems if you move to the side you localize to one speaker. 

[AJ Soundfield]

For some reason the formatting here does weird stuff.

 

Yes, "most". But I have posted numerous times that this is false for all, as "wide" sweet spot stereo has been possible for decades, that does not collapse to nearest speaker.

[AJ Soundfield]

Quote

 

In Ambio if you move around you still hear both channels almost anywhere in the room.  You can also nod, lean, and rotate you head like stereo.  But yes, the sweet area is not like Wavefield Synthesis or the head tracking ones.  Of course, someone will add head tracking or similar to RACE.  But RACE was meant for home listening and relative simplicity, like stereo.  Yes RACE is not for every listening application  but what is?

 

 

 

 

Ambio/Binuaral cross cancel schemes are nothing like stereo, since stereo is capable of a much wider sweet spot. Demonstrable. This is false equivalence.

 

 

Quote

 

Since no center speaker is ever needed, you can put a TV set between the speakers.  On the home page and below there is a picture of a such a system with a projector. 

 

That screen is in front of speakers!! Unless acoustically transparent, that has to be very audible. Once again, the narrow sweet spot problem arises, more dramatically so vs a true 5ch ITU based movie system

[AJ Soundfield]

Quote

Ralph Glasgal said

 

No.  But in stereo there at a lot of reasons why moving might change the bass response.  The basic problem is that when both ears hear both speakers bass is doubled when there is bass in both speakers.  The exact amount of doubling depends on a lot of things so that a problem.  With XTC there is no doubling as long as you have good XTC.  So it matters a lot less where you are in the room.  But from 90 Hz down all bets are off. 

I'm starting to understand the odd Ambio FR shape at bit better. So there is no compensation for whether a pressure or velocity source is used. This means the user must be able to measure.

 

Quote

Stereo and XTC are no different when it comes to very low bass.

False. The Ambio speaker close spacing renders any low bass spatial info moot.

Lateralisation is possible down to frequencies as low as 40hz, but that also depends on many factors. There is no chance with the 2 front speakers at Ambio 20

https://secure.aes.org/forum/pubs/conferences/?elib=17270

http://www.acoustics.asn.au/conference_proceedings/AAS2008/papers/p47.pdf

http://www.aes.org/e-lib/browse.cfm?elib=13358

[semente]

On 3 July 2017 at 0:26 AM, AJ Soundfield said:

7' Ambio20, (MiniDSP) same mic position

4.5db parametric boost centered at 103hz done "by ear" during set up. RACE at default setting

 

 

That >5dB peak in the "presence" region must be quite noticeable and above that the whole band is shelved a couple of dB.

I bet there's lot's of "detail" and "air" and "presence".

 

How weird does it sound tone-wise?

 

Is there a way to measure what's happening with phase?

[AJ Soundfield]

7 minutes ago, semente said:

 

That >5dB peak in the "presence" region must be quite noticeable and above that the whole band is shelved a couple of dB.

I bet there's lot's of "detail" and "air" and "presence".

 

How weird does it sound tone-wise?

 

Is there a way to measure what's happening with phase?

Here is my initial impression immediately after setup just to hear it https://www.computeraudiophile.com/forums/topic/32987-bacch-ambiophonics-etc/

No measurements until later. Independence day today, so time constrained but I plan to reEQ with the parametrics in the Ambio plug in. The peak is fairly narrow Q, so not quite as dramatic as it looks, though with certain sounds it will impact. Much like my experiences with SDA and Carver, there is hit and miss, some recordings sound nicely expanded, others have an odd quality. Its very early in the game to make any conclusions. I will have to do a lot more reading of Ralphs site regarding setup, RACE etc, as the minidsp site is lacking. I'm browsing many sites and pics to see what others did, but unfortunately few with any measurements.

I did toe out the speakers slightly based on a photo I came across on a site with jihadist fervor for ambio and there are many other examples that can be studied for placement, etc. I don't have any "treatments" in the iso..excuse, living room, just "furnishings" etc.

Plan to post some updates in the week, maybe make an ambio demo during a future club meet.

