This was a prototype from the BBC that was never released to the public! Paging Oxford Dickie!
http://www.ebay.com/itm/Rare-BBC-Ma...uadraphonic-Decoder-QS-RM-QSD-2-/111122985730
"OFFERED is a quadraphonic matrix decoder working to Sansui's Variomatrix principle based on the QSD-2 in very good condition, just out of storage. This version is extremely rare possibly unique in view of its modification by Sansui engineers; the modified decoder is an engineering development sample never brought to market.
This museum piece may be the only variable-matrix HJ decoder in existence, having been modified by Sansui engineers for use as an experimental HJ-matrix decoder for evaluation tests. Matrix HJ, which had strong similarities with Sansui's QS Regular Matrix, was a compromise between the BBC's H-matrix and the J-matrix of the NRDC-backed Gerzon/Fellgett proposals. At the time, Sansui were in discussion with the BBC about the possibility of standardising surround-sound matrix parameters for broadcast use.
Following the BBC's decision against a quad broadcasting standard, I bought this experimental version of Sansui's decoder on the closure of their London office."
http://www.ebay.com/itm/Rare-BBC-Ma...uadraphonic-Decoder-QS-RM-QSD-2-/111122985730
"OFFERED is a quadraphonic matrix decoder working to Sansui's Variomatrix principle based on the QSD-2 in very good condition, just out of storage. This version is extremely rare possibly unique in view of its modification by Sansui engineers; the modified decoder is an engineering development sample never brought to market.
This museum piece may be the only variable-matrix HJ decoder in existence, having been modified by Sansui engineers for use as an experimental HJ-matrix decoder for evaluation tests. Matrix HJ, which had strong similarities with Sansui's QS Regular Matrix, was a compromise between the BBC's H-matrix and the J-matrix of the NRDC-backed Gerzon/Fellgett proposals. At the time, Sansui were in discussion with the BBC about the possibility of standardising surround-sound matrix parameters for broadcast use.
Following the BBC's decision against a quad broadcasting standard, I bought this experimental version of Sansui's decoder on the closure of their London office."