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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#41
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Sony SL-2700 Betamax
:We all know that you think you know
everything about eveyrthing, and you've bragged about being the best in your field." I do come off as a pompous ass huh. This best in the field, someone else said that. And it only applies to this state. Your field is not my field. I am also not what I once was. My ield actully narrowed, it was lucrative for a time, but no more. Yeah, twenty years ago I was the HNIC. I knew now to get sit done, the best, the fastest. The owners of the company did what I told them to do. If you really have to have proof, /I can arrainge a meeting. They would testify to this in court. Anyway, enough of this tweet ****. What about this dude's SL-2700 ? You WANT this to work, know why ? It is not SuperBeta, and has no RMS detector ?which means COPYGUARD DOES NOT WORK. It just records it. Now if you take that Beta tape and record it back to VHS, the copyguard is still there. It will **** up the copy just like the original did. But as the proud owner of the SL-2700 or some other nice Soy deck, HYOU can view the movie at any time. I won't be selling mine. (SL-HFR60 with the HFP100) |
#42
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Sony SL-2700 Betamax
"This is called DynaQuad. It was first officially proposed by David Hafler..
OFFICIALLY. The same thing has been caled everything. Quad this and quad that. From Alphaquad to Omegaquad lol. And when that $65 Dolby chip is in simple surround, it simply just nulls part of the L+R signal. It does work a bit better than a resistor though, if that's what you want. " |
#43
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Sony SL-2700 Betamax
William Sommerwerck wrote:
I hope the following doesn't sound unduly ad hominem. However, the differences are plain. The problem with you "beta was better" guys is you never admit that during the great vhs vs. beta wars, 99% of the people who bought them had crap televisions that probably couldn't produce 280 lines of resolution. I'd bet most tv's in the late 70's when home video started to gain ground still had some vacuum tubes. It was a coax hookup, not line outs. If there was a difference on paper, thats where the difference ended. The simple fact of the matter was, most people simply could not tell the difference from one to the other. People with trained eyes, possibly. There was no day and night difference between them, there couldn't of been because few people owned any kind of set to watch them on, to notice the difference. The only credit I give the beta format was when the copy protection **** came out (copyguard), what worked on vhs, didn't on beta. So if you needed to make an archival copy of something, doing it from beta worked better. I'm with the other guys, mechanically, beta machines were built like **** and didn't last long in normal use. Transport problems were difficult to repair and usually didn't last. Being they were usually more expensive than the vhs counterparts, they were just a poor value for the money. -bruce |
#44
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Sony SL-2700 Betamax
You do know that Ampex started the development of VHS before they
sold out to a consortium of japanese companies to raise much needed funds for their financial survival? Ampex wanted to make a cheap, scaled down version of their existing 1% 2" tape systems, to sell at an affordable price for consumers but ran into cash flow problems. That's new to me. I don't see why Japanese companies aren't capable of designing poor-quality products on their own. (RCA had been working on a consumer video recorder for years, but felt it wouldn't be marketable until it hit the same price point as color TV -- $500.) The Betamax machines I worked on treated the tape a lot worse than VHS. That's not altogether surprising. Beta pulled the tape into an elongated loop around the drum, to isolate its motion -- which is why Beta has less line jitter. Some had the tape sliding against itself to simplify the loading and unloading. I'm not sure I understand. Having seen both in use in a broadcast station, the cheap VHS was much better than any Beta, other than the overpriced ENG version that only got 20 minutes per tape. All Sony machines needed a TBC to meet FCC requirements, but I could feed a $79 VHS tape into our Vital Industries Squeezezoom and get a picture that was stable enough to broadcast. You are one of the most-knowledgeable people (about anything) I've ever met, but here I have to say "No way, José." VHS has serious time-base problems. I first noticed this the early 80s when I was scanning a late-night show I'd recorded * -- why was the picture visibly sharper than in normal play? I looked closely and saw the reason -- severe line jitter. When scanning, there was either less of it (for the same reason analog recorders have less flutter at higher speeds), or the eye did a better job of averaging the errors. Just as I judge audio equipment by what I hear, I judge video equipment by what I see. When VHS recordings have obvious time-base problems -- what am I supposed to conclude? * The machine was a high-end RCA-branded Panasonic. |
#45
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Sony SL-2700 Betamax
"Bruce Esquibel" wrote in message ...
William Sommerwerck wrote: I hope the following doesn't sound unduly ad hominem. However, the differences are plain. The problem with you "beta was better" guys is you never admit that during the great VHS vs. Beta wars, 99% of the people who bought them had crap televisions that probably couldn't produce 280 lines of resolution. I owned an NAD MR-20A at one time, and my SuperBeta HiFi machine made recordings that were //almost// indistinguishable from the broadcast. Obviously, if they were played on modern displays, the loss of quality would be more visible. The simple fact of the matter was, most people simply could not tell the difference from one to the other. People with trained eyes, possibly. You don't need trained eyes to see the difference. It isn't at all subtle. There was no day and night difference between them. There couldn't have been because few people owned any kind of set to watch them on, to notice the difference. You're kidding, of course. One of the most-noticeable problems with VHS is the lousy color. Not only are hues sometimes off, but the chrominance doesn't always fill the luminance! I can't speak for or against the quality of Beta transports. They were more-complex than VHS, so, in principle, they should have been less reliable. I never had trouble with my SL-HF900 deck. It still works. |
#46
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Sony SL-2700 Betamax
On Wed, 29 May 2013 18:53:34 -0400, Smarty wrote:
On 5/29/2013 12:59 PM, Jeff Liebermann wrote: On Wed, 29 May 2013 15:28:34 +0000 (UTC), Cydrome Leader wrote: If fuses blew on the amp, I'd not be in a hurry to start replacing them. I'd probably disable channels in the surround decoder. Chuckle. I have an old Heathkit AA-2010 quad channel amplifier. http://www.audioasylumtrader.com/ca/ca.html?ca=23000 I'm down to one channel now, as the other three have blown up over the years. When the last channel dies, I'll probably fix it and start over. My ears are somewhat screwed up, so quad sound never did anything for me. In the early 1970's, I attened an AES (Audio Engineering Society) convention, where the hot topic was quadraphonic everything. I tried on quad earphones and heard nothing interesting. I listened to a serious discussion between "experts" over whether the listener wants concert hall realism, which meant sitting in front of the orchestra in stereo, or whether he wants to be "immersed" in the sound, which meant sitting in the middle of the orchestra in quad. Meanwhile, the movie theaters were having a bit of a problem with quad sound, which tended to produce dead spots. Subsequent to the original release of quad headphones, in the late 60s, considerable research was done on ear / brain localization and spatial imaging, funded in part by the Air Force / DARPA (to facilitate heads up display direction of arrival cues for pilots being fired upon from 360 degrees in azimuth). Some seminal work was done at the University of Darmstadt, Germany, the prior art upon which Bob Carver's original "sonic hologram' patent was granted. http://en.wikipedia.org/wiki/Bob_Carver The technical significance of the findings was the intra-aural spacing of the typical human and the resulting time difference of arrival from the earlier to the later ear, combined with the comb filter created by the external ear's ridge structure (pinnae) allowed the brain to build a mental map of where things arrived from acoustically. A given angle of arrival in azimuth and elevation at a given frequency would have a learned interpretation of where it arose from. This was in addition to the reverb decay times and spectra influencing / defining the enclosed space in which the audio was captured / simulated. The bottom line was that headset design could not inherently replicate the intra-aural delays and especially the comb filter results accurately for all individuals, since each of us has a unique set of parameters. Partially successful alternatives such as binaural recording and playback have overcome this to some extent but not fully. Thanks. That explains why I didn't hear anything resembling quadraphonic sound. My ears are bad, but not that bad. There were others in the group that claimed the quad headset was wonderful sounding but they would be fiddling with the controls, or moving the headset around trying to "improve" the experience. I also noticed a few puzzled looks as they were playing with the headset. I few shows later, someone demonstrating an improved version of the headset. Instead of wearing the headset over the ears, it was more like a hat, with 4 speakers at the end of support rods spaced about 5 cm away from the ears. While obviously impractical, it was presented as some kind of demonstration of how a quad headset should sound. I didn't try it. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#47
