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Anyone else using Multi-channel stereo instead of stereo?

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By the way, there are 3-channel recordings in existence--quite a few of them, in fact.  RCA Victor and Mercury in the early 1960s apparently recorded all of their classical performances using three microphones and three-channel tape recorders (of high quality for the time).  Those recordings were resurrected and cleaned up, then released on multichannel SACDs as "Living Stereo" and "Living Presence" recordings, respectively.  Now those are interesting to listen to, and you're usually never aware that you're listening to three channels instead of stereo--it just sounds better.

 

https://www.arkivmusic.com/classical/RCALivingStereo.jsp

 

https://store.acousticsounds.com/s/493/Analogue_Productions_RCA_Living_Stereo_LPs__SACDs

 

http://www.classicalcdreview.com/rcasacd.html

 

https://www.stereophile.com/news/081604mercury/index.html

 

R-3658790-1590610030-7628.jpeg.jpg

 

 

 

Chris

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51 minutes ago, Chris A said:

In the example that I posted above, it's clear that what's being done by different pieces of gear is not equivalent, although they're advertised as being equivalent. I hear those differences, and I don't usually like the synthesized implementations of 2-->5 channel that AVPs/AVRs use.  Finding out what they're actually doing is usually a lot more difficult than just listening to the results and judging for yourself if it is better or worse. 

 

I think the reason why some of the folks on this forum still use PWK's method, and not because it's necessarily superior, but because it's a user-controllable and known process, even though it may significantly narrow the apparent stereo soundstage.  If you set the loudspeakers along the long wall of an oblong/rectangular room, then the loss in apparent soundstage width isn't noticed as much.  I think PWK knew what he was doing in 1959 when he published the article on 3 channels from 2 channel channel sources.  He had also apparently experienced using the Bell Labs setup that was pioneered perhaps 15-20 year earlier, and he understood the pros/cons of what he was proposing.  I'm not sure about the synthesized modes that we get today in our AVPs/AVRs. 

 

Nowadays, you get the algorithms in canned fashion with bells and whistles that you didn't ask for put in, ostensibly because someone in marketing though it sounded "better than the competition" (probably using questionable recordings in the first place to make their judgments). 

 

JRiver seems to have a better handle on things in terms of the signal processing for psychoacoustical effects, but I can't say that I have first-hand experience listening to what they've done, and I certainly don't know what they've actually implemented.

 

Caveat emptor applies..."let the buyer beware".

 

Chris

I will certainly compare my Yamaha-generated center channel to the PWK method some day. I’ll need a center channel amp and some free time. I bought the KP-250 because it was cheap and had nearly the same design as my two Heresy speakers basically to try as a center. I'd like to hear the PWK method for historical purposes, even if I eventually decide the modern algorithms are better. I'd actually love to hear all the algorithms mentioned in the papers as well as the PWK method. Not as a blind test, I'd like to hear them and compare out of curiosity. 

Edited by Pondoro

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21 minutes ago, Chris A said:

In the example that I posted above, it's clear that what's being done by different pieces of gear is not equivalent, although they're advertised as being equivalent. I hear those differences, and I don't usually like the synthesized implementations of 2-->5 channel that AVPs/AVRs use.  Finding out what they're actually doing is usually a lot more difficult than just listening to the results and judging for yourself if it is better or worse. 

 

I think the reason why some of the folks on this forum still use PWK's method, and not because it's necessarily superior, but because it's a user-controllable and known process, even though it may significantly narrow the apparent stereo soundstage.  If you set the loudspeakers along the long wall of an oblong/rectangular room, then the loss in apparent soundstage width isn't noticed as much.  I think PWK knew what he was doing in 1959 when he published the article on 3 channels from 2 channel channel sources.  He had also apparently experienced using the Bell Labs setup that was pioneered perhaps 15-20 year earlier, and he understood the pros/cons of what he was proposing.  I'm not sure about the synthesized modes that we get today in our AVPs/AVRs. 

 

Nowadays, you get the algorithms in canned fashion with bells and whistles that you didn't ask for put in, ostensibly because someone in marketing though it sounded "better than the competition" (probably using questionable recordings in the first place to make their judgments). 

 

JRiver seems to have a better handle on things in terms of the signal processing for psychoacoustical effects, but I can't say that I have first-hand experience listening to what they've done, and I certainly don't know what they've actually implemented.

 

Caveat emptor applies..."let the buyer beware".

