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vinylcollector
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Post subject: Quadraphonic 4 channel decoder Posted: 12 Oct 2012, 20:22 |
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Joined: 25 Jul 2010, 19:45 Posts: 585 Location: Canada Has thanked: 0 time Been thanked: 3 times
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Well I know this isn't a Fosgate, but today I received a Realistic Quadraphonic 4 channel decoder. I won't have a chance to try it out till later today, but has side wood pannels, made in Japan, and was still brand new vintage in the box for only 58.00 so I couldn't go wrong. It was missing the instructions, but that shouldn't be a problem. Can't wait to hook it up to my LD player to see how sounds. and see if I can one of the SQ matrixed laserdiscs. Here are some pics to see what it looks like.
Last edited by vinylcollector on 22 Mar 2013, 01:34, edited 2 times in total.
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laserbite34
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Post subject: Re: Quadraphonic 4 channel decoder Posted: 13 Oct 2012, 00:16 |
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Joined: 10 Oct 2006, 17:10 Posts: 3742 Location: United Kingdom Has thanked: 5 times Been thanked: 4 times
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That's a good buy. I can't comment on it I haven't had first-hand listening experience with SQ-II? Is it true discrete that is differences between the front stereo and rear stereo as I have never owned on or even come across one.
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vinylcollector
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Post subject: Re: Quadraphonic 4 channel decoder Posted: 15 Oct 2012, 04:37 |
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Joined: 25 Jul 2010, 19:45 Posts: 585 Location: Canada Has thanked: 0 time Been thanked: 3 times
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Having now hooked it up, I have tested it out and reading up on mine. I have nothing to test the discrete out, but from what I read mine does not have full logics as some of the other Quadraphonic decoders had.
The vintage amp I'm using is a Pioneer SA-7500 II with 4 speakers, but only has basic left/right channel input. Some of the older amps had 4 channel inputs to connect the decoder directly to it (front left/right and rear left/right) So what I did was use "Y" splitters, and put the left front and back into the left channel of my amp, and the right front and back into the right channel so I got the 4 channel sounds that way. The other proper way would be to use 2 amplifiers, one amp for the 2 front speakers, and the other amp for the 2 rear speakers.
I tried my Star Trek The Borg collection LD, my Atlantis (Luc Besson) both through SQ mode and gave a nice sound effect. The 2ch stereo enhance button was good too. Then I tried The Ventures Live in LA (1981 analog) and used the Stereo enhance which wasn't bad either. On the SQ mode, sounded like being right in the concert at a distance from the stage.
So I'd say if you can find one of these decoders cheap price it's fun to play with.
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disclord
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Post subject: Re: Quadraphonic 4 channel decoder Posted: 15 Oct 2012, 05:24 |
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Joined: 22 Jun 2010, 21:12 Posts: 1616 Location: Plattsburg, Missouri. USA Has thanked: 0 time Been thanked: 11 times
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I've been meaning to answer your PM - the decoder you bought doesn't decode SQ accurately - it's non-logic and gives no more than 4 db of channel separation, which is basically none at all. Only the Sony Full Logic and Layfette SQ-W gain riding units decode SQ OK and SQ is decoded correctly via Matrix Multiplication only by the Audionics Space and Image Composer and especially the Fosgate Tate II 101A. In fact, the Fosgate is the only SQ decoder that accurately decodes all directions, including interior pans, with up to 50 db of channel separation and can decode 3 directions at once due to the 3 axis detector. (the Audionics couldn't decode the side or interior directions correctly due to its detector and early Tate chip) Aphex made a sophisticated gain riding SQ decoder in 1985, but it performed very poorly giving only 10db of separation. It decoded Dolby Surround well though.
Sadly, if you want to hear SQ correctly, you need the Fosgate 101A - their prices have been coming down lately, selling for around $500 instead of the $1000 or so a few years ago.
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disclord
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Post subject: Re: Quadraphonic 4 channel decoder Posted: 18 Dec 2012, 19:11 |
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Joined: 22 Jun 2010, 21:12 Posts: 1616 Location: Plattsburg, Missouri. USA Has thanked: 0 time Been thanked: 11 times
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dewdude wrote: The only Quad LP format that was worth anything was the CD-4 system. Its a true discreet system that uses mid/side matrixing with a 50khz carrier. The quality is outstanding.
SQ, QS and others weren't quite true discreet. I believe the SQ had some signaling information, but as stated; you need the full logic decoders. Everything else is modified Hafler.