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Sony SL-2700 Betamax
William Sommerwerck wrote: You do know that Ampex started the development of VHS before they sold out to a consortium of japanese companies to raise much needed funds for their financial survival? Ampex wanted to make a cheap, scaled down version of their existing 1% 2" tape systems, to sell at an affordable price for consumers but ran into cash flow problems. That's new to me. I don't see why Japanese companies aren't capable of designing poor-quality products on their own. (RCA had been working on a consumer video recorder for years, but felt it wouldn't be marketable until it hit the same price point as color TV -- $500.) The Betamax machines I worked on treated the tape a lot worse than VHS. That's not altogether surprising. Beta pulled the tape into an elongated loop around the drum, to isolate its motion -- which is why Beta has less line jitter. Some had the tape sliding against itself to simplify the loading and unloading. I'm not sure I understand. the tape was wrapped around the drum, then around a guidepost. The back side of the film was dragged across the outside of the film on its way back into the cartridge. VHS pulled the tape around the drum from both sides, and didn't have some of the tape handling problems of the Beta machines. We offered U-matic for our public access channel at United Video Cablevision in Cincinnati. One church paid to air their services but insisted on beta. They supplied a huge, Sony beta deck. It, and the video quality was crap. The chroma was unstable, and the sync levels didn't meet FCC specs, so I had to let the dark, muddy video go out. It was a minority church that had screamed racism, because 'Only a white church can afford U-matic!!!' Having seen both in use in a broadcast station, the cheap VHS was much better than any Beta, other than the overpriced ENG version that only got 20 minutes per tape. All Sony machines needed a TBC to meet FCC requirements, but I could feed a $79 VHS tape into our Vital Industries Squeezezoom and get a picture that was stable enough to broadcast. You are one of the most-knowledgeable people (about anything) I've ever met, but here I have to say "No way, José." VHS has serious time-base problems. You don't understand what the SqueezeZoom was. It was the first broadcast quality Digital Video Effects system on the market. It sold for $250,000, and was made in Gainesville, Florida. It had two pages of digitized video, and built one while displaying the other. Considering that it used a Z80B processor and slower than dirt interleaved RAM, it was an amazing piece of equipment. It filled a full relay rack, and the +5 volt power supply was a linear three phase monster with a clean 1,000 amp output. It could take the output of a good VHS machine with no problem, but I never saw a Beta that it liked. You've likely seen one of it's best known uses at the end of the old Sonny & Cher show, when they walked out in each set of costumes from each skit, one after another. The images were combined into a video with all of them with no obvious degrading of the image. It was the first time it could be done in post production, with 2" video tape instead of shooting film and sending it to and outside company for optical work. Studios were begging for a chance to get one as fast as possible. BTW: The custom video ADC was over $1400. I first noticed this the early 80s when I was scanning a late-night show I'd recorded * -- why was the picture visibly sharper than in normal play? I looked closely and saw the reason -- severe line jitter. When scanning, there was either less of it (for the same reason analog recorders have less flutter at higher speeds), or the eye did a better job of averaging the errors. Just as I judge audio equipment by what I hear, I judge video equipment by what I see. When VHS recordings have obvious time-base problems -- what am I supposed to conclude? * The machine was a high-end RCA-branded Panasonic. |
#48
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Sony SL-2700 Betamax
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#49
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Sony SL-2700 Betamax
William Sommerwerck wrote:
"Cydrome Leader" wrote in message ... The movie folks do a really half assed job with surround sound is the short version of the story. That might be true. But I've spent many years listening to orchestral recordings enhanced with surround -- either from the recording itself, or a hall synthesizer -- and the improvement is huge. They probably do those recordings correctly, and the audience for such recording will care. I've seen pretty recent movies where the surround sound effects are completely random and pointless. One movie has surround sound for a bird flying around, and it had nothing to do with the scene at all. It's like there was a budget for 30 seconds of surround sound and somebody played some canned sound effects to meet a quota. Then or couse when people were being chased around in the woods and murdered there was no surround sound. That would have been the perfect time for such effects- hearing some twigs snap over here or there. Circa 1980, I had a really high-quality quad system, with Lux electronics and Infinity speakers. People -- including a hi-fi dealer -- said "I don't like quad, but I like your system". How were those extra channels added and extracted from the regular two channel recordings, other than with one of those boxes? |
#50
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Sony SL-2700 Betamax
"Cydrome Leader" wrote in message ...
William Sommerwerck wrote: "Cydrome Leader" wrote in message ... The movie folks do a really half-assed job with surround sound is the short version of the story. That might be true. But I've spent many years listening to orchestral recordings enhanced with surround -- either from the recording itself, or a hall synthesizer -- and the improvement is huge. They probably do those recordings correctly, and the audience for such recording will care. Absolutely. Then, of course, when people were being chased around in the woods and murdered there was no surround sound. That would have been the perfect time for such effects -- hearing some twigs snap over here or there. Point well-taken. Movies often miss the opportunity to create a truly immersive experience. Circa 1980, I had a really high-quality quad system, with Lux electronics and Infinity speakers. People -- including a hi-fi dealer -- said "I don't like quad, but I like your system". How were those extra channels added and extracted from the regular two channel recordings, other than with one of those boxes? I had a variety of sources and processors. At the top was discrete open-reel tape, which produced the most-spectacular consumer sound, until multi-ch SACD came along. (I still have the tapes and an Otari quad deck.) It is unfortunate that Sony has refused to reissue its huge library of Columbia surround recordings on SACD. For quad phonograph records, there was the Audionics Space & Image Composer, an advanced SQ decoder that could wrap stereo recordings around you, often to great effect. I also had an Ambisonic decoder for Ambisonic recordings. It could do things similar to the Audionics, without requiring logic circuitry, and did a superb job of ambience extraction. For stereo recordings, I had an audio/pulse Model One, the first consumer digital ambience device. It didn't generate high echo density, but used tastefully, it could greatly enhance the sense of space. (I later replaced it with the improved audio/pulse 1000.) My current system includes the JVC XP-A1000 and Yamaha DSP-3000 hall synthesizers. These are modeled on real halls (such as the Concertgebouw). You can pick an appropriate hall (concert, recital, cathedral, opera, stadium), then tweak the settings (if you wish) to fine-tune the sound to match the recording's ambience. These devices are so natural-sounding, you cannot hear them working until you shut them off. I have a 6.1 system (no center speaker) with Apogee speakers and Curl amplification. There is no excuse to listen in two channels. Stereo is technically and aesthetically obsolete. |
#51
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Sony SL-2700 Betamax
On 5/30/2013 11:39 AM, Jeff Liebermann wrote:
