First, the Tate Directional Enhancement System is not a decoding system, it is an Enhancement system that requires a matrix decoder for a front end. While it is theoretically possible (Dolby actually did it) to feed the DES a signal from a non-SQ matrix, Tate was an SQ licensee and optimized performance using SQ as the model.quadralizer said:Hi Steve,
Fascinating article so far, great to see all this in depth detailed info straight from the source.
I have always understood that Dolby Labs™ originally used QS as the basis for Dolby Stereo™, (which no doubt accounts for the film soundtrack of Tommy sounding like the tape machine was out of phase when listened to un-decoded in stereo).
Therefore if Dolby™ became a Licensee and swapped over to using Tate Chips in their Professional Cinema Products (remember little or no domestic Dolby™ Product, apart from Dolby 'B'™ NR of course, was around in those days.)
Does this mean the Dolby Surround™ encoding was changed to SQ? (which I think I remember reading something about on the Dolby™ Website) or are the Tate Chips capable of decoding other matrix's as well as SQ?
And thereafter as DPLII™ was (if I am correct say) developed by Jim Fosgate for Dolby™ Labs to Decode Dolby Surround™ Encoded material, does it not follow that when reproducing 'Matrix Quad' Material with DPLII then it would be SQ NOT QS that is correctly decoded as which seems to be the common opinion on this board.
Short of asking Ray Dolby(™?) himself, you sound like the guy to sort out this confusion once & for all. OR is my 'Logic' just a load of 'Reverse Polish'?
Also you mentioned that Tate hand built Directional Decoders from discreet components. Where any cct's ever published of this or similar discreet enhanced decoding schemes? Would be great to build one as a bolt-on to a Sansui QRX, all we need is the Schematics!
John - Liverpool UK
Because the Tate chips themselves don't decode anything, they were applied to the Dolby system in such a way that they improved what they already had going. In other words, a flavor of QS was the basis for the original Dolby Surround and the Tate System was used to create a new system better than and compatible to the original Dolby Surround. How much QS survived the transition is anyone's guess. You would have to ask someone at Dolby!
A Tate system built from discrete components would be huge, expensive and impossible to keep tuned. This is why it was reduced to IC form. Martin Willcocks (the Engineer who designed the Tate DES) had a magazine article in the works that would have allowed you to buy a Tate chipset and with a small PC board, make a DES that you could plug into your existing matrix decoder (I think I still have a copy of the article and PC layout somewhere). However, when the chips came out of fab at National Semiconductor and it became apparent that they did not work correctly, the article was shelved.