Good news for CD-4 is if you have a shibata stylus and a 192khz ADC; its theoritcally possible to extract the differences with Matlab...or so I've tried. CD-4 modulated the L F-B & R F-B difference information as compressed (noise reduced) FM/PM/FM signals on a 30 kHz carrier that had unequal sidebands that extended down to 20kHz and up to 45 kHz. The baseband left and right sum signals were recorded normally except their high end was restricted to 15kHz to allow a guardband between the baseband and modulated FM carrier signal. The noise reduction used on the carrier signals was JVC's dual band ANRS (Automatic Noise Reduction System) that was somewhat like Dolby B and A-type NR. In fact, Dolby sued JVC and JVC lost and had to pay royalties to Dolby. The Neutrix I &II groove predistortion system was used in mastering the CD-4 LP to allow the Shibata stylus to track the grooves with much greater accuracy. In addition, a special vinyl was used so the carrier signal didn't get worn off the LP. CD-4 was a tricky system - I mean the LP was carrying an FM radio signal! But when set up right and using one of the few good demodulators, CD-4 could sound amazing. I have some DVD-Audio discs made from my CD-4 soundtracks to Jaws and Earthquake - mastered at 96 kHz, 24-bit, they sound simply incredible. And on Earthquake JVC used the Sensurround Rumble Generator to create the quake effects and the rumble extends down to 16 Hz. On the standard stereo soundtrack the rumble was from tape and not quite so deep. Both Jaws and Earthquake on CD-4 used the actual music recordings used in the film and were not rerecordings like the official soundtrack issues. SQ encoded the rear channels by phase shifting them by + & - 90 degrees and then mixing them with the main front channels which had a reference 0 degree phase shift. With an advanced vector cancellation (Matrix Multiplier) decoder, SQ could sound as discrete as CD-4. But most SQ decoders were simple gain riding units that raised or lowered the channels level to give the impression of separation. The most advanced SQ decoding system, the Tate Directional Enhancement System, used in the Fosgate Tate II 101A and the Audionics Space & Image Composer, is a wonder to listen to - it even synthesizes 4 channels from stereo albums and it sounds like real quad. Until 1986 Dolby Labs used the Tate chips, with extensive modifications to make them work with Dolby's surround matrix, in their Dolby stereo decoders to decode the stereo surround soundtracks of films. When they couldn't get the Tate chips anymore they developed their own, now well known, Pro-Logic system. Shure copied the logic action of the Dolby Modified Tate chip decoding performance to make their own Acra-Vector surround decoders and also introduced their own surround encoding system, Shure Sterosurround, which was used by CBS and on many, many LaserDisc's, even though they carry the Dolby Surround logo. Shure went a bit beyond Dolby decoding though to allow two opposite directions to be decoded at the same time, which gives a much more discrete sounding presentation. I use the Shure HTS-5300 for LaserDisc's and DVD's that are Dolby or UltraStereo since it decodes better than Pro-Logic or PL-II. The Shure decoders are dirt cheap on eBay now so I have 2 of them. Plus, they have the best directional channel display ever invented. For QS recordings, which were encoded somewhat like SQ, but not compatible, you need a Sansui Vario-Matrix decoder. No other QS decoder will do. BUT, if you have some QS LP's Dolby PL-II will decode them if you put the PL-II into the Music mode, Panorama mode ON and the width control all the way to the back. Then it will decode QS perfectly. It's just a strange quirk of Dolby Pro-Logic II.
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publius
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Post subject: Re: Quadraphonic 4 channel decoder Posted: 18 Dec 2012, 20:07 |
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Joined: 23 Sep 2003, 18:14 Posts: 1391 Location: United States Has thanked: 39 times Been thanked: 21 times
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disclord wrote: CD-4 modulated the L F-B & R F-B difference information as compressed (noise reduced) FM/PM/FM signals on a 30 kHz carrier that had unequal sidebands that extended down to 20kHz and up to 45 kHz. The baseband left and right sum signals were recorded normally except their high end was restricted to 15kHz to allow a guardband between the baseband and modulated FM carrier signal. The noise reduction used on the carrier signals was JVC's dual band ANRS (Automatic Noise Reduction System) that was somewhat like Dolby B and A-type NR. In fact, Dolby sued JVC and JVC lost and had to pay royalties to Dolby. The Neutrix I &II groove predistortion system was used in mastering the CD-4 LP to allow the Shibata stylus to track the grooves with much greater accuracy. In addition, a special vinyl was used so the carrier signal didn't get worn off the LP. Mind you, the bandwidth limitation was pretty unimportant, since it was difficult to get much response above 12 kHz on any but the best LPs, with the best playback equipment — although there were some discs pressed about the same time, using the same vinyl formulation as for CD-4 (or similar to it), which when played back with a Shibata or good elliptical stylus with a suitable cartridge would do it. But CD-4 really skated on the edge of what was technically possible with that kind of system. I am still irritated that the discrete 4-channel option on the Compact Disc was never implemented. It's in the specification, same sampling frequency & bit depth as the 2-channel option, a little more than half the running time (due to having slightly less subcode data) ; but there has never been, to my knowledge, a player built which would play a disc encoded that way, or software released to allow encoding such a disc, & my understanding is that if you generate a SPDIF stream with the 4-channel flag set, most equipment will reject it. Of course, that would also have allowed sending 4-channel audio from a MUSE decoder on one digital connexion instead of two… the total non-support of multi-channel consumer digital audio until the introduction of AC-3 & dts continues to bother me.
