[Daygloworange]

I though it would be interesting to start a thread based on 360 deg. sound reproduction. There seem to be a number of different (new)techniques out there. I myself played around many years ago with Quadraphonic (Q4) style recordings many years ago.

I thought it would be interesting to find out what hardware/software systems other members have been exposed to (either in their own systems, or others) so that we can have them all listed here (in one thread) for others who are interested in learning more about what the current (and emerging) technologies are, and the science of sound.

Cheers

[Mag]

We used to have a quad receiver (brand; I think was Reflex) when I was a teenager. Not sure what happened to it? Might have been sold at a garage sale, I'll ask my brother.
Anyway we used Quad headphones with it,which I think we still have, might need repairs. I liked the quad sound and thought it was quit good. However around that time my friend got a Realistic stereo and I learned that good stereo beats quad. Also my first stereo out of high school, I bought Stax headphones which bettered quad, but were really harsh on the highs.
But quad got me started on 360 degree sound and I preferred it over stereo. I guess I've never heard good stereo imaging with just 2 speakers.
But as mentioned in another thread I switched to multi-channel stereo with ten speakers to create a 180 degree soundfield. Which blows away any surround or conventional stereo I've heard. And the few people who have heard it say "It's the best they've heard."
However my experience in 2 channel stereo is limited. And it's quite possible that somebody out there with killer speakers and a good room is achieving better stereo sound with two speakers than I am with ten.

[tschanrm]

Here's part one of my two part post in discussing new sound widening or spatializing technologies.

The below systems I've experimented claim a sound space beyond 60 degrees. All notes done with 2-channel audio, and multichannel movie soundtracks. Test room is a small rectangular-shaped room, approx 14ft wide by 12 ft long, 10ft ceiling, furniture, no sound absorbing treatments.

Q-Sound Spatializer
Works well at expanding the frequencies to the left/right of the speakers, but only within a limited frequency band. No sense of extra spatial resolution, if anything its less and feels like a 2D planar wall of sound in front. This system is not effective outside the sweet spot and is good for a single listener.

Dolby Virtual Speaker
When set to 'Reference Mode' it doesn't sound much different than stereo. However, when set to 'Wide 2', there is a sense of wideness, with certain sounds extending beyond 60 degrees, both horizontally and vertically, but I'd say no more than about 100 degrees. As it was designed for movies the wide explosions and gun shots seems real, but when listening to music it alters the frequency range to a point where some instruments sound distinctly unnatural. This system is not effective outside the sweet spot and is good for a single listener.

TruSurround XT
Similar to Dolby Virtual Speaker's 'Reference Mode', but with an obvious eq boost in the bass region. Overall not very effective in or out of the sweet spot.

Ambiophonics
This is for the 2 Speaker 20 degree arrangement using AudioMulch and the RACE version for this system. For music it is very enveloping, creating a wide soundstage about equal to that of Dolby Virtual Speaker but without the unnaturalness. Certain Left/Right sounds tend to mush around the the 10-30 degree center, while other sounds extend way out to 120 degrees or so. Some sounds extend vertically high, feeling about a foot or two below the ceiling. For movies it is not so good. Ambiophonics crosstalk cancellation/HRTF method molds the  frequency response so there is a large hole in the vocal region, making movie dialog sounding hollow or muted compared to a discrete multichannel system. This system is not effective outside the sweet spot and is good for a single listener.

Stereo Dipole
Only have heard demo files, but sounds similar to Ambiophonics. This makes sense, as the arrangement is a low speaker separation (10 degrees). This system is not effective outside the sweet spot and is good for a single listener.

Mirage Omnipolar
Not a special type of software or hardware per say, but rather a new speaker arrangement. This was a test with the Mirage Omni 260. They were in my main system for about 6 months before selling them. It backs up the marketing hype and reflects sound around the front of the room, but not with a well-focused center image. Closest comparison is the Qsound in that it was this wide wall of sound, but unlike Qsound it didn't have phase issues, did sound very close to standard stereo and was more spatial (felt more 3D instead of a 2D wall of sound). Works well with music and movies, and is suitable for more than one listener.

