8mm Forum: Anyone thought of quadraphonic sound?

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Posted by Joseph Banfield (Member # 2082) on June 23, 2010, 03:34 AM:

I am new here on the board and was just wondering if anyone had experimented with using quadraphonic sound from a stereo projector? Since quadraphonic SQ is a matrixed format put down on a standard stereo track it would seem possible that it would also work on stereo film, which has two seperate channels. The only external piece of equipment required would be a quadraphonic receiver from the 1970's to use as the amplifier. The beauty of using a system like this would be that the sound recorded plays back perfectly in normal stereo but when ouputed to a quad receiver it detects the rear channels and sends them to the rear speakers. Although a quad matrix recording is not truly discreet as there is some bleedover in the front channels, it does work quite well and the sound can travel around the four speakers nicely. I myself do not have a stereo projector but it seems interesting and something I myself would do if I did. I make SQ quad recordings all the time from DTS sound sources mixed down into 4 channels and pop them into Adobe Audition and run a SQ script which does all the work for me...after finished I have a matrixed SQ quad recording in a standard stereo recording that plays back in either standar stereo or quad just like it was done on records in the old days. I thought this might interest some of you out there.

Posted by Claus Harding (Member # 702) on June 23, 2010, 08:28 AM:

Joseph, welcome,

Very interesting. I recall the "battle" in the 70es, with the incompatible LP formats, but with Dolby Surround, it's as if the ol' 4-channel never really died.

But, specifically to Quad: if I remember right, wasn't the steering logic frequency-dependent? (high pilot tones, which wore off the LPs, were the thing that helped steer the sounds?)
I don't know if this would have an impact on the Matrix model, but I am asking out of curiosity as you obviously have it working when you extract from DTS sound.

Since the film projectors have limited frequency response, would this have an impact on the accuracy, or is this not applicable to the Matrix system?

Claus.

Posted by Gary Crawford (Member # 67) on June 23, 2010, 09:01 AM:

I think Claus may be right . However..I've heard that with some films...with good balance stripes and good well adjusted projectors ( no social problems) that people have been able to extract the old Dolby surround ...with the right dolby equipped amp. Never really went to the trouble since so many of my films , up until lately, have been from the 20's through the 1950's.

Posted by Michael Beyer (Member # 1143) on June 23, 2010, 10:30 AM:

I have an Shure HTS-5000 (Home Theatre System) from the 70's which generates from mixed-down-Stereo to a nearly 5.1-Sound.
You need this system and 3 amps.

Posted by Joseph Banfield (Member # 2082) on June 23, 2010, 03:28 PM:

No, you guys got the wrong system...there were actually 3 quad systems in use during the 70's. You guys are thinking of that terrible CD-4 quad format from JVC where the vinyl disc wore out after just a few plays and contained a high frequency carrier signal (which is why the disc wore out so quickly in the first place). That CD-4 vinyl system had to be played back using special cartridges, whereas the SQ and QS system used standard stereo cartridges. The most successful by far was the Columbia SQ system. This is the matrix system that is recorded onto a standard stereo two channel sound track. The two rear channels are mixed -45 and +45 degrees out of phase to the front channels. It is the quad receiver that detects this phase difference in the recording and uses logic circuits to decode the back two channels during playback and steers them where they need to go in the four speaker system...it is totally ingenious! The SQ system of quad is fully compatible with standard stereo playback. In other words, if you have an SQ encoded stereo source and play it back on a standard stereo that is just what you get...standard stereo with no loss of information at all. The sums from the front and back just add up back into two channel stereo sound like it is not even there, but when played back using a quad SQ decoder...VIOLA four channels of sound!

SQ quad matrix can be recorded onto CD, magnetic tape or whatever format is current. In fact Dolby bought the rights to this SQ system from Columbia after the quadraphonic disaster of the 70's and used this matrix system on film soundtracks with minor changes to the original Columbia SQ system.

