SQ - Front Back Logic Decoders

[kfbkfb]

I don't recall much discussion here about SQ decoders
with just Front Back Logic (according to a Sony ad in
a 1972 special Quad magazine, the Sony SQD-1000
has only Front Back Logic that enhanced separation
by up to 6dB - giving 9dB total F/B separation?).

I generally prefer minimizing signal processing (I set
the Tone Controls to Flat and I don't use any of the
Surround Sound Enhancement modes on my Receiver)
so limiting SQ logic processing to Front Back only
(perhaps with the passive 10/10 blend) appeals to me.

Has anyone done any listening tests with a SQD-1000
and a Tate (for example) to see how well Front Back
Logic does in comparison?

Kirk Bayne

 

[Doug G.]

I misssed this.

I don't have an SQD-1000 but I do have an SQD-2050 and its specs. are 20dB separation RF-LF, 14dB separation RB-LB, and 10dB separation center front-center back so it's obvious it has only front-back logic but no wave matching like the later Sony decoders (SQD-2020 etc.).

However, I still like the sound of it (I actually have 2) and those separation specs. are good enough for a good quad effect.

I have never heard a Tate so I can't comment on any comparisons with that.

Doug

 

[Disclord]

SQ without any logic processing sounds just like double stereo - its a system that MUST have some sort of logic processing to produce the correct quad effects. The front back logic ONLY enhances Center Front and Center Back - the Corners still have 2.9db of separation and you can often hear the logic move the CF to CB depending on the recording. Plus, F/B decoders often used the 40% blend on the rear channels which produces only 8db of Lb-Rb separation. F/B logic decoding is awful - that's why it was abandoned for more advanced methods.