On Wed, 29 May 2013 18:53:34 -0400, Smarty wrote: On 5/29/2013 12:59 PM, Jeff Liebermann wrote: On Wed, 29 May 2013 15:28:34 +0000 (UTC), Cydrome Leader wrote: If fuses blew on the amp, I'd not be in a hurry to start replacing them. I'd probably disable channels in the surround decoder. Chuckle. I have an old Heathkit AA-2010 quad channel amplifier. http://www.audioasylumtrader.com/ca/ca.html?ca=23000 I'm down to one channel now, as the other three have blown up over the years. When the last channel dies, I'll probably fix it and start over. My ears are somewhat screwed up, so quad sound never did anything for me. In the early 1970's, I attened an AES (Audio Engineering Society) convention, where the hot topic was quadraphonic everything. I tried on quad earphones and heard nothing interesting. I listened to a serious discussion between "experts" over whether the listener wants concert hall realism, which meant sitting in front of the orchestra in stereo, or whether he wants to be "immersed" in the sound, which meant sitting in the middle of the orchestra in quad. Meanwhile, the movie theaters were having a bit of a problem with quad sound, which tended to produce dead spots. Subsequent to the original release of quad headphones, in the late 60s, considerable research was done on ear / brain localization and spatial imaging, funded in part by the Air Force / DARPA (to facilitate heads up display direction of arrival cues for pilots being fired upon from 360 degrees in azimuth). Some seminal work was done at the University of Darmstadt, Germany, the prior art upon which Bob Carver's original "sonic hologram' patent was granted. http://en.wikipedia.org/wiki/Bob_Carver The technical significance of the findings was the intra-aural spacing of the typical human and the resulting time difference of arrival from the earlier to the later ear, combined with the comb filter created by the external ear's ridge structure (pinnae) allowed the brain to build a mental map of where things arrived from acoustically. A given angle of arrival in azimuth and elevation at a given frequency would have a learned interpretation of where it arose from. This was in addition to the reverb decay times and spectra influencing / defining the enclosed space in which the audio was captured / simulated. The bottom line was that headset design could not inherently replicate the intra-aural delays and especially the comb filter results accurately for all individuals, since each of us has a unique set of parameters. Partially successful alternatives such as binaural recording and playback have overcome this to some extent but not fully. Thanks. That explains why I didn't hear anything resembling quadraphonic sound. My ears are bad, but not that bad. There were others in the group that claimed the quad headset was wonderful sounding but they would be fiddling with the controls, or moving the headset around trying to "improve" the experience. I also noticed a few puzzled looks as they were playing with the headset. I few shows later, someone demonstrating an improved version of the headset. Instead of wearing the headset over the ears, it was more like a hat, with 4 speakers at the end of support rods spaced about 5 cm away from the ears. While obviously impractical, it was presented as some kind of demonstration of how a quad headset should sound. I didn't try it. The spacing of the drivers away from the ears did achieve a reasonable degree of rear channel and front to back spatial imaging, since it could exploit the outer ears and their frequency dependent filtering. It is not a coincidence that "Mother Nature" chose the spacing of the ridges of the outer ear to act as reflectors and attenuators precisely in the acoustical wavelengths where we perceive high frequency audio in space. Think of the outer ear as a Yagi, a beam former, or a synthesized aperture and you begin to get the idea nature has provided foe eons not just on humans. The manikin heads designed for holding binaural recording mikes will usually provide a generic version of these same folds. Kinda works for everybody, but not very credibly compared to the real thing. The work one of my groups did for Wright Patterson Air Force Base in the early 80s used FFTs and convolvers to synthesize a transfer function which would place a sound source anywhere in the azimuthal and elevation planes so as to provide a rapid direction-of-arrival cue to warn against incoming missiles. Unlike Carver's "sonic hologram" which needed and used inter-aural cross-talk cancelling to make speakers appear much more like headphones in terms of left to right discrimination, the approach at SRL was intended to use pilot headphones and modify the perceived spatial presentation with an early DSP solution. Today's chip sets would have made the implementation a piece of cake, but 35 years ago the world was Z80's, 6502s, 6800s, etc. It was user calibrated, however, and this was the key to getting really accurate and repeatable directional cues. And it all came down to the comb filter coefficients and how they constructively and destructively combined the energy from a few hundred HZ up. |
#52
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Sony SL-2700 Betamax
On 5/30/2013 3:26 PM, William Sommerwerck wrote:
"Cydrome Leader" wrote in message ... William Sommerwerck wrote: "Cydrome Leader" wrote in message ... The movie folks do a really half-assed job with surround sound is the short version of the story. That might be true. But I've spent many years listening to orchestral recordings enhanced with surround -- either from the recording itself, or a hall synthesizer -- and the improvement is huge. They probably do those recordings correctly, and the audience for such recording will care. Absolutely. Then, of course, when people were being chased around in the woods and murdered there was no surround sound. That would have been the perfect time for such effects -- hearing some twigs snap over here or there. Point well-taken. Movies often miss the opportunity to create a truly immersive experience. Circa 1980, I had a really high-quality quad system, with Lux electronics and Infinity speakers. People -- including a hi-fi dealer -- said "I don't like quad, but I like your system". How were those extra channels added and extracted from the regular two channel recordings, other than with one of those boxes? I had a variety of sources and processors. At the top was discrete open-reel tape, which produced the most-spectacular consumer sound, until multi-ch SACD came along. (I still have the tapes and an Otari quad deck.) It is unfortunate that Sony has refused to reissue its huge library of Columbia surround recordings on SACD. Open reel was the best. JVC CD4 discrete disks were the worst...... Pre-recorded open reel tapes were few and expensive, but boy did they sound wonderful. For quad phonograph records, there was the Audionics Space & Image Composer, an advanced SQ decoder that could wrap stereo recordings around you, often to great effect. I also had an Ambisonic decoder for Ambisonic recordings. It could do things similar to the Audionics, without requiring logic circuitry, and did a superb job of ambience extraction. For stereo recordings, I had an audio/pulse Model One, the first consumer digital ambience device. It didn't generate high echo density, but used tastefully, it could greatly enhance the sense of space. (I later replaced it with the improved audio/pulse 1000.) My Audio Pulse hissed and made a lot of background noise. The pushbutton switch array also got intolerably noisey. The Advent SoundSpace was a huge improvement. My current system includes the JVC XP-A1000 and Yamaha DSP-3000 hall synthesizers. These are modeled on real halls (such as the Concertgebouw). You can pick an appropriate hall (concert, recital, cathedral, opera, stadium), then tweak the settings (if you wish) to fine-tune the sound to match the recording's ambience. These devices are so natural-sounding, you cannot hear them working until you shut them off. I have a 6.1 system (no center speaker) with Apogee speakers and Curl amplification. There is no excuse to listen in two channels. Stereo is technically and aesthetically obsolete. |
#53
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Sony SL-2700 Betamax
On 5/30/2013 3:26 PM, William Sommerwerck wrote:
"Cydrome Leader" wrote in message ... William Sommerwerck wrote: "Cydrome Leader" wrote in message ... The movie folks do a really half-assed job with surround sound is the short version of the story. That might be true. But I've spent many years listening to orchestral recordings enhanced with surround -- either from the recording itself, or a hall synthesizer -- and the improvement is huge. They probably do those recordings correctly, and the audience for such recording will care. Absolutely. Then, of course, when people were being chased around in the woods and murdered there was no surround sound. That would have been the perfect time for such effects -- hearing some twigs snap over here or there. Point well-taken. Movies often miss the opportunity to create a truly immersive experience. Circa 1980, I had a really high-quality quad system, with Lux electronics and Infinity speakers. People -- including a hi-fi dealer -- said "I don't like quad, but I like your system". How were those extra channels added and extracted from the regular two channel recordings, other than with one of those boxes? I had a variety of sources and processors. At the top was discrete open-reel tape, which produced the most-spectacular consumer sound, until multi-ch SACD came along. (I still have the tapes and an Otari quad deck.) It is unfortunate that Sony has refused to reissue its huge library of Columbia surround recordings on SACD. For quad phonograph records, there was the Audionics Space & Image Composer, an advanced SQ decoder that could wrap stereo recordings around you, often to great effect. I also had an Ambisonic decoder for Ambisonic recordings. It could do things similar to the Audionics, without requiring logic circuitry, and did a superb job of ambience extraction. For stereo recordings, I had an audio/pulse Model One, the first consumer digital ambience device. It didn't generate high echo density, but used tastefully, it could greatly enhance the sense of space. (I later replaced it with the improved audio/pulse 1000.) My current system includes the JVC XP-A1000 and Yamaha DSP-3000 hall synthesizers. These are modeled on real halls (such as the Concertgebouw). You can pick an appropriate hall (concert, recital, cathedral, opera, stadium), then tweak the settings (if you wish) to fine-tune the sound to match the recording's ambience. These devices are so natural-sounding, you cannot hear them working until you shut them off. I have a 6.1 system (no center speaker) with Apogee speakers and Curl amplification. I had Dayton Wrights, some Quad ESLs, now totally Martin Logan except for subs. There is no excuse to listen in two channels. Stereo is technically and aesthetically obsolete. |
#54
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Sony SL-2700 Betamax
I had Dayton Wrights...