Polk SDA SurroundBar
This was at my parents house. They have a large open-style living room, rough size estimate is 30 ft. wide by 60ft long or so, angled ceilings starting at 8ft and elevating to 15-20ft or so. This was the Polk SurroundBar, one of the more recent SDA products. Overall, the speakers sounded pretty good, but I never once heard anything extending beyond the speaker itself. I tried it with multichannel movies, and also in 5 channel stereo mode with the center channel disabled. Could be the room, but I spent many hours trying to tweak the sound and never heard anything but standard stereo from the SurroundBar.

Comparing all these sound technologies, I would only recommend Mirage's Omnipolar technology as a substitute for the standard stereo configuration. My emphasis on substitution, not replacement, comes from the fact that for a single-listener experience stereo provides a more precise soundstage. Omnipolar technology is great when you want a stereo setup for multiple listeners - I also think Omnipolar would do great as a 5.1 discrete movie setup.

Stay tuned for part two of this post when I discuss my journey with OPSODIS technology...

[tschanrm]

Here's part two fo the two part post on new sound widening or spatializing technologies.


OPSODIS
This is not a true OPSODIS system I setup, but it's the closest I could create. No passive crossovers, all done digitally with FIR implentation, 600 Hz low, 600-4000 Hz mid, 4000+ Hz high. HRTF and phase processing done through AudioMulch with Waves Panorama 5.1 demo VST plugin. I've done two setups with this system:

 Setup 1. Speakers split at around 6 degrees (highs), 32 degrees (mids), and 180 degrees (woofers).
Setup 2. Speakers split at around 6 degrees (highs), 32 degrees (mids), and about 90 degrees (woofers).

I've found OSPODIS requires a *very* precise setup in regard to horizontal and vertical speaker distances for the mids and highs. Being just a half-inch off can have a dramatic impact on sound quality, shifting the soundstage.

In both setups, regardless of HRTF or phase modeling, you get a sense of 180 degree soundfield (I would say over 120 degrees with setup 2). This image from ISVR visualizes the sound:

http://www.isvr.soton.ac.uk/FDAG/VAP/images/osd_prin.jpg

OPSODIS is unlike any other loudspeaker setup I've tested, and it's the setup I've spent the most time with (over 1 year of tweaking).  Here's my rundown of the system:

When both the left and right speakers are kept in phase, it sounds somewhat similar to stereo. The in-phase system has upper-mids and highs that stay within the 30 degree boundary across the horizontal plane, but do extend vertically upward. Mid and low frequencies can extend anywhere from the center to 180 degrees both horizontally and vertically. Reverb effects in some songs are eerily in focus, and actually is detrimental as it makes some music sound overly-processed (or these songs could just be overly processed).  When sitting out of the sweet spot, you tend to hear whichever speaker you are closest to, but this is less noteable in setup 2. Plus, when sitting out of the sweet spot, there is a loss in bass depending on where you move. Highs and upper mids are localizable to the speakers.

OPSODIS is interesting in that you can have some cross-talk cancellation by simply keeping the L/R channels out of phase (discussed in the patent: http://www.freepatentsonline.com/6950524.html). I believe the effectiveness of this crosstalk method depends on the crossover, so I maxed out the FIR implementation to the point where I could almost hear ringing artifacts. When the Left and Right channels are 180 degrees out of phase, setup 1 becomes out of the question for any real application. When you're sitting perfectly in the sweet spot it sounds better than the in-phase system. However, move just an inch and you're ears are bombarded with bass phase pressure.

With setup 2 L/R out of phase, highs still stay within the 30 degree horizontal plane, but become much less localized to the speaker. Overall, there is a widened image when compared to the in-phase setup. Left and right mid-bass notes stay left/right vs. the in-phase system. What's more interesting is that when you sit outside of the sweet spot, the image still stays in the center and your ears don't focus on the closest speaker like with the in-phase system. Plus, bass is much more consistent as you move outside the sweet spot. However, the out of phase part can mess with the overall sound and it's not always desirable.

Some notes on HRTF via Panorama 5.1. It uses direct, reflecting, and reverberation sound to try and simulate an environment. Overall, it can add ambience to the signal and help emphasize the spatial aspect. With most of the predefined settings, it makes you feel like you are in a far back venue seat, not up close, but it is a convincing effect. It's a bit of a burden using it because some recordings sound good after tweaking the settings, with other songs no amount of processing makes the HRTFs sound "right" with the song.

Conclusion
All-in-all, OPSODIS proved to be the most effective and convincing sound setup out of the whole group. It can provide fairly convincing ambience and realism to some music (depends on the recording style I guess) when using HRTF, and a unique listening experience. Plus, it's semi-suitable for multi-listener experience - sound always comes from the center but feels a little flat and 2D compared to the single sweet spot.

