Soviet Quadraphonic Research
Don't know how useful this will be on here, but I figure it's worth posting for posterity's sake. I've had to remove most of the links to get it past the filter so please forgive.
In the late 1970s, a research team started by Yuriy Berendyukov under the supervision of Yuriy Kovalgin at the Leningrad Electro-Technical Institute of Communications (now Bonch-Bruevich Saint Petersburg State University of Telecommunications) investigated the psychoacoustical shortcomings of Western quadraphonic formats such as SQ, QS, and CD-4. Much like Wendy Carlos (Wendy Carlos' Quadraphonic Folly) and Michael Gerzon (Surround-sound psychoacoustics, Wireless World, Dec. 1974) the Soviets found the typical four-corner square layout yielded poor phantom imaging and localization.
After many statistical psychoacoustic tests, Berendyukov found that the best four-speaker layout for accurately locating phantom images was a trapezoid, with the listener situated near the bottom baseline. Eventually, a simple polarity-based encoding/decoding matrix was developed, and the system was dubbed ABC in reference to the three phantom zones the system tries to retain. The system's stated goal was to reproduce a 360-degree panorama, such as the full ambience of a concert hall.
Eventually, a demonstration record was pressed in 1978 along with a full album in 1980 with Berendyukov's country-folk band. In 1982, an op amp decoder along with a general overview of the system was published in the Soviet DIY electronics magazine Radio (#9, 1982).
As it stands, I've been in contact with Berendyukov for the last few months and he's graciously allowed his dissertation abstract to be made public. It can be found here. Unfortunately, the full dissertation is lost to time and even Berendyukov himself no longer owns a copy. On the plus side, a book worth checking out is Kovalgin's Акустические основы стереофонии (Acoustic Foundations of Stereophony (1978)) which not only touches on Blauert-level stuff but also has a small chapter on Berendyukov's initial SQ/QS testing.
Both men are still alive and agreed to meet up and reminisce toward the end of the summer. If anything archivable is shared, I'll be glad to post some links.