 

Chris

 

In your example I find it odd that a low-pass filter would be applied to the center and surrounds.  Wouldn't they more likely get a high-pass because they might not be very capable down low?

I agree I tend to prefer a "user-controllable and known process".  To that end I may try some 2 to 5 channel configurations in my Xilica 4080 MiniDSP setup since I could have at least rudimentary if static control over channel routing/mixing, level, phase, delay, and high-pass/low-pass. 

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24 minutes ago, Delicious2 said:

Wouldn't they more likely get a high-pass because they might not be very capable down low?

Remember my comment about "how humans hear".  It's about what the psychoacoustic requirements are, not typical surround loudspeaker capabilities, which are often not designed to support the psychoacoustics requirements. 

 

The surround channels are usually "echo channels" that are attenuated in high frequency content because of frequency-dependent air absorption & diffraction, and interior venue surfaces that are more effective at absorbing and scattering HFs than LFs.   So the echos are always low-passed.  That's what you're trying to recreate.

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1 hour ago, Chris A said:

Remember my comment about "how humans hear".  It's about what the psychoacoustic requirements are, not typical surround loudspeaker capabilities, which are often not designed to support the psychoacoustics requirements. 

 

The surround channels are usually "echo channels" that are attenuated in high frequency content because of frequency-dependent air absorption & diffraction, and interior venue surfaces that are more effective at absorbing and scattering HFs than LFs.   So the echos are always low-passed.  That's what you're trying to recreate.

So surround channels could be four to ten inch full range single speakers, and save a lot of money.

 

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1 minute ago, Pondoro said:

So surround channels could be four to ten inch full range single speakers, and save a lot of money.

 

Or just use a reverb.

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As long as their frequency response reaches down to ~30 Hz or below with clean, distortion-free bass, I guess you could use "full range" drivers.  I'd think that the modulation distortion would begin to eat you up at any useful SPL, however...I'd rather have a bit more clean SPL capabilities. 

 

Chris

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5 minutes ago, billybob said:

Or just use a reverb.

Actually, this is where the psychoacoustics kick in:

 

The surround loudspeakers need to be physically separated so that they are providing direction of direct arrivals at least 20-30 degrees wider (outside) the direction of travel than their corresponding front channel loudspeakers. 

 

This is where Toole's book really helps to understand the psychoacoustic requirements.

 

Chris

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14 minutes ago, Chris A said:

As long as their frequency response reaches down to ~30 Hz or below with clean, distortion-free bass, I guess you could use "full range" drivers.  I'd think that the modulation distortion would begin to eat you up at any useful SPL, however...I'd rather have a bit more clean SPL capabilities. 

 

Chris

I didn’t realize such low frequency info was important to surrounds. For home theater I should have known, I have been near controlled explosions, the rumble coming back from surrounding hills differentiates the truly large explosions from small ones. All explosions overwhelm the senses, even with good hearing protection, at the moment of the blast. It is the thump in your chest and the echoes that tell you, “That one was big!” 

Edited by Pondoro

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17 minutes ago, Pondoro said:

I didn’t realize such low frequency info was important to surrounds. For home theater I should have known, I have been near controlled explosions, the rumble coming back from surrounding hills differentiates the truly large explosions from small ones. All explosions overwhelm the senses, even with good hearing protection, at the moment of the blast. It is the echoes that tell you, “That one was big!”

Yes, but most surround channels are typically only given lip service in practice, even in commercial cinemas.  But you've got it right.  The lower their response, the more effective they actually become to add to the sense of envelopment. 

 

One of the better figures from Toole's book shows you the effect of placement of the surrounds.  Note that one of the most effective surround channel arrangements actually put the surround loudspeakers forward of the listeners, not aft (ref. configuration "(b)"):

 

Figure 15-5.GIF

 

Here's another figure from Toole's book that also shows you the sweet-spot zones of where to place the surrounds:

 

Spatial Effect Balloon.GIF

 

If you've got a full 5.1 setup, try moving them forward sometime--I think you will be surprised with the results, subjectively.

 

My listening room is ~40 feet long (12 m), so you can hear the very low frequency reflections from the bass bins and subwoofers sweep back and forth over you when playing something that has very low frequencies (below 25 Hz).  J.S. Bach and Widor organ compositions in multichannel format fit the bill almost perfectly.  It adds so much to the sense of presence that it can elicit a "you are there" feeling as if sitting in the performance hall.

