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Envelopment: Toole, Multichannel, Binaural

Scott Borduin

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#41
There were 2 events I attended although many other speakers (people) used the system for demonstrations. This is what Morten Lindberg tells me about the system:
1. Source was our original production files at 24/352.8 from a Pyramix workstation thru a HAPI converter over Ravenna AoIP.
2. For this second session with Dan we also used Pure Audio Blu-ray thru a StormAudio ISP 3D.16 ELITE unfolding 9.1 at 24/96: www.aes.org/events/143/spatialaudio/?ID=5814
3. Loudspeakers were PMC IB2S XBD-A: https://pmc-speakers.com/products/professional/active/ib2s-xbd
+ for the heights: PMC twotwo.6 https://pmc-speakers.com/products/professional/active/twotwo6
Thanks Kal, interesting that you were impressed with the results even with what is a base level 9.1 Auro/Atmos configuration.

Holy cow, I just Googled those PMC speakers and saw a price of $69K per pair?! I bet with careful shopping I could put together a whole system for that :)

Scott
 

Fitzcaraldo215

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#42
Well, if you've ever heard Dark Side of the Moon in 5.1, you've heard how surround effects can create interesting artistic impressions in pop music independent of enhancing any sense of performance space.



I used the word envelopment because Toole uses it, and because it is apparently a term commonly used in describing concert hall quality. But I get what you're saying - I don't sit in Schnitzer hall and think I'm being enveloped.



I found the link to Toole's AVS forum post on this: https://tinyurl.com/y7gflkjl . Toole is pretty knowledgable about theater sound, and is not impressed that the ITU standards are based on much in particular. And he seems to think that placing sides at +-60 is best for music, regardless of whether there are additional speakers in the system. His thoughts about 9.1 are for systems which need to serve up HT effects as well as music. If you're happy with the results you get from your setup, of course no need to change. For those of us who never got 5.1/7.1 to sound exactly natural, simple experiments with relocating side speakers are easy and free!
Yup, I have DOTSM on SACD, and I have heard it perhaps too many times. Yes, it is very striking, and it illustrates the simplest, most elementary use of Mch. It may well be the biggest selling SACD ever. But, interest in Mch rock has not really ever caught fire. I have many such re-panned rock releases, but I think the novelty wears off, myself.

My favorite Mch rock SACDs are Allman Bros. Live at the Fillmore East and Eat a Peach, the latter featuring the awesome 30+ minute Mountain Jam, both when the incredible Duane Allman was still with us. The band lived on but was never as great after his tragic death not too long after. These albums are well done from a close in audience perspective, as I prefer it, from Quad-era masters. They deliver a great sense of a live concert. I enjoyed these albums often with my daughter and friends in stereo in the seventies. So, they also have great sentimental value. The sound was never better than on these SACDs.

Yeah, I know, "envelopment" and "surround sound" are not going away, much as I dislike the terms. Yup, the sound of live is what it is, a complete, exquisite whole. We don't think of being "enveloped" or "surrounded", though of course we are by hall reflections in the audience.

Yes, I admire and respect Toole, especially after reading his latest volume. Audyssey had tried a proprietary +- 60 synthesis scheme overlayed on regular Mch, but it appeared to be a commercial dud. I never tried it. Currently, 3D "immersive" schemes seem to garner much more attention without a +- 60 synthesizer. Yawn. I'll be happy to take plain old 5.0/.1 discrete, thanks, unless there is a respectable and viable stream of new, discrete recordings using more channels in a standardized way.

Happy listening!
 

Scott Borduin

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#43
Yes, I admire and respect Toole, especially after reading his latest volume. Audyssey had tried a proprietary +- 60 synthesis scheme overlayed on regular Mch, but it appeared to be a commercial dud. I never tried it. Currently, 3D "immersive" schemes seem to garner much more attention without a +- 60 synthesizer.
Just to be clear for the other readers of the thread, what Toole proposes is not necessarily synthesizing the 60 degree speaker channels, he simply proposes to locate the side speakers there instead of the usual 90-110 degrees. This is not as crazy as it sounds, because on an acoustic recording the information in those channels is largely decorrelated reflective and diffusive sound with little directional dependency. Only if one wants to keep the standard side speaker location for rearward effects does he propose synthesizing the 60 degree channels as delayed versions of the side channels.
 