[Ralph Glasgal]

On ‎7‎/‎2‎/‎2017 at 7:24 PM, AJ Soundfield said:

Fair enough. The link quoted was J Johnston. Onward..

 

The first 2 papers linked were laptop speakers related, I skipped those.

The last was of interest http://www.ambiophonics.org/papers/AES123NYC0710.html included ,measurements, thanks.

Ok, here are mine. Speakers are Infinity Primus 152 (only cosmetic different to 150) https://www.stereophile.com/content/infinity-primus-150-loudspeaker-measurements

7' stereo 60 L, R and L&R sum, mic about 3" off center to left "sweet spot" head position.

 

 

 

It is true that laptop speakers were used to test Ambidio but the thesis also includes frequency response comparisons using normal floor standing speakers. See Figure five in the AES paper. I would also think it a bit arbitrary to just assume that the preference results would be different if speakers that you prefer were used.  There are at least hundreds of Ambiophonic systems out there using a variety of speakers so that cannot be a serious issue.  I wish were so rich that I could do listening panel tests with each speaker on the market.   But with any speaker type and any one listener with a mic in his ear you can show that Ambio is much flatter where it counts than stereo.  This is true for all speaker types and human heads.  

[Ralph Glasgal]

13 hours ago, AJ Soundfield said:

I'm starting to understand the odd Ambio FR shape at bit better. So there is no compensation for whether a pressure or velocity source is used. This means the user must be able to measure.

 

False. The Ambio speaker close spacing renders any low bass spatial info moot.

Lateralisation is possible down to frequencies as low as 40hz, but that also depends on many factors. There is no chance with the 2 front speakers at Ambio 20

https://secure.aes.org/forum/pubs/conferences/?elib=17270

http://www.acoustics.asn.au/conference_proceedings/AAS2008/papers/p47.pdf

http://www.aes.org/e-lib/browse.cfm?elib=13358

I meant that low bass is a problem for Ambio and stereo in general.  Yes the speaker spacing may make a difference good or bad.  The only real important difference is that in the low bass energy is not doubled in error for recordings that have central bass.  Otherwise I know no more about subwoofers or standing waves than anyone else.

[Ralph Glasgal]

On ‎7‎/‎2‎/‎2017 at 8:16 PM, AJ Soundfield said:

For some reason the formatting here does weird stuff.

 

Yes, "most". But I have posted numerous times that this is false for all, as "wide" sweet spot stereo has been possible for decades, that does not collapse to nearest speaker.

Yes Ben Bauer of CBS claimed a wider sweet area in the last century.  It is a matter of degree.  It is nice that with Ambio you don't have to worry about hearing both channels anywhere or having special speakers.  Even with the larger sweet area type speakers eventually it does collapse to one speaker and there are issues with localization cue distortion.  The stereo effect is like an optical effect in which the depth part is fragile evn if  resolution, color, contrast, aspect ration, etc. are ideal but when you move your eyes maybe the color fringes, and objects flatten. 

[AJ Soundfield]

4 minutes ago, Ralph Glasgal said:

The only real important difference is that in the low bass energy is not doubled in error for recordings that have central bass. 

Ralph, thanks for your replies here. The other thread was for MCH in general, not a referendum on Ambio as a proselytizer turned it into.

The issue I have with your quote is that studio recordings are monitored with stereo loudspeakers. As such, the spectral shaping in the bass should be "correct" for stereophonic onset response ("direct" sound prior to modal interaction, etc). The doubling from 2 source correlation at LF is already accounted for.

 

Quote

Otherwise I know no more about subwoofers or standing waves than anyone else.

One of the reasons I used small bookshelfs is some anticipation that the bass could not be cross cancelled and would loose spatial impression. Using widely spaced (w/without decorrelation) subs could help there..when time permits.

Any thoughts on 2k peak?