I owned Dayton Wright //dynamic speakers// (trade name: Watson). Quite good. Had unbelievable subwoofers that got 15Hz -- solid -- out of a tiny box filled with SF6. (Sound familiar?) Why no one has "stolen" Wright's long-expired patents is beyond me. ...some Quad ESLs, now totally Martin-Logan except for subs. If ever I sell a screenplay, I will replace my belovéd Apogees with the big Martin-Logans. I don't know who you are, "Smarty", but its rare to meet an audiophile who understands the significance of surround. |
#55
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Sony SL-2700 Betamax
"How were those extra channels added and extracted from the regular two
channel recordings, other than with one of those boxes? " By summing the left and right channels and sending them to OP AMPS on the inverting inputs, resuling in the attenuation of the L+R component of both channels. By careful mixing, an audio engineer could do alot with that. A system called SQ came out which standardized the process somewhat and only nulled the mid to high ranges, leavng the bass relatively intact for the rear speakers which were ususally identical to the front speakers, unlike today.. Today, usually nothing under 100 Hz is sent to the rear. Those little satellite speakers couldn't reproduce it anyway. The standardization was simply the time constant of the feedback network and the actual amount of L+R attenuation. It was sort of licensed, and you could buy recording supposedly in "SQ", which meant that they were mixed in a way to take advantage of the standards. |
#56
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Sony SL-2700 Betamax
"How were those extra channels added and extracted from
the regular two channel recordings, other than with one of those boxes?" SQ was a full-range system without any frequency discrimination. The encoding and decoding were more-complex than simply adding and subtracting signals. |
#57
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Sony SL-2700 Betamax
On 5/30/2013 5:10 PM, William Sommerwerck wrote:
I had Dayton Wrights... I owned Dayton Wright //dynamic speakers// (trade name: Watson). Quite good. Had unbelievable subwoofers that got 15Hz -- solid -- out of a tiny box filled with SF6. (Sound familiar?) Why no one has "stolen" Wright's long-expired patents is beyond me. I am not familiar with those subs but you certainly have evoked my curiosity! Tiny boxes and 15 Hz --solid-- are not likely companions......... My brief flirtation with tiny box subs, ala Carver / Sunfire True Subs, was disappointing in that regard, although they did make a lot of subsonic energy considering their size. Now I am wondering what Wright's sub approach actually was. I still have a remaining Sunfire True Sub and some Carver Amazings here with quite an arsenal of low frequency drivers, but they have not been turned on in over a year. My Logan subs have been from Hsu Research, perhaps a bit pedestrian but very nice to listen to. ...some Quad ESLs, now totally Martin-Logan except for subs. If ever I sell a screenplay, I will replace my belovéd Apogees with the big Martin-Logans. If you are dreaming of owning the Logan Statement, I totally understand. The Apogees will be hard to improve upon. I don't know who you are, "Smarty", but its rare to meet an audiophile who understands the significance of surround. My vocation and avocation since the 1950s has been electrical engineering, all things electronic, ham radio, audio, video, computers, and the nearly endless array of gadgets which rely on electronics. A CES I attended in the 1960s exposed me to the first quad systems then emerging, and I had a small hand in working with a Toronto company to develop a gated 4 channel decoder using logic to steer rear channel content based on primitive rules from left and right amplitudes. Its intended market was movie theaters. It was very clear to me right from the start that reconstructing some information behind the listener had tremendous potential to improve the listening experience. "True" quad open reel was a joy to behold, and well miked and properly mastered content was just a quantum leap beyond anything I had ever heard. Even relatively small speakers allowed a credible and extremely engaging sound field. I think I was using AR or Rectilinear boxes at that time. There was a collection of open reel releases including Joni Mitchell from Verve or some similarly named company that were among my favorites. Carly Simon and James Taylor, married at the time, did a spectacular rendition of "Mocking Bird" in true 4 channel open reel that was another spectacular demonstration of the potential of surround. The classical releases were, for the most part, wonderful as well. As an old geezer, I can attribute my original surround passion to a Motorola "Vibrasonic" spring delay reverb installed in my 1962 Stingray. Other than the occasional microphonics which arose from the inevitable bumps in the road, it created a very satisfying presence and bloom which filled the passenger compartment. To this day I bemoan the absence of a really rich multichannel format for distribution of recorded music. The trend to mediocrity, especially mp3, is ironic given the low costs of analog to digital and digital to analog converters, storage, etc. If anything, the bar should be rising, but instead has been lowering. Was it PT Barnum who said that 'Nobody has ever gone broke underestimating the taste of the American public'? |
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Sony SL-2700 Betamax
On 5/30/2013 8:12 PM, William Sommerwerck wrote:
"How were those extra channels added and extracted from the regular two channel recordings, other than with one of those boxes?" SQ was a full-range system without any frequency discrimination. The encoding and decoding were more-complex than simply adding and subtracting signals. The more advanced systems essentially used voltage controlled amplifiers to synthesize the rear channels using amplitude and phase relationships from the front left and front right to make somewhat sensible decisions about when and where to steer energy into the rear channels. The notion of a "matrix" to construct the coefficients for the steering logic was developed, in which the VCAs and their control voltages had weighted, time-dependent control signals. Choosing appropriate time constants for the attack, release, etc. was artistic and musically dependent, and the eventually winning techniques such as Columbia SQ were noted for being comparatively gentle / subtle and without noticeable pumping or breathing. |
#59
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Sony SL-2700 Betamax
"Smarty" wrote in message ...
Now I am wondering what Wright's sub approach actually was. Sulfur hexafluoride, same as the 'stats. The woofers had a volume of about 2 cubic feet. When I put 15Hz into them, nothing was audible -- except for everything loose in the room rattling. These woofers had extremely low distortion -- around 2% at 20Hz. If you are dreaming of owning the Logan Statement, I totally understand. The Apogees will be hard to improve upon. Hard, but not impossible. There's an Australian company that makes a version with a true-ribbon titanium midrange. To this day I bemoan the absence of a really rich multichannel format for distribution of recorded music. The trend to mediocrity, especially mp3, is ironic given the low costs of analog to digital and digital to analog converters, storage, etc. If anything, the bar should be rising, It instead has been lowering. Was it PT Barnum who said that 'Nobody has ever gone broke underestimating the taste of the American public'? If by "rich", you mean "supporting a wide range of formats" (such as Ambisonics in addition to quadrifontal formats), I agree. But we have at least two high-quality uncompressed formats that aren't likely to go away -- multi-ch SACD and Blu-ray audio. |
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Sony SL-2700 Betamax
The more advanced systems essentially used voltage controlled amplifiers to
synthesize the rear channels using amplitude and phase relationships from the front left and front right to make somewhat sensible decisions about when and where to steer energy into the rear channels. The correct term is "isolate" or "extract", not synthesize. The rear channels are always present. Advanced decoders (such as Tate SQ and VarioMatrix QS) selectively cancel the interfering crosstalk, based on which channel is momentarily dominant. |
#61
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Sony SL-2700 Betamax
On 5/31/2013 3:05 PM, William Sommerwerck wrote:
The more advanced systems essentially used voltage controlled amplifiers to synthesize the rear channels using amplitude and phase relationships from the front left and front right to make somewhat sensible decisions about when and where to steer energy into the rear channels. The correct term is "isolate" or "extract", not synthesize. The rear channels are always present. Advanced decoders (such as Tate SQ and VarioMatrix QS) selectively cancel the interfering crosstalk, based on which channel is momentarily dominant. I would perhaps resort to semantic quibbling in this case, since the 'isolation' or 'extraction' of a left or right rear channel would presume that they had been encoded into the mix in some explicit way to begin with, and could thus be extracted using some reciprocal process or decoding scheme. The original front channels did not possess the bandwidth nor the dynamic range to permit separate channels to be encoded, and any scheme which claims to fold 4 channels into two and then magically permits the original 4 to be regenerated would need to use alternate modulation schemes, thereby rendering downward compatibility with existing stereo to be none existent. Fundamentally, you cannot take two channels of 20 KHz bandwidth and (let's say) 70 dB of dynamic range such as may be found in a standard LP record and somehow encode anything additional without either spoiling the original stereo L and R pair, eliminating conventional stereo playback, or creating a new and different encoding scheme from scratch. JVC approached the problem with adding an ultrasonic subcarrier and then modulating it, adding true additional channel capacity in the process (in much the same manner as FM monaural added FM stereo with its similar pilot and subcarrier multiplexor). Sadly, the JVC ultrasonic subcarrier imposed on the vinyl, groove, was both extremely fragile and very susceptible to noise, despite the specially shaped and designed stylus by Shibata which knew how to deal with it. My distinction between 'synthesize' and 'extract' really goes beyond mere semantics, and is quite explicit in communications theory in terms of signalling and channels, in that uncorrelated content in the 4 quad channels demands more than mere phase shift nulls, cancellations, or gated VCAs which temporarily steer energy from one place to another. The original 2 stereo channels could have encoded 4 true channels had engineers been allowed to sacrifice backward compatibility and trade bandwidth for dynamic range, for example. Or they could have incorporated some in-phase and quadrature method to modulate sidebands of a suppressed carrier or exalted carrier encoder (such as NTSC color) or used some (1960's vintage) TDMA mux approach. Or as a partial compromise, they could have put control tones / signals in the ultrasonic band above (let's say) 15 KHz and done some low pass filtering on the front channels and used the control tones to steer some rear VCAs. They opted to preserve quality and compatibility, and in doing so created a two channel mix from which extra channels could be synthesized, but the isolation / extraction of true rear channel could at best transpose out of phase information into rear channel output as if it were somehow supposed to be there in the first place. |