Fitzcaraldo215

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#44
Just to be clear for the other readers of the thread, what Toole proposes is not necessarily synthesizing the 60 degree speaker channels, he simply proposes to locate the side speakers there instead of the usual 90-110 degrees. This is not as crazy as it sounds, because on an acoustic recording the information in those channels is largely decorrelated reflective and diffusive sound with little directional dependency. Only if one wants to keep the standard side speaker location for rearward effects does he propose synthesizing the 60 degree channels as delayed versions of the side channels.
Still sounds crazy to me. I don't believe that the surround channel signal in discrete ITU recordings is any old decorrelated reflective and diffuse sound which can be arbitrarily moved to any other location. Yes, it contains that, but I believe in a specific way that interacts in a specic fashion with front and center channels, all assumed to be in a particular angular array. I just don't think the resulting phantom imaging can be accurate. Or, that the front soundstage can have the correct "pull" into the room, among other possible consequences on frontal image depth and width. Phantom images will be messed up, I believe, or at least not consistent with what was picked up by mikes in the hall.

I am not defending the almighty rightness of ITU, or dismissing Toole's theoretical criticisms of it. Recording engineers I know, as well as Sony/Phillips and the team of engineers who worked up the standard think it is pretty good and pretty workable. Record labels have also evaluated it and invested considerable sums in recordings and equipment predicated on it. Maybe they all just brain-dead lemmings? But, it has been used for SACD for approaching 20 years. I have heard no outcry of rage against it. And, speaker guy Toole has not made any commercial recordings using his idea or commercialized his scheme that I am aware of.

I am just suggesting that if the recording is miked that way, optimal playback will use the same spatial and angular configuration. It is similar to Blumlein stereo. If you do not use a 90 degree speaker array, you will still get music, but not as the mikes heard it and not at all with the same sense of space Blumlein is attempting to accurately preserve.

I think any evaluation of Mch should start by carefully adhering to known accepted standards, even if they have their critics. Adding supplementary +-60 to that array might be interesting, and it will have an effect, no doubt. Outright replacement of +- 110 with +- 60 will have a big effect. But, I would have a mental block about liking it because I think it is a distortion of the reality on the disc. But, try it and let us know.

Don't call it synthesis if you prefer. But, simple and non-algorithmic as it is, it is adding new sounds at a different location than the original. I prefer hearing the undistorted original. Same goes for my stereo listening, by the way. I much prefer listening to that in 2.0. Listening extensively to expansion schemes are interesting, but ultimately not better in my view and not "truer to the source."
 

Scott Borduin

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#45
I am not defending the almighty rightness of ITU, or dismissing Toole's theoretical criticisms of it. Recording engineers I know, as well as Sony/Phillips and the team of engineers who worked up the standard think it is pretty good and pretty workable. Record labels have also evaluated it and invested considerable sums in recordings and equipment predicated on it. Maybe they all just brain-dead lemmings? But, it has been used for SACD for approaching 20 years. I have heard no outcry of rage against it. And, speaker guy Toole has not made any commercial recordings using his idea or commercialized his scheme that I am aware of.
Hi Fitzcaraldo,

I think we agree more than we disagree, and I don't want to make this into a tempest in a teapot. I think we're approaching this from a different base of experience, and maybe somewhat different philosophy. You have way more experience with Mch than I do - and that is a base of empirical knowledge people like me want to tap into. What have you learned about recordings, equipment, setup, room treatments, etc? Were my variable experiences due to variables in the implementation? That's what I want to learn from.

At the same time, I'm aware that a lot of audio reproduction is not yet a science. In my profession, we often don't have the knowledge or time to understand the behavior of a particular system in detail, so we run intuitively guided experiments to figure it out and try to solve a problem quickly, even if we don't have a deep understanding of what's going on in the system. That's called "hacking" in the software world.

Reading the literature about audio reproduction, there are some things we have pretty well documented about the "black box" ear/brain system and its interaction with reproduction technology. The primacy of frequency response in loudspeakers, the subjective preferences of listeners in performance spaces, the basic strengths and weaknesses of stereo, etc. But there are also areas where we are just still hacking to a certain extent. How many channels, placed where, in what kind of listening environment, are necessary to recreate a near perfect illusion of reality? What are the factors preventing binaural from realizing its theoretical perfection? To name just the subjects of this thread.