[Ralph Glasgal]

On ‎7‎/‎2‎/‎2017 at 8:22 PM, AJ Soundfield said:

 

That screen is in front of speakers!! Unless acoustically transparent, that has to be very audible. Once again, the narrow sweet spot problem arises, more dramatically so vs a true 5ch ITU based movie system

Yes.  It was a great relief to find out that it made absolutely no difference in the wide stage and the flat response.  Those ESLs are very tall and are line sources.  When you sit down you hear some lines that are long and a few that are short.  Also the screen really is not opaque to sound.  Subjectively with a movie like Avatar the stage extends out to the far sides and with the rears going in a full circle with just four speakers!

[AJ Soundfield]

3 minutes ago, Ralph Glasgal said:

Yes Ben Bauer of CBS claimed a wider sweet area in the last century.  It is a matter of degree. 

I was referring to the work of Davies et al http://www.linkwitzlab.com/Links/Optimized-listening-area-Davies.pdf

It is more than a "claim"

[semente]

Just now, Ralph Glasgal said:

Yes.  It was a great relief to find out that it made absolutely no difference in the wide stage and the flat response.  Those ESLs are very tall and are line sources.  When you sit down you hear some lines that are long and a few that are short.  Also the screen really is not opaque to sound.  Subjectively with a movie like Avatar the stage extends out to the far sides and with the rears going in a full circle with just four speakers!

 

One would think, just by looking at the photo, that the screen between listener and sound sources would actually increase the sound-from-the-sides effect.

[AJ Soundfield]

Ralph have a happy and safe 4th, time to fire up the grill 

[Ralph Glasgal]

2 hours ago, AJ Soundfield said:

Ralph have a happy and safe 4th, time to fire up the grill 

Thanks and same to you.  I have enjoyed your posts.

[Ralph Glasgal]

2 hours ago, semente said:

 

One would think, just by looking at the photo, that the screen between listener and sound sources would actually increase the sound-from-the-sides effect.

As far as I can tell no sound is diverted to any reflecting surface that impacts on the listening area.  But I have a panel that covers the front surface of the screen for music so that rear speakers do not reflect off it.  Also it is quite high and so sends sound into the ether.  Also reflections have a longer time delay so they are easy to work with and integrate into the concert hall you are fabricating.  (Nothing to do withf movies of course)

[semente]

1 minute ago, Ralph Glasgal said:

As far as I can tell no sound is diverted to any reflecting surface that impacts on the listening area.  But I have a panel that covers the front surface of the screen for music so that rear speakers do not reflect off it.  Also it is quite high and so sends sound into the ether.  Also reflections have a longer time delay so they are easy to work with and integrate into the concert hall you are fabricating.  (Nothing to do withf movies of course)

 

I fail to understand how you can ensure  correct frequency response in the listening spot if you have something blocking direct radiation.

[Ralph Glasgal]

2 hours ago, AJ Soundfield said:

I was referring to the work of Davies et al http://www.linkwitzlab.com/Links/Optimized-listening-area-Davies.pdf

It is more than a "claim"

Make that substantiated claims in both cases.  Still no matter how wide the sweet area, the stage width is still at 60 degrees or so for standard stereo regardless of the speaker polar pattern.

[Ralph Glasgal]

2 hours ago, AJ Soundfield said:

Any thoughts on 2k peak?

If you get an audible peak in Ambio you can just use the controls to either not use race at a frequency above say 1900 Hz or change the delay and attenuation controls to do a more accurate cancellation.  Most such peaks are inaudible and not as numerous as the ones in stereo.  The comb filtering in every stereo system causes alternating 6 dB peaks and deeper dips.  Indeed the better the system the worse the frequency response is at the ear drum, of course.  There are also the other stereo distortions in level and time that nobody ever talks about.  If the peak is caused by a room reflection then it is likely inaudible due to timing factors.  There are lots of peaks and dips in concert halls but they just add to the realism of the soundfield and do not effect localization or the frontal stage response.

[semente]

1 minute ago, Ralph Glasgal said:

There are lots of peaks and dips in concert halls but they just add to the realism of the soundfield and do not effect localization or the frontal stage response.

 

It makes no sense to compare live ambience with reproduction artifacts.

The peaks and dips in concert halls don't add to the realism, they are the reality; I find this a very serious misconception.

If they were registered in the recording they should be presented in the reproduction.