I create audio CD's all the time from new DTS sources and rip the individual mono tracks from the DTS source and convert them into an SQ two channel stereo file and burn them to a standard audio CD, which works on all stereo receivers as well as quad receivers with an SQ decoder. And just like Columbia originally intended the system is totally compatible with existing two channel stereo receivers. Imagine four channels from only two, and it is so easy to do! [Big Grin]

[ June 23, 2010, 07:27 PM: Message edited by: Joseph Banfield ]

Posted by Joe Taffis (Member # 4) on June 23, 2010, 04:27 PM:

Hello, i'm not into the technology like you guys, but I had an RCA Quad 8-Track system (4 speakers) in my 1973 Mustang, and the sound and four speaker separation was awesome! I heard things (vocals and instruments) on albums like "Best of the Doors", "Jim Croce's Greatest Hits", and similar lps that I NEVER heard on the regular vinyls or 8-Track tapes in release at the time. As a musician, it blew me away! [Smile]

Posted by Bill Brandenstein (Member # 892) on June 23, 2010, 07:24 PM:

Joe, that blew you away because each speaker was supplied with its own track on the tape. Those tape cartridges were discrete Quad and probably were the best way to go! CD4, SQ, or QS all require the 4 channels to be encoded to 2, then pulled back apart by a decoder. Personally, I think it is a very inferior technology and leaves a lot to be desired particularly because the separation is quite weak. Joseph, if you're taking DTS sound sources and encoding/playing them back as SQ, you should be well aware of the huge hit in detail and separation inherent with that process. Now, I'm afraid you won't find much enthusiasm here for your Quad-on-Super 8 efforts (besides the fact that it's complicated!) because there's no center channel to go with the screen, and literally everything on film is mixed with a center channel in mind. Further, no matrix surround has ever worked better than the Dolby Pro Logic II that's available these days. Many of the stereo Super 8 releases are presented by your fellow enthusiasts on Pro Logic systems, and when the film is recorded well can sound really great. Another approach is to sync stereo or surround sound to Super 8 via a double-system sound method. This gets a bit technical, but doesn't have to be expensive if you have access to an Elmo or Bauer projector that will accept an external sync signal. See all the way at the bottom of this page for my comments there. It's fussy to do but I have on rare occasions run 5.1 sound to Super 8 that way. We should be envious of our European friends who can take a 25fps DVD and a simple Pedro box and easily run the 5.1 DVD sound with a Super 8 print! Not so easy here in NTSC land!

Posted by Joseph Banfield (Member # 2082) on June 24, 2010, 03:21 AM:

Bill, of course, what you say is true but if you can squeeze one more ounce of magic out of a hobby then why not do it if you have the technology to do it.

Of course I know that ripping from DTS and downmixing to SQ quad looses some detail when compared to the original DTS file. But if you have a quad amp you need material to show off your amp and this is why I do it.

For good seperation though you do need a late model quad amplifier where the seperation is much better than the earlier ones because they used full logic chips in the last days but it was already too late because the consumer was fed up. And if you are lucky enough to have a Tate decoder then you can achieve almost discrete sound but they cost big dollars on Ebay when they show up. I have also been told that Dolby Pro Logic II decoders work like a charm as well with an SQ source, but have not tried that myself.

But it is like Bill said, rather complicated to do for the average person but still feasible. I was just wondering if anyone had ever tried something like this for their films.

Posted by Bill Brandenstein (Member # 892) on June 25, 2010, 01:19 AM:

The main thing is that it provides you enjoyment and a means to be creative. So carry on, even if you're a contingent of one! But who knows? Maybe someone else will happen upon this who does Quad as well as Super 8.

Posted by Barrie Didham (Member # 1741) on June 25, 2010, 01:52 AM:

I like quad myself and remember afew dvd,s came out with SQ and QS sound.
With some work i quess you could add quad to a two track super 8 film.
One of these would help since you can sync it

Posted by Joe McAllister (Member # 825) on June 26, 2010, 04:43 PM:

This thread has reminded me that I have often wondered if a pseudo stereo system from the 50's called Perspecta sound could be adapted for home use.
This used a mono optical track with sub sonic frequencies that prompted the amplifier to pan the sound to different speakers simulating stereo. The idea was that these prints could be shown either in cinemas with standard equipment or those that could decode the "stereo" information.
"Invasion of the Body Snatchers" and "To Catch a Thief" were issued in this format.

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