Detroit - late 1960's early 1970's - Two FM Radio station simulcasted music.

[beachboy]

"In the early 1970s, radio stations WDET-FM [[Wayne State University) and WABX-FM [[then the progressive underground station in Detroit) did a several hour long discrete Quadraphonic simulcast, ... Everyone who listened came away enthusiastic and impressed."

http://www.wguc.org/content/display.asp?id=26

Hey Dan Wesson, that page brings back memories, eh? Quad was a great innovation and a realistic "first step" in surround sound [[SS) ... we heard the simulcasts [["In Concert" on WRIF and WXYZ-TV referred to by Meddle) as far away as the Thumb [[with a 90 ft tall mast-mounted antenna having FM, VHF, and UHF amplifiers, no less!) "Receivers" cobbled together from old amps. Fun!

Some FM stations attempted to encode quad in two channels for stereo broadcast with a decoder at the receiver. Results: predictable reconstruction losses due to nonuniqueness of the matrix products, multipath distortion and transmission noise. It's fun to note that early experiments in "stereo quadraphonic" FM attempted to use the SQ format described here:

http://en.wikipedia.org/wiki/Stereo_Quadraphonic

until superseded by the Quadraplex technique [[1970s):

http://en.wikipedia.org/wiki/FM_broa...uadraphonic_FM

which did not work so well for long transmission paths. <sigh>

Despite all these good intentions, quad and the simpler surround sound protocols [[e.g., 5.2, 7.1 and 7.2, among others) have inherent "fill" and "directionality" problems, regardless of the delivery medium. Details are discussed in an accessible way in this series of web pages by Wendy Carlos [[a pioneer of electronic music - think: score for Clockwork Orange and Tron, among others):

http://www.wendycarlos.com/gosurround.html .

As noted in the link you cited [[http://www.wguc.org/content/display.asp?id=26), SACD and Audio-DVD are promising advances. Perhaps they will eventually be extended to consumer-recordable BluRay media so we can realize higher values of T and B in the T.B SS reconstruction. Who knows, we might even approach the "infinite baffle", as we used to call it in the 1960s. [[just kidding...)

Currently upgrading my home 13.4 SS system to synthesize non-encoded intermediate channels using programmable DSPs. Eventually we want to build a 30.8 system [[center, left and right front-center, left and right front-corner, left and right [[side and rear), rear center, top and bottom center; incl. subwoofers in listening room corners) for reproducing pipe organ and symphonic performances. Crazy? Yes, but "organ fanatics" are a tad different ...