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Sony SL-2700 Betamax
The correct term is "isolate" or "extract", not synthesize. The rear
channels are always present. Advanced decoders (such as Tate SQ and VarioMatrix QS) selectively cancel the interfering crosstalk, based on which channel is momentarily dominant. I would perhaps resort to semantic quibbling in this case, since the 'isolation' or 'extraction' of a left or right rear channel would presume that they had been encoded into the mix in some explicit way to begin with, and could thus be extracted using some reciprocal process or decoding scheme. The original front channels did not possess the bandwidth nor the dynamic range to permit separate channels to be encoded, and any scheme which claims to fold 4 channels into two and then magically permits the original 4 to be regenerated would need to use alternate modulation schemes, thereby rendering downward compatibility with existing stereo to be none existent. This is absolutely true mathematically -- but it is not true psycoacoustically. The ear can be tricked. It is possible to have significant material on all four channels at the same time, with the resulting effect seeming fully "discrete". Actually, the "alternate modulation schemes" you refer to, do allow full backward compatibility, just as stereo FM broadcasts can be heard in mono without losing anything. Fundamentally, you cannot take two channels of 20 KHz bandwidth and (let's say) 70 dB of dynamic range such as may be found in a standard LP record and somehow encode anything additional without either spoiling the original stereo L and R pair, eliminating conventional stereo playback, or creating a new and different encoding scheme from scratch. Again, yes and no. SQ encodes the front left and front right channels as if they were conventional stereo, so they sound pretty much the same as they would on a stereo record -- or when an SQ disk is played in stereo. It is worth noting that Ambisonic UHJ encoding allows psychoacoustically correct playback without logic circuits. Of course, the availability of "discrete" delivery systems largely eliminates the issues of compatibility. |
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Sony SL-2700 Betamax
On 5/31/2013 5:08 PM, William Sommerwerck wrote:
The correct term is "isolate" or "extract", not synthesize. The rear channels are always present. Advanced decoders (such as Tate SQ and VarioMatrix QS) selectively cancel the interfering crosstalk, based on which channel is momentarily dominant. I would perhaps resort to semantic quibbling in this case, since the 'isolation' or 'extraction' of a left or right rear channel would presume that they had been encoded into the mix in some explicit way to begin with, and could thus be extracted using some reciprocal process or decoding scheme. The original front channels did not possess the bandwidth nor the dynamic range to permit separate channels to be encoded, and any scheme which claims to fold 4 channels into two and then magically permits the original 4 to be regenerated would need to use alternate modulation schemes, thereby rendering downward compatibility with existing stereo to be none existent. This is absolutely true mathematically -- but it is not true psycoacoustically. The ear can be tricked. Indeed it can. I was talking in the parlance of an electrical engineer, ultimately predicated upon the underlying mathematics of communications theory and its vocabulary. It is possible to have significant material on all four channels at the same time, with the resulting effect seeming fully "discrete". Yes, this is true, but this ear/brain trickery comes at a price. Engineers would not call this a discrete system since the effect is artificially created, aka 'synthetic'. Actually, the "alternate modulation schemes" you refer to, do allow full backward compatibility, just as stereo FM broadcasts can be heard in mono without losing anything. Only one alternate modulation schemes I mentioned does offer backwards compatibility, which is why JVC chose it for their CD4 vinyl LP system, at the expense of rapid wear-out and very noisy rear channels, mitigated somewhat by companding and severe filtering of highs in the rear. The other modulation schemes I described do not offer backwards compatibility unless the original front left and right channel performance is degraded. Fundamentally, you cannot take two channels of 20 KHz bandwidth and (let's say) 70 dB of dynamic range such as may be found in a standard LP record and somehow encode anything additional without either spoiling the original stereo L and R pair, eliminating conventional stereo playback, or creating a new and different encoding scheme from scratch. Again, yes and no. SQ encodes the front left and front right channels as if they were conventional stereo, so they sound pretty much the same as they would on a stereo record -- or when an SQ disk is played in stereo. It is worth noting that Ambisonic UHJ encoding allows psychoacoustically correct playback without logic circuits. Of course, the availability of "discrete" delivery systems largely eliminates the issues of compatibility. The kernel of your semantic distinction in that we are dealing with extraction and isolation of rear channel information which has been encoded and added into 2 standard front audio channels, ostensibly without compromise to the original front channel pair. I entirely agree that psychoacoustic techniques permit the illusion of 4 (or more) channels to be constructed in the listener's mind. The brain has a lot of adaptive power, and mp3 recordings with less than 15% of the originally encoded music are generally accepted as reasonable approximations to the original recording as well. Perhaps we hear what we want to hear or what we choose to hear. To the engineer however, the distinction between extracting an isolated signal which is independently signaled versus the synthesis of a derived signal which is not explicitly and discretely separable are two entirely different methods. The fact that the human brain can be fooled to think that the more complex discrete version can be adequately imitated by the less complex derived version really doesn't change the technical distinction between real versus synthetic. |
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Sony SL-2700 Betamax
To the engineer however, the distinction between extracting an isolated
signal which is independently signaled versus the synthesis of a derived signal which is not explicitly and discretely separable are two entirely different methods. The fact that the human brain can be fooled to think that the more complex discrete version can be adequately imitated by the less complex derived version really doesn't change the technical distinction between real versus synthetic. I never said it did. I object to the term "synthetic". |
#65
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Sony SL-2700 Betamax
On Fri, 31 May 2013 12:48:50 -0400, Smarty wrote:
On 5/30/2013 8:12 PM, William Sommerwerck wrote: "How were those extra channels added and extracted from the regular two channel recordings, other than with one of those boxes?" SQ was a full-range system without any frequency discrimination. The encoding and decoding were more-complex than simply adding and subtracting signals. The more advanced systems essentially used voltage controlled amplifiers to synthesize the rear channels using amplitude and phase relationships from the front left and front right to make somewhat sensible decisions about when and where to steer energy into the rear channels. The notion of a "matrix" to construct the coefficients for the steering logic was developed, in which the VCAs and their control voltages had weighted, time-dependent control signals. Choosing appropriate time constants for the attack, release, etc. was artistic and musically dependent, and the eventually winning techniques such as Columbia SQ were noted for being comparatively gentle / subtle and without noticeable pumping or breathing. I have been reading these posts about quad sound and it reminded me of my grandfather, William B. Snow, who did some pioneering work on stereo in large rooms, getting a patenet in 1938, and on binaural sound. When I was a young child he would let me listen to binaural recordings he made with the mannequin heads. I could hear him walking around behind me through the headphones, though what I was really hearing was a recording. As a young child I was amazed by the resemblance to live sound. He had a lab at his house with oscilloscopes and other sound equipment that was fascinating to me. He would have been very happy with the advancements made with sound processing since his death in '68. Eric |
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Sony SL-2700 Betamax
On 5/31/2013 5:49 PM, William Sommerwerck wrote:
To the engineer however, the distinction between extracting an isolated signal which is independently signaled versus the synthesis of a derived signal which is not explicitly and discretely separable are two entirely different methods. The fact that the human brain can be fooled to think that the more complex discrete version can be adequately imitated by the less complex derived version really doesn't change the technical distinction between real versus synthetic. I never said it did. I object to the term "synthetic". The word "synthetic" is not in any way used in a negative or derogatory fashion in the engineering context. Synthesis, analysis, and other such engineering terminology are understood to mean rather concrete things which may offend those who tend to thing of them in a more informal or colloquial way. The rear channel information in such systems as Columbia SQ is synthetic, having not been discretely processed as it would be in a system explicitly designed to capture and then reproduce such rear channel information. In fact, an SQ system could not localize a left rear only signal nor a right rear only signal without producing some artifacts in the front channels, given the non discrete nature of the method employed. It is an implementation distinction which may be noticed or may not, but it not at all like you make be thinking of if your objection views synthetic = "ersatz", unrealistic, etc. |
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Sony SL-2700 Betamax
The rear channel information in such systems as Columbia SQ
