4 channel newbie

[SPXER]

Sansui Vario Matrix for QS and Fosgate for SQ surround in vintage tronics is as good as it gets also for stereo to surround, my main interest. There is also the Space and Image Composer a delight. If you want something new look to the Involve Surround Master. It does QS and SQ but alas not the same wrap around performance of the older units. There are good ways around that.

I am puzzled by what you say here, Sonik.
Doesn't the placement of the speakers determine the "wrap around"?
And also, if the Involve SM is a modern recreation of Sansui Vario-matrix, why does it not perform as well? Thanks for helping me get a grasp of all this new-to-me info.

 

[furui_suterioo]

I am puzzled by what you say here, Sonik.
Doesn't the placement of the speakers determine the "wrap around"?
And also, if the Involve SM is a modern recreation of Sansui Vario-matrix, why does it not perform as well? Thanks for helping me get a grasp of all this new-to-me info.

The Involve SM natively uses straight QS mode(with high seperation just like Variomatrix), a hard panned sound from a stereo source will emanate from between front and rear of the given set of side speakers.
Sansui decoders have additional QS-Synthesizer Surround mode that Involve doesn't have which would move that same sound completely to the given rear speaker, giving more dramatic results than regular QS mode (which is also similar to DPL2 but faster and more seperation).
The Involve decoder can be made to recreate Sansui style Synthesizer mode with some external signal modification, as Sonik has done.
Otherwise the Involve is essentially the same as a Sansui decoder in QS mode.(many people say it's better)
I use a Sansui decoder in my home system and Involve in the car, they are both great.

 

[Sonik Wiz]

I am puzzled by what you say here, Sonik.
Doesn't the placement of the speakers determine the "wrap around"?
And also, if the Involve SM is a modern recreation of Sansui Vario-matrix, why does it not perform as well? Thanks for helping me get a grasp of all this new-to-me info.

Well said @furui_suterioo . To elaborate a little, Sansui had two modes dedicated to stereo playback the Hall mode and Surround mode. The latter gives the wrap around effect. All it takes is a little opposite phase blending between the stereo chs before decoding. Proper speaker set up only presents what the decoder is doing, but what I'm talking about actually changing the decoded output.

The Hall function puts 100% un-decoded stereo on the front chs. Then a little in phase cross blending is added before decoding and the result ends up in only the rear chs.

These should be considered add on features, not part of the basic QS decoding. Involve chose not to use them as they thought two more front panel choices would be too many and confuse folks. Their call. Heavens knows I've never passed up a chance to tell 'em it should be included. It's their company not mine & they certainly gave a bonus reward by adding in SQ decoding based on forum comments.

Doing that opposite phase blending is pretty simple in hardware if you're DIY electronics kind of guy. It's also easy to do on a PC using just about any audio editor.

Let me know if I can baffle you any further...

Hello @chucky3042

 

[par4ken]

I read the "History of Surround Sound Processing: The Battle for Dolby Pro Logic II".
So do I understsnd that DPL2 is the good stereo to quad synthesizer?
If so wouldn't a receiver with DPL2 be acceptable?

I have NEVER heard any form of Dolby decoding that sounded any good on music. I suspect that is why most people use their surround systems for movies while listening to stereo for music.

Vintage quad decoders or the Surround Master do a much better job.

 

[MidiMagic]

I am puzzled by what you say here, Sonik.
Doesn't the placement of the speakers determine the "wrap around"?
And also, if the Involve SM is a modern recreation of Sansui Vario-matrix, why does it not perform as well? Thanks for helping me get a grasp of all this new-to-me info.

The more discreteness, the less wrap-around.

 

[par4ken]

The Hall function puts 100% un-decoded stereo on the front chs. Then a little in phase cross blending is added before decoding and the result ends up in only the rear chs.

I was surprised that Sansui left the front channels undecoded in the Hall mode. Sonic your original Pre-synth circuit being fully adjustable was able to apply in phase or out of phase blend to the QS decoder making Hall/QS/Surround switching unnecessary. In phase produces the Hall effect by focusing more sound to the front. In doing so some out of phase ambiance is also removed. Hall effect as implemented by Sansui is only half decoded!

I think that we both agree that adding a bit of out of phase blending to produce the Surround mode is usually the best option for stereo enhancement. To explain to the uninitiated, as we add out of phase blend the QS decoder will move hard panned left and right signals toward the rear speakers. With mixes that include intermediately panned signals they will also be pulled apart moved more toward the left and right front speakers. Those lackluster stereo mixes are pulled apart to sound like real stereo across the front instead of near mono, while some bits pop up from behind.