 

Chris

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1 hour ago, Chris A said:

One of the better figures from Toole's book shows you the effect of placement of the surrounds.  Note that one of the most effective surround channel arrangements actually put the surround loudspeakers forward of the listeners, not aft (ref. configuration "(b)"):

 

FourFront uses configuration (b), all fullrange, quite effectively. It is what I have in my living room right now, plus an optional center channel.

 

I have tried configuration (c), but I did not like the "shooting sound directly into your ears" aspect of the 90° speaker placement.

 

My favorite configurations are (d) and (i), if you have the space. I currently don't.

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21 hours ago, Chris A said:

This is the part that I think you need to take note of with PWK's approach (which was as complicated as he could withstand in ca. 1959 when he proposed a three-channel summing resistor network to create one of the first consumer-grade three-channel setups using Klipschorns and a center Heresy...at that time).

At 21 years old,  I built PWK's resistor box, but put a 20K potentiometer in the center circuit to give me variable center attentuation, on my DIY 3 channel speaker system (Big Bass Reflex Altecs R+L, with Center BR which would later be called a CornScala).

 

The center was adjusted by listening to Al Dimeola and Paco DiLucia's Mediterranean Sundance until the two guitars sounded a little closer to each other than was presented in the "ping pong" recording presented by the flanks alone, which were 14 feet apart. So when they sounded about 10 feet apart, the output of the center was about 4 db down from the R & L channel.

 

At 23, I bought my first pair of Khorns (Baltic Birch is all I could afford in the mid-70's) after getting my first bank loan of $1,000, having put down the initial cash down payment to order them from my local Klipsch dealer. Not long afterwards, I replaced my center speaker with a LaScala. I sold my 200 Watt/ch. Dynaco Amp and replaced it with a 75 W/ch. Dynaco after building some Peak Level Meters to reveal that Khorns only needed 10 Watts PEAK for cranking pop, rock, or fusion jazz music.

 

I had this PWK 2PH3 setup for 30 years and even heard PWK's own setup in 1985 at his home. His live recordings were the best I ever heard, and he was happy to know that I had the 3 channel setup at home.

 

The new millennium, got me interested in surround sound and I evolved over 20 years from 3 channels to 5, 6, 7, 11 channels! I still like to switch from 2 channel to 11 channels with the same subwoofers, depending on the source. Since I use the same system for movies and music, I like the way the Yamaha allows for both with more ways to simulate different concert halls that I can ever use or like in a single day of listening!

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17 hours ago, Chris A said:

As long as their frequency response reaches down to ~30 Hz or below with clean, distortion-free bass, I guess you could use "full range" drivers.  I'd think that the modulation distortion would begin to eat you up at any useful SPL, however...I'd rather have a bit more clean SPL capabilities. 

 

Chris

I agree 100% about this. Since the proliferation of powerful sub drivers came after PWK passed on, it's the very best way to get lower IM distortion from the mains. Paul was right about horn loading everything and horn loaded subs produce even less IM distortion and cleaner sub bass than any direct radiator which is also full of Harmonic Distortion when moving all the air required for high output below 40 Hz.

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23 hours ago, Pondoro said:

As Quad died in the 1970's "Time Delay" units were briefly popular. You had two channel stereo in front and variable delay in the rear two speakers. Some loved it, said it was "Quad without the format war incompatibilities", purists called it "distortion." 

When I heard the demo at a Stereo Show in Detroit with a live recording on LP, I was impressed when I heard applause all around me (this really blew my mind), so I made the investment. The problem with the "bucket brigade" rear channels system (which made mine a 3 fronts + 2 rears at the time) was it was extremely dependent on the recordings, and did not work well for all music, so I quickly got rid of it after about a month of dissapointments.

 

Moral of the story. Demos are always done to impress, but long term ownership can easily disappoint after the "cool factor" wears off. Modern signal processing in AVR's and Pre-Pros do a much better job at presenting the grand ILLUSION, which is all this crap is anyhow. It all sucks compared to live acoustic instruments.

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23 hours ago, Chris A said:

Yes, but most surround channels are typically only given lip service in practice, even in commercial cinemas.  But you've got it right.  The lower their response, the more effective they actually become to add to the sense of envelopment. 