is synthetic, having not been discretely processed as it would be in a system explicitly designed to capture and then reproduce such rear-channel information. That is absolutely incorrect. In all four-channel matrix systems, there are four inputs and four outputs. A logic-directed, phase-cancellation decoder is capable of dynamically "separating" the front and back information. In fact, an SQ system could not localize a left-rear-only signal nor a right-rear-only signal without producing some artifacts in the front channels, given the non-discrete nature of the method employed. Of course it can, as assuredly as it can simultaneously localize left-front and right-front signals, without any artifacts in the rear channels. It can do this for //any two// isolated channels. The decoder cancels out their crosstalk in the other two channels. This breaks no laws of math or physics. It is an implementation distinction which may be noticed or may not, but it not at all like you make be thinking of if your objection views synthetic = "ersatz", unrealistic, etc. I own two hall synthesizers, which produce synthetic ambience -- which happens to sound very natural. |
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Sony SL-2700 Betamax
On 5/31/2013 10:18 PM, William Sommerwerck wrote:
The rear channel information in such systems as Columbia SQ is synthetic, having not been discretely processed as it would be in a system explicitly designed to capture and then reproduce such rear-channel information. That is absolutely incorrect. In all four-channel matrix systems, there are four inputs and four outputs. A logic-directed, phase-cancellation decoder is capable of dynamically "separating" the front and back information. In fact, an SQ system could not localize a left-rear-only signal nor a right-rear-only signal without producing some artifacts in the front channels, given the non-discrete nature of the method employed. Of course it can, as assuredly as it can simultaneously localize left-front and right-front signals, without any artifacts in the rear channels. It can do this for //any two// isolated channels. The decoder cancels out their crosstalk in the other two channels. This breaks no laws of math or physics. It is an implementation distinction which may be noticed or may not, but it not at all like you make be thinking of if your objection views synthetic = "ersatz", unrealistic, etc. I own two hall synthesizers, which produce synthetic ambience -- which happens to sound very natural. I have several hall synthesizers presently including a relatively elaborate Audyssey processor in my main system, and I have owned many going back to the AudioPulse 35 years ago (and its annoying hiss and pushbutton intermittents) and many, many since then. Many if not most of them sounded and presently sound extremely natural. And this discussion has absolutely NOTHING to do with their ability to create a convincing and natural and wonderful sound. I entirely and totally share your opinion and do not have any disagreement with your assessment of their performance from a psychoacoustics point of view whatsoever!! Had I been a critical reviewer of this equipment and been asked my opinion of how they sounded, I would totally express my vote of approval and confidence, and have, indeed voted many thousands of my dollars directly over quite a few decades supporting this very belief. Even my small audio system in a tiny small home office has a $2K Denon receiver with an Audyssey X32 processor because I totally enjoy the perceived effects of its natural surround sound. However........ I am now (and have been) exclusively talking from a technical, engineering viewpoint, and as one who is very qualified in this area. The various systems which do not provide separate and discrete independent channels for each of the 4 original channels cannot, do not, and will not separate and maintain independent information for each of the four channels unless each has its own distinct, isolated, channel. A channel has a very specific and very defined meaning to a communications engineer not only based on bandwidth and SNR but also its time domain / frequency domain characteristics, a snapshot of which can be portrayed in its transfer function, and measured entirely using both time and frequency domain techniques including Fourier and Laplace analysis. I spent 2 years in a Masters program learning this topic quite fully on top of the (4 courses of) required undergraduate electrical engineering course work required for this area. You might be convinced that some matrixed scheme of putting 4 audio channels into a 2 channel stereo medium can somehow permit the originals to be faithfully extracted, but I am here to tell you that you are entirely wrong. The more advanced version of SQ used gated, voltage controlled amplifiers not unlike the more recent Dolby ProLogic scheme to move out of phase information selectively to the rear. The encoder can and certainly does encode the rear channels to be out of phase so as to emphasize their rear presentation, BUT..............and this is the killer issue...........the original stereo mix already has out of phase information which itself conveys time differences attributable to front separation alone. The lack of separate and independent channels forces the scheme to "guess" at which elements of the signal structure represent true rear data, which represent original left to right phase differences, and how to use some form of demodulation to portray them. The appearance of multiple approaches using several competing matrixing, AGC, companding, and steering techniques and competing ways to trick the ear clearly illustrated the absence of a single correct solution, since the 4 into 2 back to 4 channel process is inherently very inexact. The decoder has no way to "cancel out crosstalk". The 2 channel phase information does not contain identifiable crosstalk since the front and rear are not orthogonal, and have no clock or other time reference to independently serve to distinguish front from back out of phase content versus left to right out of phase content. Were an ultrasonic clock to have been recorded (an approach considered as one potential solution versus an ultrasonic subcarrier used by JVC), and this clock used to time mux the analog stream, then there could indeed be a way to explicitly isolate separate channels, but at the expense of front channel bandwidth and signal to noise. In the subsequent digital era, these problems disappear, and bit pooling and TDMA or other muxing and sampling allow streams to be created where time can be used as a reliable reference to sort things out. In the early 1960s when these systems were being deployed (and I was in my graduate EE program) this was not an option. Try to imagine what a stereo capable LP would contain in order to create a left rear only output: If you had only left energy recorded, it would show up in the left channel regardless of phase. Left energy alone would have no phase difference to reference, and its absolute phase would either cause the left front speaker to move its cone first forward then back, or, if 180 degrees reversed, would move the cone in the opposite sense. Any phase angle you choose for conveying "front to back" for this simple example fails. If you want to build an encoder / decoder to use phase as a way to convey front / rear directionality, you can ***SYNTHESIZE*** an artificial reference frame, exaggerate the effect with VCAs and gating logic, and treat shorter phase shifts as if they belong to the front and longer phase shifts as if they belong to the rear. The ear can indeed be fooled, and this is fundamentally the way it was done. Lets go one step further and make an even more drastic engineering assumption. We are going to assume that the front speakers are spaced much closer to one another than the rear pair are spaced with respect to the front. We will then "guess" that phase shifts / time delays longer than the presumed short left to right delay are entirely attributable to rear delayed energy. We will choose an arbitrary cut off and declare that all delays longer than "X" degrees of phase shift are the result of rear channel content. This might even work were it not that 361 degrees of phase shift is entirely and totally indistinguishable from 1 degree of phase shift as far as analog processing is concerned. Phase only offers a brief impartial piece of evidence as encoded in this analog system. Could an advanced DSP be used to build an FFT waterfall and distinguish early and late energy more exactly. Yes, of course. But this has nothing to do with the way SQ, QS, Dolby ProLogic or any such primitive scheme worked in the 1960s. Did I ever say that SQ or other techniques of its ilk were bad, unnatural, or otherwise flawed. Not at all. I ask you please to not conflate how things work with how things sound. I am an engineer talking about how things work. |
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Sony SL-2700 Betamax
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#70
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Sony SL-2700 Betamax
On 5/31/2013 10:18 PM, William Sommerwerck wrote:
The rear channel information in such systems as Columbia SQ is synthetic, having not been discretely processed as it would be in a system explicitly designed to capture and then reproduce such rear-channel information. That is absolutely incorrect. In all four-channel matrix systems, there are four inputs and four outputs. A logic-directed, phase-cancellation decoder is capable of dynamically "separating" the front and back information. In fact, an SQ system could not localize a left-rear-only signal nor a right-rear-only signal without producing some artifacts in the front channels, given the non-discrete nature of the method employed. Of course it can, as assuredly as it can simultaneously localize left-front and right-front signals, without any artifacts in the rear channels. It can do this for //any two// isolated channels. The decoder cancels out their crosstalk in the other two channels. This breaks no laws of math or physics. Absolutely wrong answer! It most assuredly does violate both mathematical and physical constraints. You might want to take a look at the Ambisonics website where they state: Matrix quad tried to get the four original channels into two and back again, which is impossible. A sound panned around the control room in a circle (black) would be replayed as a flat ellipse by SQ" The flat ellipse shown in the Ambisonics reference is a typical result of using a matrix approach, and other matrix designs have other odd shapes, the Sansui QS matrix resulting in a heart-shaped / cardioid sound field. In any such example for any choice of matrix coefficients, the same result occurs, namely, the original directionality is lost, and the sound field changes its shape with frequency. In Sansui's design (later adopted for theater use as well) the rear channels effectively produce a single centered rear channel at the acute vertex of the cardioid. The brain and ear don't get any right rear to left rear directionality whatsoever. In the SQ matrix, there is very little front to back discrimination, with the virtual sound sources placed almost entirely to the left and right of the listener, imitating spatial depth by widening the front and adding hints to the rear. Both are entirely avoided using discrete analog techniques of the 1960s, as in ***4 DISCRETE CHANNELS***. The matrix methods are synthetic in that they synthesize an approximation to the discrete wavefronts, good enough to fool the majority of listeners, but by no means accurate or complete. http://www.ambisonic.net/pdf/ambidvd2001.pdf as well as the surrounding articles and introduction page for the Ambisonics approach. |
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Sony SL-2700 Betamax
"Smarty" wrote in message ...