Presuming we find answers to those questions for some listeners, will those answers be universal or listener-specific? We just don't have the body of controlled experiments to prove these things one way or another - not even close - so we're reduced to either trusting what we know and making that work as ideally as possible, or hacking to see if there's something better - and then trying to synthesize that bottom-up knowledge into a more foundational theory. In many ways, I'm just more of a hacker :)

Scott
 
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#47
My current stereo system is based on Sanders 10e electrostatics. I go back and forth between manual EQ below 500hz, and full correction with Acourate.
Really interesting write up Scott, although I'm not sure I'll ever take the plunge into multi-channel (8 active channels for stereo is enough complication for me :)) but I'm curious as to why you go back and forth between manual EQ and Acourate?
 

Scott Borduin

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#48
Really interesting write up Scott, although I'm not sure I'll ever take the plunge into multi-channel (8 active channels for stereo is enough complication for me :)) but I'm curious as to why you go back and forth between manual EQ and Acourate?
The electronic XO supplied with the Sanders is a DBX Venu 360 pro unit, which has built-in PEQ. I listened that way for a year, with EQ mostly below the transition region other than a bit of touch up on a broad, shallow upper midrange bump. Then I worked up an Acourate setup with software XO and full range correction. It sounds a bit different, but I'm not sure it's better. I can easily switch between the two using the zones capability in Roon.
 

Fitzcaraldo215

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#49
Hi Fitzcaraldo,

I think we agree more than we disagree, and I don't want to make this into a tempest in a teapot. I think we're approaching this from a different base of experience, and maybe somewhat different philosophy. You have way more experience with Mch than I do - and that is a base of empirical knowledge people like me want to tap into. What have you learned about recordings, equipment, setup, room treatments, etc? Were my variable experiences due to variables in the implementation? That's what I want to learn from.

At the same time, I'm aware that a lot of audio reproduction is not yet a science. In my profession, we often don't have the knowledge or time to understand the behavior of a particular system in detail, so we run intuitively guided experiments to figure it out and try to solve a problem quickly, even if we don't have a deep understanding of what's going on in the system. That's called "hacking" in the software world.

Reading the literature about audio reproduction, there are some things we have pretty well documented about the "black box" ear/brain system and its interaction with reproduction technology. The primacy of frequency response in loudspeakers, the subjective preferences of listeners in performance spaces, the basic strengths and weaknesses of stereo, etc. But there are also areas where we are just still hacking to a certain extent. How many channels, placed where, in what kind of listening environment, are necessary to recreate a near perfect illusion of reality? What are the factors preventing binaural from realizing its theoretical perfection? To name just the subjects of this thread.

Presuming we find answers to those questions for some listeners, will those answers be universal or listener-specific? We just don't have the body of controlled experiments to prove these things one way or another - not even close - so we're reduced to either trusting what we know and making that work as ideally as possible, or hacking to see if there's something better - and then trying to synthesize that bottom-up knowledge into a more foundational theory. In many ways, I'm just more of a hacker :)

Scott
Scott, well said.

Just to be clear on my own preferences, given that I have discovered and been able to amass a satisfying large library of discrete Mch recordings, I strongly prefer those over any attempts to synthesize Mch or envelopment from 2.0. I have experimented with synthesis, and, while it is not bad, it just does not get to the level of discrete Mch recordings. I also do not feel any need to further enhance via synthesis of more channels beyond what discrete Mch provides. It is also fair to say that I would not have committed to Mch at all if only to synthetically expand 2.0. Although, I do find that a Mch system optimally configured for discretely recorded music also serves very well and satisfyingly for video in Mch sound as well.

It happens that by far the largest source of discrete Mch music is, for now, SACD. And, most of those releases in Mch were made in the last 15 years or so, using very advanced recording techniques and equipment. So, many of those are of very high audio quality compared to older recordings.