 

One of the better figures from Toole's book shows you the effect of placement of the surrounds.  Note that one of the most effective surround channel arrangements actually put the surround loudspeakers forward of the listeners, not aft (ref. configuration "(b)"):

 

Figure 15-5.GIF

 

<SNIP>

 

Chris

I've been staring at this for a day or so now. It appears to me that b, c, d, e and i are basically "equal." Not "the same" but to their audience they were equally good. I sure wish they had included 3 speakers across the front - Left - Center - Right. Option i is the same as d, scores a tiny bit worse (again I would say, "The same") but requires an extra speaker and amp. I bought a third speaker exactly to try the PWK method. As I said I will run it with whatever algorithm Yamaha has built into my receiver as well. But this study, which did not ever try simply adding a center, seems to show that a center did nothing, at best, when added to  configuration d.

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16 minutes ago, Pondoro said:

But this study, which did not ever try simply adding a center, seems to show that a center did nothing, at best, when added to  configuration d.

 

I have found that to be largely true when seated dead-center. Off-center, the story changes in favor of the center channel.

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3 hours ago, Pondoro said:

I sure wish they had included 3 speakers across the front - Left - Center - Right.

I think if you look in the book at the next figure (15.7 in the third edition), you will see the data on different configurations, including with and without center channel.

 

If you think about it, why would any configuration sound worse when a center channel is properly dialed in and has the right directivity?  Subjective perceptions probably shouldn't degrade if all factors were fully under control. My experience is that the researchers themselves sometimes have uncontrolled factors in their setups (such as using direct radiating loudspeakers that have polar control issues, etc.), so small differences in the performance of the configurations shown in the figure above are probably not significant, but the larger changes seen in configurations a, f, g, and h are probably significant, perhaps very significant.  The other configurations will be much closer together in performance (the subjective quantity referred to as "LEV" or listener envelopment).

 

Chris

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1 hour ago, Chris A said:

I think if you look in the book at the next figure (15.7 in the third edition), you will see the data on different configurations, including with and without center channel.

 

If you think about it, why would any configuration sound worse when a center channel is properly dialed in and has the right directivity?  Subjective perceptions probably shouldn't degrade if all factors were fully under control. My experience is that the researchers themselves sometimes have uncontrolled factors in their setups (such as using direct radiating loudspeakers that have polar control issues, etc.), so small differences in the performance of the configurations shown in the figure above are probably not significant, but the larger changes seen in configurations a, f, g, and h are probably significant, perhaps very significant.  The other configurations will be much closer together in performance (the subjective quantity referred to as "LEV" or listener envelopment).

 

Chris

I absolutely agree - b, c, d, e and i are "identical." For that matter a, f, g and h are identical (to each other). You can read a graph too finely. And the psychology industry is in the midst of the "replication crisis", in which famous and groundbreaking experiments cannot be repeated with the same results. Still this is fun, and the study here is informative.

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On 12/11/2020 at 1:53 PM, Pondoro said:

But this study, which did not ever try simply adding a center, seems to show that a center did nothing, at best, when added to  configuration d.

That's because the original Stereo Broadcast (Bell Labs) from 1933, of a live Orchestra, conducted by the great Leopold Stokowski use 3 speakers that were spaced about 40 ft. apart. with a center channel. Also they had a full 3 discrete channel broadcast from 3 separate microphones from that live Symphony Orchestra. Different is not the same. The 2ph3 (with a mono marriage of R+L in the middle was a reasonable compromise that worked almost as well as the discrete implementation of 3 channels of the original STEREO broadcast by wire from one city to another. I read the Klipsch papers when I was 19 years old. BTW, PWK only listened to reel to reel tapes of Symphonies he himself recorded with only 2 spaced omni microphones. The ONLY LP that he owned, is the original "white album" (with Stokowski's autograph) made popular by the Beatles 3 decades later, was of the broadcast outlined in the next paragraph:

 

A concert of the Philadelphia Orchestra at the Academy of Music, sponsored by AT&T was captured by three microphones spaced across the front of the orchestra and transmitted via three long lines to Constitution Hall in Washington, D.C. where three amplified loudspeakers reproduced the orchestra sound.  The orchestra was conducted by Alexander Smallens, assistant conductor of the Philadelphia Orchestra, with Stokowski controlling sound balance. 

 

PWK's own developments were done in a room that allowed 25 foot spacing between Klipshorns. That room became the Klipsch museum PWK showed me in 1985 (it was across the street from the Plant in Hope, I have pictures) and used Dr. C.P. Boners diffusion panels to make better sound reproduction.

 

The problem wit "D" is that in all configurations the speakers are extremely close together, making the center channel unnecessary for 2 channel music nowadays because the spacing is too narrow and the Center channel is, primarily, for Movie Dialog. So it's an apples and oranges comparison at best.  

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