We have the problem of two people who agree, arguing over the agreement. I am now (and have been) exclusively talking from a technical, engineering viewpoint, and as one who is very qualified in this area. The various systems which do not provide separate and discrete independent channels for each of the 4 original channels cannot, do not, and will not separate and maintain independent information for each of the four channels unless each has its own distinct, isolated, channel. That's what I said. Please re-read what I posted. I'll repeat it, though. In a matrixed quad system, a properly designed decoder can completely isolate one or two channels, when they are the only active channels. That is what I said, and I stand by it. (To put it mathematically -- you can solve for two unknowns -- but no more -- when you have two equations.) These is easily demonstrated with a single channel on a test disk, or by playing a conventional stereo recording through an advanced SQ decoder. Nothing comes out of the rear speakers. You might be convinced that some matrixed scheme of putting 4 audio channels into a 2 channel stereo medium can somehow permit the originals to be faithfully extracted, but I am here to tell you that you are entirely wrong. They can, under the conditions previously stated. The more advanced version of SQ used gated, voltage controlled amplifiers not unlike the more recent Dolby ProLogic scheme to move out of phase information selectively to the rear. The advanced SQ and QS decoders do not use "gated" amplifiers, which had been abandoned years earlier. I owned such a decoder (the Sony SQD-2020), and it sounded terrible, because it shut off channels with important material. I'm going to stop at this point and simply state -- in an objective and non-personal matter -- that you aren't familiar with how matrix and decoding work. I wish I had some material to offer, but a lot of my source material has been lost or misplaced over the years. If you'd to discuss this over the weekend, we can get together on the phone. |
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Sony SL-2700 Betamax
In fact, an SQ system could not localize a left-rear-only signal nor
a right-rear-only signal without producing some artifacts in the front channels, given the non-discrete nature of the method employed. Of course it can, as assuredly as it can simultaneously localize left-front and right-front signals, without any artifacts in the rear channels. It can do this for //any two// isolated channels. The decoder cancels out their crosstalk in the other two channels. This breaks no laws of math or physics. Absolutely wrong answer! It most assuredly does violate both mathematical and physical constraints. You might want to take a look at the Ambisonics website where they state: Matrix quad tried to get the four original channels into two and back again, which is impossible. A sound panned around the control room in a circle (black) would be replayed as a flat ellipse by SQ" READ WHAT I SAID, rather than what you think I said. |
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Sony SL-2700 Betamax
On 6/1/2013 9:03 AM, William Sommerwerck wrote:
"Smarty" wrote in message ... We have the problem of two people who agree, arguing over the agreement. I am now (and have been) exclusively talking from a technical, engineering viewpoint, and as one who is very qualified in this area. The various systems which do not provide separate and discrete independent channels for each of the 4 original channels cannot, do not, and will not separate and maintain independent information for each of the four channels unless each has its own distinct, isolated, channel. That's what I said. Please re-read what I posted. I'll repeat it, though. In a matrixed quad system, a properly designed decoder can completely isolate one or two channels, when they are the only active channels. That is what I said, and I stand by it. (To put it mathematically -- you can solve for two unknowns -- but no more -- when you have two equations.) These is easily demonstrated with a single channel on a test disk, or by playing a conventional stereo recording through an advanced SQ decoder. Nothing comes out of the rear speakers. You might be convinced that some matrixed scheme of putting 4 audio channels into a 2 channel stereo medium can somehow permit the originals to be faithfully extracted, but I am here to tell you that you are entirely wrong. They can, under the conditions previously stated. The more advanced version of SQ used gated, voltage controlled amplifiers not unlike the more recent Dolby ProLogic scheme to move out of phase information selectively to the rear. The advanced SQ and QS decoders do not use "gated" amplifiers, which had been abandoned years earlier. I owned such a decoder (the Sony SQD-2020), and it sounded terrible, because it shut off channels with important material. I'm going to stop at this point and simply state -- in an objective and non-personal matter -- that you aren't familiar with how matrix and decoding work. I wish I had some material to offer, but a lot of my source material has been lost or misplaced over the years. If you'd to discuss this over the weekend, we can get together on the phone. I will begin with your last and most offensive comment first. I am not at liberty to describe this in detail given certain non disclosure agreements, but I will leave you with the opportunity to research Peter Scheiber and the patent rights sold to Dolby for the design and implementation of original matrixing audio technology ultimately sold to Columbia to become SQ. I can only state a single comment, which is that Mr. Scheiber, a musician, and non engineer, holds the original patent, but relied on a certain graduate university student to develop and build his design concept. I will leave it to your fertile and most ad hominem imagination to figure out who that graduate student was. And I will remind you of my original introduction to this topic earlier in this very same thread by stating that I had first worked in Toronto on a matrixing audio encoder design for theater use starting in the 1960s. Since you have already amply demonstrated an exquisite knack for putting two and two together and getting two, I will now briefly summarize your conclusion that we are supposedly violently agreeing upon. If you are now stating that a 4 channel matrixing encode and decode system can merely handle two channels at a time, then you are now beginning to demonstrate and acknowledge their fundamental inability to extract and isolate 4 channels independently. If you are somehow trying to assert that by only doing two channels at a time, they somehow preserve these 2 channels correctly in the presence of any other energy arising from the other two channels whatsoever, you are utterly wrong. The point of this is that given a 4 channel input, the very best you can ever hope for are 4 poor imitations of the original 4 discrete signals. If you are somehow arguing that the method succeeds with simultaneous 4 channel input, you are incorrect. This type of solution is referred to by engineers as synthetic, since it uses a synthesis method to form approximations of actual things. Think "Moog synthesizer" if you cannot grasp the meaning in a more expansive way. I have merely stated that such systems as we have been discussing are "synthetic" and the notion that they somehow isolate and extract is technically wrong. |
#74
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Sony SL-2700 Betamax
William Sommerwerck wrote:
"Cydrome Leader" wrote in message ... William Sommerwerck wrote: "Cydrome Leader" wrote in message ... The movie folks do a really half-assed job with surround sound is the short version of the story. That might be true. But I've spent many years listening to orchestral recordings enhanced with surround -- either from the recording itself, or a hall synthesizer -- and the improvement is huge. They probably do those recordings correctly, and the audience for such recording will care. Absolutely. Then, of course, when people were being chased around in the woods and murdered there was no surround sound. That would have been the perfect time for such effects -- hearing some twigs snap over here or there. Point well-taken. Movies often miss the opportunity to create a truly immersive experience. Circa 1980, I had a really high-quality quad system, with Lux electronics and Infinity speakers. People -- including a hi-fi dealer -- said "I don't like quad, but I like your system". How were those extra channels added and extracted from the regular two channel recordings, other than with one of those boxes? I had a variety of sources and processors. At the top was discrete open-reel tape, which produced the most-spectacular consumer sound, until multi-ch SACD came along. (I still have the tapes and an Otari quad deck.) It is unfortunate that Sony has refused to reissue its huge library of Columbia surround recordings on SACD. Was "surround" at the time a true 4 channel recording? For quad phonograph records, there was the Audionics Space & Image Composer, an advanced SQ decoder that could wrap stereo recordings around you, often to great effect. I also had an Ambisonic decoder for Ambisonic recordings. It could do things similar to the Audionics, without requiring logic circuitry, and did a superb job of ambience extraction. For stereo recordings, I had an audio/pulse Model One, the first consumer digital ambience device. It didn't generate high echo density, but used tastefully, it could greatly enhance the sense of space. (I later replaced it with the improved audio/pulse 1000.) Out of these devices, which did true decoding of extra channels out of a a two channel recording? How did the encoded recordings sound if you skipped the decoders? With old tape decks and Dolby noise reduction, it didn't matter on playback. My current system includes the JVC XP-A1000 and Yamaha DSP-3000 hall synthesizers. These are modeled on real halls (such as the Concertgebouw). You can pick an appropriate hall (concert, recital, cathedral, opera, stadium), then tweak the settings (if you wish) to fine-tune the sound to match the recording's ambience. These devices are so natural-sounding, you cannot hear them working until you shut them off. I have a 6.1 system (no center speaker) with Apogee speakers and Curl amplification. There is no excuse to listen in two channels. Stereo is technically and aesthetically obsolete. unless all your recordings are only available in plain stereo. I actually had a really hard time locating a surround sound audio test file to use with a WD Live video/audio playing device. My surround decoder has the generate noise on each channel test for setting up speakers, but that doesn't tell you if it really understands the signals coming out of the modern media player. |
#76
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Sony SL-2700 Betamax
"Cydrome Leader" wrote in message ...