But, I am not locked into SACD or DSD. If some better medium comes along for discrete Mch offering sufficient music, I will gladly adopt it, even adding more speaker channels if warranted. And, in fact, I play my SACD rips from my NAS and PC with conversion to 176k PCM for the application of DSP speaker distance correction, bass management and Dirac room EQ. So, I am not stuck on DSD either.

So, discrete Mch is the best of the best, IMO. To me, that should be the priority in setting up and configuring a Mch system for music. I still remain curious as to why that apparently did not work out for you.
 
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#50
Aah, thank you, Scott. The reason I asked is because I do the same thing (Linkwitz LX521.4) - but with XO/EQ done in JRiver below 600hz vs XO/EQ/correction full range using Acourate. And I find myself switching from one to the other because they both have strengths and weaknesses (subjectively) with Acourate being far superior from a measurement perspective. I would like to choose one or the other and stick with it, but haven't been able to do that yet. Maybe just time to stop the critical listening and enjoy the music as I'm sure if I didn't have a choice I could live with either one. :)
 

Fitzcaraldo215

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#51
Scott, given your interest in electrostats, I should also have mentioned that my system uses 7 Martin Logan 'stat hybrids plus a single JL Audio f113 sub. They are of various sizes, and the center is an ML Stage horizontal 'stat hybrid mounted above my hi def TV monitor. The speakers, including surrounds are all mounted frontally facing the sweet spot. There are no special absorbing treatments behind the speakers.

For 5.0/.1 music, I play them in 5.1. The 2 back channels are only used on 7.1 source material from BD.

That has been my speaker setup for over 10 years. Obviously, I have been happy with it.
 

Fitzcaraldo215

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#52
Since this discussion, I have been thinking some more about the differences between discretely record Mch sound and simulated Mch derived from stereo or as additional derived channels for Mch. My perspective is from the viewpoint of live concerts in the hall, the acid test of Mch in my opinion. It is not about repanned studio mixes for surround sound, which can be great fun, but which are pretty simple and straightforward uses of Mch.

I think one major difference has to do with exactly what is contained in the signal in the surround channels. In discretely recorded Mch, the more distant hall mikes capture a combination of both direct sound from the stage from that perspective plus hall reflections from that more distant perspective. And, indeed what I hear from my surround channels sounds very much like a more distant replica of the direct sound from the front plus an added ambiance of the hall due to reflections. On playback, this mixed direct + reflected sound field from the surrounds combines with the direct frontal sound in complex ways, modifying the spatial perception via front/back phantom imaging and, to a degree, the tonality. Noticeably, it provides an enhanced frontal soundstage by pulling the image forward into the room somewhat, adding greater apparent depth, as well as widening the apparent soundstage by including side reflections. Meanwhile, the Haas effect keeps the perception of the performers precisely localized up front in space, where they should be.

Note that the surround channels do not just consist of "de correlated" reflections (not sure if I like the term or even know exactly what it means in this context), which add envelopment, although they also, of course, do contain that in discrete. I do not know to what extent various Mch synthesis schemes attempt to recreate both direct+enveloping reflected sounds accurately from the surrounds. I do know that I find them considerably less successful than discrete Mch.

I think synthesis tends to emphasize the envelopment, but it does tend not to provide the added image depth and "pull out" into the room toward the listener, a quality of Mch I greatly admire, myself. The role of the center channel is also important here. A discrete center mike will not exactly capture just a simple sum of L+R mike channels from its perspective, though I suspect many synthesis schemes do a simple L+R center.

I also think synthesis often tends to be somewhat monotonous in its perspective and not adaptable to recorded venues of different sizes and acoustics. Although, there were some early, junky algorithms allowing for manual selection - cathedral, symphony hall, jazz club, etc. - as pioneered by Yamaha, I think, in old AVRs. Some of those are still around in consumer grade HT gear, but generally not in hi end Mch prepros. There are other common, more advanced schemes from Dolby, DTS, etc. My older prepro had seeming dozens of varied synthesis algorithms, most unappealing. I did tend to prefer DTS Neo6 for a time for classical music, as did friends.

Synthesis was fun to play with for awhile, but the novelty has worn off for me. As I said earlier, its appeal for me has been overwhelmed by aggressively increasing the size of my discrete Mch library, now extending to thousands of albums.
 
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