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Anyone remember "Quadraphonic Sound"?...Makes me laugh when I think about it..
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Did anybody here ever try the Hafler rear speaker wiring technique?
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Yeah, but it produced crazy results depending on the material you played. It simply dropped the difference signal across a rear (or rears) speaker strapped across the two positive terminals of the stereo mains. Sometimes the output would be too loud and sometimes you'd hear nothing. I remember Dynaco actually produced a device they called a quadaptor that used the hafler principle, but provided some control. I built one of these and used it for a while. Worked well enough I guess.
I was working part time in the late 60's to support myself through college repairing stereo equipment at a local HiFi repair shop. I remember several receivers started showing up that supported the new 'Quadraphonic' sound. To test these units out I purchased a few quadraphonic records - there weren't many. I do recall the first time I set four speakers (RF, LF, RR, LR) around my workbench and tested a quadraphonics decoder. Amazing, I could actually hear something different coming from the rear speakers. I remember thinking that this idea had possibilities (read ProLogic) and actually ended up building a four channel integrated amp from scratch (including a phono preamp) and used the guts of a Heathkit quadraphonic decoder in it - duh. I used that thing for years.
Four channel quadraphonic matrixing was an encoding process where four audio signals were mixed down to two and cut on a record. When the resulting two channels were played back from the record through a decoding process that had the same algorithm as the encoding processor, the original four channels were effectively retrieved (again, read shades of future ProLogic encoding - no one thought to combine it with video at the time).
Like all failed experiments, it seems if there are several standards available on the market, then they are doomed. (Geez, will the electronics industry ever learn to stop shooting itself in the foot).
There were three quad matrix encoding schemes used with records and appropriate decoders produced in those formats. Columbia (SQ sheme), Sansui (QS scheme), and ElectroVoice (Universal sheme).
There were receivers sold that decoded one or more of these schemes. Standalone decoders were also sold that could be used to create a four channel system from a stereo system. Just like any decoder, they had two RCA inputs that were fed from the preamps Left and Right outputs. Then it has four RCA outputs that you fed four power amps. The outputs would be Left front, Right front, Left rear, Right rear.
Usually they had a selector dial on the front that would select between (1) Pass through of Left and Right channels unaltered (2) Some goofy synthesized matrix scheme (3) Matrix decoding of either QS, SQ, or Universal schemes.
To take advantage of the matrix decoding you needed an appropriately encoded record using the same scheme.
The synthesized matrixing schemes were used when you played a record with two normal stereo channels and you wanted synthesized four channel sound (albeit ******). The synthesized decoding simply manipulated the phase relationships between the two stereo channels to create the four outputs. It basically sounded like a bad DSP.
Anyway, this 4 channel matrixed system died from lack of interest and was replaced not too many years later with a 5 channel matrixed system called ProLogic.......and so on....................................
brucek
02-18-07, 04:42 PM
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now 5.1 (or up to 7.1 if there was any content) linear PCM, DD+, dts-HD HR or lossless Dolby TrueHD, dts-HD MA at up to 24bit/96kHz all on either Blu-ray or HD DVD format shiny discs. I have two primary music HD DVDs, "The Way Up - Live" by Pat Metheny Group and "Live at the Greek Theatre" by Chicago/Earth Wind & Fire. Both in 5.1 new audio codecs but still lossy 
. At least DD+ is often 1.5 Mbps rather then the old 640 kbps max of legacy DD. The Pat Metheny title does have 2 channel lossless linear PCM though. Reports are that Lord of the Rings will come out in 7.1 surround sound. The player manufacturers need to update their designs to handle the new 7.1 titles.