For music the FIR crossover implementation is fine, but movies you need an IIR crossover (reduced sound quality) to keep the sound in-sync with the image. Here's the problem with movies though - you need a TV right where the tweeters should be (eye level). With the whole system needing to stay on the horizontal plane, you need to either elevate the whole system below the listener (which doesn't sound good), or above the TV (which is near impossible with the outside woofers). If OPSODIS wasn't such a pain to get right for all material, and was easy to setup with a TV, I would be using it now. Even after a year it's still just a basement project, just a very good sounding one. However, I may consider buying a commercial OPSODIS solution, now that Marantz finally realeased their ES7001 to the US.

Hope you found these posts informative and realize that so far I've not heard a system that demonstrates 360 degrees of acoustic bliss.

[stereocilia]

Hafler Surround from two channels:
If you've got two extra speakers and some extra wire it can be fun to connect them using the matrix arrangement where you drive the rear speakers with the difference between the left and right positive terminals.  I think I said that right.   

R-Space:
This may be a bit off topic, but here's one that's being used for hearing aid research at Etymotic:
http://www.hearingreview.com/issues/articles/2007-10_06.asp

[dwk]

tschanrm, I'm slightly confused by your OPSODIS descriptions when you talk about in-phase vs out-of-phase and some degree of XTC.  Did your setup implement explicit cross-talk cancellation, or did you simply use FIR filters for xovers and spread the drivers? If you did use explicit xtc, then I guess I'm confused by your experiments with in/out of phase arrangements.

I'm very interested in the the OPSODIS approach based on my relatively brief experiments with the Ambiophonic software (both the audiomulch chain and the Choueiri filters provided with jace), although my main speakers aren't particularly well suited to it.

[TheChairGuy]

The Walsh driver, long championed by Ohm Acoustics and the radial driver from Decware would certainly quality.....if only in midrange and low frequencies, as omni-directional/360 degree.

Conversely, the high frequency units from Linaeum and, more recently, the similar functioning CDT high frequency units from Gallo Acoustics are 360 degree (or close)

[Duke]

Focusing on stereo loudspeakers rather than multichannel and/or signal processing, in my opinion a 360 degree radiation pattern is too wide and often produces exaggerated central image size.  I have adopted a 90-degree bipolar pattern for my top-of-the-line offering, with the drivers toed inward at a 45 degree angle and positioned a good 5 feet or so out from the wall behind the speakers.  Imho this approach gives more realistic image size than omnis along with a good sense of envelopment.

I guess that would really be 90 + 90 = 180 degrees, rather than 360 degrees; but the intention is to compete against omnis and semi-omnis (like the big Shahinians).

Duke

[dorokusai]

tschanrm - Just to comment on your Polk Surround Bar testing....

SDA, Stereo Dimensional Array was not designed, originally, as a 360 source of sound reproduction. That was much much later.

The SBar isn't dependent on the sidewalls for the surround effect, like the Yamaha, but that's a pretty wide room for that loudspeaker. I don't think you had to spend hours trying to tweak it but thanks for taking the time to do so The SDA surround channels definitely work but in the testing I've done with them, I had to run the rear channels +3-5db to get the surround to kick out a bit. The best demos for me were ones that really go out of their way to give the surround channels a workout. Otherwise, I agree, it's hard to get a feel for it. Does it replace a bonafide HT? No, that's silly.

There are two more versions on the market now, one of which includes DSP room optimization. I wish they had come out with either one of these models first, but I'm just an internet dude. You can check them out on the website if you're at all interested. I don't know where you're located but if your a Marylander, you're more than welcome to come on over for a demo.....I can promise you'll leave with a full stomach and at least some good music to look into

Mark

[hifitommy]

such as the MBLs and the ohm acoustics employing the walsh driver.  true omni radiation requires GOBS of power as the sound isnt only directed at the listener.  that said, the MBL101s would be on my short list had i the money.

the 101s are $50k but they do make a smaller unit for $10k (i dont have THAT kind of money either).  ohm does still market some affordable speakers.

surrounding yourself with a dyna quadaptor is a valid method, i use it on all sources all the time. 

magneplanar mmg speakers are only $550 and coupled with a sub can be a tremendous main sound system.  at present, thats what i am listening to with dynaquad as surround.  even without the dynaquad, the sound is quite spacious.