_________________ MUSE decoder information and user guides LD player connexion guide
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disclord
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Post subject: Re: Quadraphonic 4 channel decoder Posted: 18 Dec 2012, 20:50 |
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Joined: 22 Jun 2010, 21:12 Posts: 1616 Location: Plattsburg, Missouri. USA Has thanked: 0 time Been thanked: 11 times
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publius wrote: disclord wrote: CD-4 modulated the L F-B & R F-B difference information as compressed (noise reduced) FM/PM/FM signals on a 30 kHz carrier that had unequal sidebands that extended down to 20kHz and up to 45 kHz. The baseband left and right sum signals were recorded normally except their high end was restricted to 15kHz to allow a guardband between the baseband and modulated FM carrier signal. The noise reduction used on the carrier signals was JVC's dual band ANRS (Automatic Noise Reduction System) that was somewhat like Dolby B and A-type NR. In fact, Dolby sued JVC and JVC lost and had to pay royalties to Dolby. The Neutrix I &II groove predistortion system was used in mastering the CD-4 LP to allow the Shibata stylus to track the grooves with much greater accuracy. In addition, a special vinyl was used so the carrier signal didn't get worn off the LP. Mind you, the bandwidth limitation was pretty unimportant, since it was difficult to get much response above 12 kHz on any but the best LPs, with the best playback equipment — although there were some discs pressed about the same time, using the same vinyl formulation as for CD-4 (or similar to it), which when played back with a Shibata or good elliptical stylus with a suitable cartridge would do it. But CD-4 really skated on the edge of what was technically possible with that kind of system. I am still irritated that the discrete 4-channel option on the Compact Disc was never implemented. It's in the specification, same sampling frequency & bit depth as the 2-channel option, a little more than half the running time (due to having slightly less subcode data) ; but there has never been, to my knowledge, a player built which would play a disc encoded that way, or software released to allow encoding such a disc, & my understanding is that if you generate a SPDIF stream with the 4-channel flag set, most equipment will reject it. Of course, that would also have allowed sending 4-channel audio from a MUSE decoder on one digital connexion instead of two… the total non-support of multi-channel consumer digital audio until the introduction of AC-3 & dts continues to bother me. The R-DAT spec also had a 4-channel option, as did VHD's AHD counterpart, which JVC often showed one or both of the extra channels carrying images to compliment the music. The original MCA Disco-Vision spec was 4 FM audio channels and stayed that way as late as 1977, until Philips made them drop it. Just think, we could have had 4 channel discrete audio from the beginning of LaserDisc if Philips hadn't interviened. To me, 4 channel stereo is more natural sounding than plain 2 channel stereo. And if you've ever heard the original Alan Parsons quad mix of Dark Side Of The Moon, the stereo version will become unlistenable. The SACD remix was a travesty, not to mention the horrific sound of SACD - now, the SACD recording and mastering format, SACD-Wide, is a different story. We hear in surround and our music should be presented that way too.
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laserbite34
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Post subject: Re: Quadraphonic 4 channel decoder Posted: 19 Dec 2012, 20:36 |
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Joined: 10 Oct 2006, 17:10 Posts: 3742 Location: United Kingdom Has thanked: 5 times Been thanked: 4 times
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dewdude wrote: 5.1 music might make sense; its still a gimmick. The studio albums mixed for 5.1 sound good; but I wouldn't call it natural. We evolved listening to music from a single source; usually in front of us. So when I hear an album that has a surround mix; it starts to confuse me. Now; take something like a concert where the room ambiance is mixed in surround sound and that's fine.