Was "surround" at the time a true 4 channel recording? I'm not sure what you mean by "true". Matrixed recordings were considered four-channel recordings. The first modern surround recordings came from AR/Vanguard. They were called "surround stereo", I believe. After that, the term "quadraphonic" was adapted. (And please don't complain about mixing Greek and Latin. "Dinosaur" is a similar hybrid.) Out of these devices, which did true decoding of extra channels out of a two channel recording? Strictly speaking, none of them, as two-channel recordings, by definition, do not have extra channels to be decoded. However, some of the devices -- such as the Space & Image Composer and the Ambisonic decoders -- could manipulate 2-channel recordings to wrap the sound around you, or extract ambience, or both at the same time. How did the encoded recordings sound if you skipped the decoders? With old tape decks and Dolby noise reduction, it didn't matter on playback. Generally, they sounded pretty much like regular stereo. The rear channels weren't lost or diminished in level -- they simply appeared in the front. (With SQ recordings, LR and RR often appeared slightly "outside" the front speakers.) Unfortunately, recordings with ambience in the rear channels tended to sound overly reverberant in stereo. EMI was obliged to reduce the ambience levels. There is no excuse to listen in two channels. Stereo is technically and aesthetically obsolete. Unless all your recordings are only available in plain stereo. Not at all. Your control unit probably has surround modes to enhance stereo recordings. And hall synthesizers can be bought on eBay. I actually had a really hard time locating a surround sound audio test file to use with a WD Live video/audio playing device. My surround decoder has a noise generator to identify the channels when setting up speakers, but that doesn't tell you if it really understands the signals coming out of the modern media player. If the program source is "discrete", then there shouldn't be a problem. * Matrixed material generally requires manual mode selection. Lossy-compressed materials (such as the various Dolby Digital formats) are //supposed// to be correctly recognized by your control unit. Regardless, if playback doesn't seem correct, try forcing the controller to different modes (if it allows this). I agree that a test disk would be useful. * With one exception. Some Blu-ray players won't properly output channels 6 and 7 unless you change one of the player's default settings. |
#77
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Sony SL-2700 Betamax
"Cydrome Leader" wrote in message ...
I've always wondered what that was. I seem to think I've seen that on laserdiscs, and just checked mine, but none have it, not that I'd be able to play it back correctly anyways. The explanation given was almost completely incorrect. |
#78
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Sony SL-2700 Betamax
William Sommerwerck wrote:
"Cydrome Leader" wrote in message ... Was "surround" at the time a true 4 channel recording? I'm not sure what you mean by "true". Matrixed recordings were considered four-channel recordings. The first modern surround recordings came from AR/Vanguard. They were called "surround stereo", I believe. After that, the term "quadraphonic" was adapted. (And please don't complain about mixing Greek and Latin. "Dinosaur" is a similar hybrid.) Out of these devices, which did true decoding of extra channels out of a two channel recording? Strictly speaking, none of them, as two-channel recordings, by definition, do not have extra channels to be decoded. However, some of the devices -- such as the Space & Image Composer and the Ambisonic decoders -- could manipulate 2-channel recordings to wrap the sound around you, or extract ambience, or both at the same time. How did the encoded recordings sound if you skipped the decoders? With old tape decks and Dolby noise reduction, it didn't matter on playback. Generally, they sounded pretty much like regular stereo. The rear channels weren't lost or diminished in level -- they simply appeared in the front. (With SQ recordings, LR and RR often appeared slightly "outside" the front speakers.) Unfortunately, recordings with ambience in the rear channels tended to sound overly reverberant in stereo. EMI was obliged to reduce the ambience levels. There is no excuse to listen in two channels. Stereo is technically and aesthetically obsolete. Unless all your recordings are only available in plain stereo. Not at all. Your control unit probably has surround modes to enhance stereo recordings. And hall synthesizers can be bought on eBay. This may sound weird, but I'm against meddling with recordings and using weird made-up affect that have nothing to do with the original recording. If it wasn't in the recording, I don't want to hear it. Not everything was recorded in a cathedral either. If I can hear the strange defects in a recording as it was made and mixed, that's plenty exciting for me. Again, this all depends on the type of music as well. Wether or not heavily produced studio recording from Yes sounds better in a "concert hall" or "jazz club" setting is questionable. I actually had a really hard time locating a surround sound audio test file to use with a WD Live video/audio playing device. My surround decoder has a noise generator to identify the channels when setting up speakers, but that doesn't tell you if it really understands the signals coming out of the modern media player. If the program source is "discrete", then there shouldn't be a problem. * Matrixed material generally requires manual mode selection. Lossy-compressed materials (such as the various Dolby Digital formats) are //supposed// to be correctly recognized by your control unit. Regardless, if playback doesn't seem correct, try forcing the controller to different modes (if it allows this). I agree that a test disk would be useful. * With one exception. Some Blu-ray players won't properly output channels 6 and 7 unless you change one of the player's default settings. I had to screw with all the settings for type of sourround signals and how they were outputted (hdmi/toslink or both) and what format and compatibility modes to output to the decoder. The decoder only has a few vague settings. Eventually it all worked, but the bluray player needed firmware updates. |
#79
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Sony SL-2700 Betamax
William Sommerwerck wrote:
"Cydrome Leader" wrote in message ... I've always wondered what that was. I seem to think I've seen that on laserdiscs, and just checked mine, but none have it, not that I'd be able to play it back correctly anyways. The explanation given was almost completely incorrect. The explanation for SQ was wrong? |
#80
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Sony SL-2700 Betamax
"Cydrome Leader" wrote in message ...
William Sommerwerck wrote: Your control unit probably has surround modes to enhance stereo recordings. And hall synthesizers can be bought on eBay. This may sound weird, but I'm against meddling with recordings and using weird made-up affect that have nothing to do with the original recording. If it wasn't in the recording, I don't want to hear it. Not everything was recorded in a cathedral either. If I can hear the strange defects in a recording as it was made and mixed, that's plenty exciting for me. That's not weird. Over the years I've learned that most "enhancements" do nothing to truly improve the sound. Worse, the better the playback equipment, the more the enhancements become audible as unmusical changes. Of course, two-channel recording is fundamentally limited in its ability to convey directionality and spatiality. This might not be important if you're listening to multi-miked studio recordings, but it /is/ important when the music was (or should have been) recorded in an appropriate acoustic space. The Carver Sonic Hologram actually does work -- at least with simply-miked recordings. (I've had little experience with other crosstalk cancellers, which might or might not work.) An Ambisonic decoder can "extract" the ambience from a well-made recording and present it in a very natural-sounding manner. Of course, such devices require sending the program through a processor, which to an audiophile is generally a no-no. That's the beauty of a hall synthesizer -- the generated ambience is played through four additional speakers, and the original recording is left untouched. Again, this all depends on the type of music as well. Wether or not heavily produced studio recording from Yes sounds better in a "concert hall" or "jazz club" setting is questionable. What about "Stadium"? grin I had to screw with all the settings for type of sourround signals and how they were outputted (HDMI/TOSlink or both) and what format and compatibility modes to output to the decoder. The decoder only has a few vague settings. Eventually it all worked, but the Blu-ray player needed firmware updates. That's not surprising. Consumer photographic and electronics products have become incredibly complex, and the idiots (I use the word deliberately, because they are idiots) who write the user manuals neither understand the products nor how to explain their use to the reader. I have long considered starting a class-action suit against the major manufacturers for their lousy manuals. |
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