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Topic: Anyone thought of quadraphonic sound?
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Claus Harding
Phenomenal Film Handler
Posts: 1149
From: Washington DC
Registered: Oct 2006
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posted 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.
--------------------
"Why are there shots of deserts in a scene that's supposed to take place in Belgium during the winter?" (Review of 'Battle of the Bulge'.)
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Joseph Banfield
Film Handler
Posts: 93
From: FRANCE
Registered: Jun 2010
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posted 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]](biggrin.gif)
[ June 23, 2010, 07:27 PM: Message edited by: Joseph Banfield ]
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Bill Brandenstein
Phenomenal Film Handler
Posts: 1632
From: California
Registered: Aug 2007
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posted 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!
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