This is the best way I can put it; we're used to bands or orchestras being in front of us...we don't often sit in the middle.
But there is some odd reflections that one who listens might hear something pinging off a wall and moving very fast and turns to left or right rather than mild turning of the head left to right to track small changes in the front which, yes of course is where the orchestra is. What I hear or perceive say with STAR WARS end credits episode IV CLV THX editions side 3 chapter 38, time 25.07s with strings and harps and everything else thrown into this masterful Oscare winning score is I look to left or slightly more, upwards at the left-sidewall surrounds while keeping one eye on screen and my right ear still listening over to centre right and right surround even thou the surrounds are matrix mono. Then again only to right side at 25.11/12s at at 25m.14s I've got this wonderful oozing fuzzy Dolby feeling of total times infinity awe of WOOOOOOOOOOW what a Dolby mix. Lets leave it at that shall we. With the Dolby Digital AC-3 THX '97 edition same part of the score even thou its been edited a bit longer. At chapter 40, frame 30106 same kinder looking at stage left or right only its bit more up front and the surrounds and according to my Sony SDDS D3000 are down many db but not too far down in level. Centre carries a mix that is light-years apart from left and right that really sounds wonderful with bass feel and middle and high placement of instruments nicely mixed by Eric Tomlinson. And the chest bass mid pressure pressing on my chest at 30236 then slowly fading away, WOOOW WOOOW then fades in again and then CLASH the score strikes up again brassy!
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dewdude
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Post subject: Re: Quadraphonic 4 channel decoder Posted: 20 Dec 2012, 01:56 |
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Joined: 24 May 2012, 02:18 Posts: 193 Location: Manassas, VA/Northern Virginia/DC Metro/United States Has thanked: 0 time Been thanked: 2 times
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For starters....I have no clue what you're trying to describe. Did I ever pay attention to the score in Star Wars? Sure, but from a different perspective....I played upright bass in high school orchestra. Somewhere in the back of my mind; the complex bass portion of the Star Wars theme is burned in to my brain. I guess I've never really sat down and listened to it.
Now, I should probably elaborate on my "5.1 music is a gimmick"; because I have/had several dts-cd's. I was in to it for a time. Concerts always sounded great. You had the usual left/center/right mix with auidence and reflections in the rear. I actually have a Dynaco Quadaptor that I use specifically for concerts when I'm busing out the vintage Denon. However, I always found the classical recordings; even when studio-produced; tended to have a more natural flowing 5.1 mix. Dark Side of the Moon was...ok...it seemed more like an experimental concept mix..at least the original quad did. The SACD 5.1 mix sounded like someone was trying to duplicate it while giving it a move-track makeover. But, again, that album, being somewhat conceptual itself; worked as 5.1. However, I've got Steve Miller's "Fly Like An Eagle" in 5.1 and I just didn't like it. I somehow obtained an Alanis Morisette album in AC-3....and that didn't really sound good either.
I think there's one issue with this....people are used to making 5.1 mixes for movies...where you have visual cues; concerts also tend to be a no-brainer because we have something we can model them on. But studio-produced stuff...we've kind of made it up. Some of the early stereo mixes were just...horrible. Ok, they were really trying to show off the whole stereo thing...and a few technical limitations they were trying to nail down lead them to create "ping-pong" mixes; but they got better; maybe they're doing the same for studio-albums in 5.1.
I also just don't think the general public is that worried about 5.1 music because the majority of people don't sit down to listen to music the same way we sit down to watch a movie or concert. Take DVD-Audio, SACD, and Blu-Ray Audio formats in to consideration; all three of them offered not only a major increase in resolution (or an entirely different way of storing the audio as with SACD), but they also offered 5.1 options; and 99% of releases had a 5.1 mix on them. I'm of the opinion they "failed" because most people couldn't understand or hear the increase in resolution/quality and simply saw them as non-CD compatible expensive formats with 5.1 being the *only* advantage.
At the end of it all...I still see it as a gimmick that some people love; and others don't care about...and something I haven't touched in about 10 years because I've only ever owned 2.0 (unless you count the dynaco) rigs. I've got a 7.2 home theater reciever showing up supposedly on Friday...so maybe my opinions will change as I'm able to play with the format without having to burn special format audio-cd's and take them to someone who has a 5.1 rig. Although I'll be 5.0 at the most since I don't own a subwoofer and with my speakers; haven't needed one.
Laserdiscs in ProLogic II(whateverrevision) might be interesting.
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