[Housteau]

a sound space beyond 60 degrees

I don't think this is too much to ask for within a properly set-up 2 channel system without any other special gear needed.  I am nowhere near a 360 degree presentation, but certainly well beyond 60 degrees.  Of course it is recording dependant, but I would say routinely I can get between a 100 to 120 degree soundstage.  Q recordings expand upon that higher number some.  Most traditional recordings tend to average around the lower one.

A long wall placement with adjustable dipoles in an equilateral triangle to the listening position allows this for me.

[tschanrm]

tschanrm, I'm slightly confused by your OPSODIS descriptions when you talk about in-phase vs out-of-phase and some degree of XTC.  Did your setup implement explicit cross-talk cancellation, or did you simply use FIR filters for xovers and spread the drivers? If you did use explicit xtc, then I guess I'm confused by your experiments with in/out of phase arrangements.

I'm very interested in the the OPSODIS approach based on my relatively brief experiments with the Ambiophonic software (both the audiomulch chain and the Choueiri filters provided with jace), although my main speakers aren't particularly well suited to it.

I've done both XTC and just L/R out of phase with each other. The odd thing is, for right or wrong, when I applied HRTF ambience effects, the simple L/R out of phase always sounded better. It could have been from my XTC implementation, which was a Panorama VST plugin for each channel pair, or just the fact that L/R out-of-phase is less processed. Keep in mind this setup has been a science experiment, and a real OPSODIS system I would hope would improve on the sound.
 
Another thing I should mention on OPSODIS: the most critical areas for sound reproduction are near the crossovers. The thesis doc on OPSODIS details why (I believe for crosstalk cancellation again), but the key thing I got out of it was close phase and db matching near the crossovers. I would have to reread the papers again to confirm this though.

If you don't add the ambience into the OPSODIS system, I see no real advantage of it over standard stereo. The whole idea behind it is to simulate another environment (or binaural synthesis). If you are expecting an enhanced stereo experience by simply breaking your speakers apart at different angles, you will be sorely dissapointed. The reason is that my stereo setup sounds wider than the speakers, however, when I try and simulate a room environment, the OPSODIS system always sounds more realistic. I've also found simulating live untreated rooms and large spaces to be more realistic sounding than a quiet or dead room.

By the way, binaural recordings on OPSODIS sound phenemonal. I have some sample binaural recordings, but two really stand out: A bus stop and an ocean sample. When you close your eyes listening to these, it really feels like you're there - the ocean one feels like your face is half-way in the water. I've had family members sit down in "the spot" and close their eyes, all they do is smile and laugh, they don't believe what they're hearing. It's the closest thing to headphone binaural reproduction I've heard.

If only regular recordings sounded anywhere near as real......thats the kicker. Those binaural recordings spoil you big time. Thats why the Marantz system has me so curious. If they can simulate just some of that binaural listening environment over to regular recordings, I'll purchase it in a heartbeat.

[tschanrm]

tschanrm - Just to comment on your Polk Surround Bar testing....

SDA, Stereo Dimensional Array was not designed, originally, as a 360 source of sound reproduction. That was much much later.

The SBar isn't dependent on the sidewalls for the surround effect, like the Yamaha, but that's a pretty wide room for that loudspeaker. I don't think you had to spend hours trying to tweak it but thanks for taking the time to do so The SDA surround channels definitely work but in the testing I've done with them, I had to run the rear channels +3-5db to get the surround to kick out a bit. The best demos for me were ones that really go out of their way to give the surround channels a workout. Otherwise, I agree, it's hard to get a feel for it. Does it replace a bonafide HT? No, that's silly.

There are two more versions on the market now, one of which includes DSP room optimization. I wish they had come out with either one of these models first, but I'm just an internet dude. You can check them out on the website if you're at all interested. I don't know where you're located but if your a Marylander, you're more than welcome to come on over for a demo.....I can promise you'll leave with a full stomach and at least some good music to look into

Mark

Thanks for the offer Mark, I'm in Wisconsin, so that's a bit of a trip. The only time I felt a sense of spaciousness from the SDA speakers with the SurroundBar was with test tones - YMMV I guess. And to be fair, I never upped the rear speakers to 6+. I'm not big into adding that much db increase in the digital domain because most current recordings are mastered so close to full-scale that those SDA speakers would recieve a clipped signal.