MISC: Sansui QSD-4 QS Decoder

[JonUrban]

Please post comments and and photos of this quadraphonic decoder in this thread.
We'd love to hear from those who own or have owned this device.

SANSUI QSD-4

Rarity: ULTRA RARE

Average Sale Price: $1K-up

 

[8trackman]

wow this thing is cool- what are the things that pull off?- or rather what does this thing do? only decodes QS records?

 

[TimK]

Looks like the first version of HAL. Memory modules on the right.

 

[The Quadfather]

I imagine the "things that pull off" are the decoder cards. The idea was that when new technology came along, upgrades could be produced. Of course, they never were. I recall that other models and makes of decoders had plug in cards, for this reason. Except for Marantz (modules), I don't recall the improvement cards ever being produced. This is the first one I have seen with the cards acessable from the front. I like the meters.

The Quadfather

 

[8trackman]

cool, so hows does with thing compare to QS-D1000? I am guessing this was made afterwards as this seems sort of 1980s futuristic? I am guessing HAL refers to an early 1980's computer system?

 

[Q-Eight]

I am guessing HAL refers to an early 1980's computer system?

No, 2001: A Space Odessy 1969 Stanley Kubrick film.

 

[mtgc]

H + 1 = I
A + 1 = B
L + 1 + M

Of course all concerned with this film firmly deny any connection.

MTGC
Michael

 

[The Quadfather]

Incidently, regarding those Marantz receivers with the SQ modules, It was rumored that Audionics intended to make a Tate module for the Marantz receiver. However, sadly for Marantz owners, it never materialized. That would have made Marantz receivers, which were very fine receivers, the SQ equivalent of the Sansui Variomatrix series, which were also very fine receivers.

The Quadfather

 

[Quadrockasaurus]

QSD-4 decoder/QSE -4 encoder ad....

 

[Disclord]

The QSD-4 is a single-band Vario-Matrix decoder for QS. It's a pro model and has better quality circuitry than the consumer models. The QSD-1 is a better decoder though due to its ability to decode in 3 bands, unlike any other Vario-Matrix decoder, including the vaunted QSD-1000.

The QSD-4 was used in the BBC's large-scale tests of the various matrix quad systems (For SQ, the awful CBS Labs Model 2400 Full-Logic decoder was used) because the BBC wanted only the most advanced professional gear, which at the time, the QSD-4 was. For decoding QS, while it was better than SQ's logic decoder, the BBC still didn't like it too much but modified it to decode Matrix H, then the BBC used the Vario-Matrix chips to create a truly custom and more advanced Matrix H decoder. The QSD-4's big failing in the BBC tests was the side-to-side shifting of instruments and the soundstage due to QS requiring side-to-side enhancement.

 

[surround.sound.enthusiast]

Both Quadfather and Disclord hit it right on the head about this unit, especially Disclord with BBC background I didn't know.
Here are some additional close-up photos, note the Sansui memo in the last photo.