The only drawback of adding in phase blending is that the center is reduced in level as well. Inpractice as long as we are careful not to over do the blend we are OK.

 

[Sonik Wiz]

The only drawback of adding in phase blending is that the center is reduced in level as well. Inpractice as long as we are careful not to over do the blend we are OK.

Me thinks you mean opposite phase blending? Yes I do read your posts closely...
In the maybe 3 Sansui units I actually tested the opposite phase blending was less than what might be found in Sansui patents or tech articles. Closer to -10dB to avoid over doing it with whatever out of phase stuff might exist in the original recording.

Remember that parable of 10 blind men describing an elephant? That's a bit what I see here, you, me, & fururi explaining the Sansui Surround Synth function to @SPXER . I'll try another way.

If a sound being lead guitar or test tone is dynamically panned from left to right in stereo then in basic QS or like in the Involve decoder, sound moves from center left>center front>center right. With Sansui Surround Synth (or accomplished other ways) the sound starts in Left back> center left >left front> center front > right front> center right > right back. It makes a nice clock wise sweep about the listening area.

With real music it becomes more vibrant and bouncy, more like a real quad recording. Dolby PL II does not do this nor the Involve SM. The Space & image Composer & Fosgate 101A with Tate DES also does this but the circutry to do this for an SQ decoder is more complex. The S&IC unit was nice because it offered adjustable control over this function.

 

[furui_suterioo]

I don't mean to make things more confusing but I see that some Sansuis like the QRX-5500 have two Hall and Surround modes, are they all varying degrees of pre synth blending?

 

[Sonik Wiz]

I don't mean to make things more confusing but I see that some Sansuis like the QRX-5500 have two Hall and Surround modes, are they all varying degrees of pre synth blending?
View attachment 95213

That is really quite amazing. I've never seen that before.

 

[par4ken]

I don't mean to make things more confusing but I see that some Sansuis like the QRX-5500 have two Hall and Surround modes, are they all varying degrees of pre synth blending?
View attachment 95213

I looked into this before but forget the exact details. I once assumed that the switch might bypass the allpass phase filters in the synthesizer mode, but it does not. I suspect that Synthesizer Surround and Hall function the same to that of other units. My QA-7000 Amplifier has the same switching configuration. According to this QS surround is normal (square four corner) QS, not sure if they still bypass the fronts in QS Hall mode? Information here.

 

[jaybird100]

I have NEVER heard any form of Dolby decoding that sounded any good on music. I suspect that is why most people use their surround systems for movies while listening to stereo for music.

Vintage quad decoders or the Surround Master do a much better job.

The Surround Master does a better job with actual Dolby Surround-encoded music than any any PL II system I've heard, too.

 

[Sonik Wiz]

The Surround Master does a better job with actual Dolby Surround-encoded music than any any PL II system I've heard, too.

I must agree!

 

[SPXER]

Aside from the QRX ?001 series receivers, do any Sansui quad amps or processors etc. have the Vario-matrix decoders?

 

[jaybird100]

Aside from the QRX ?001 series receivers, do any Sansui quad amps or processors etc. have the Vario-matrix decoders?

All QRX receivers have Vario-Matrix, although the X001 series models, such as the 7001, have more advanced versions. the 9001 has the best version of Vario-Matrix.

 

[furui_suterioo]

Aside from the QRX ?001 series receivers, do any Sansui quad amps or processors etc. have the Vario-matrix decoders?

Also the QSD-1, QSD-2, and QSD-1000. The D-2 is the same decoder as QRX receivers. The D-1 is tri-band and the D-1000 is single band but newer design(the rarest of them). There are also a couple of prototypes but I don't recall the model numbers.

 

[jaybird100]

The Involve SM natively uses straight QS mode(with high seperation just like Variomatrix), a hard panned sound from a stereo source will emanate from between front and rear of the given set of side speakers.
Sansui decoders have additional QS-Synthesizer Surround mode that Involve doesn't have which would move that same sound completely to the given rear speaker, giving more dramatic results than regular QS mode (which is also similar to DPL2 but faster and more seperation).
The Involve decoder can be made to recreate Sansui style Synthesizer mode with some external signal modification, as Sonik has done.
Otherwise the Involve is essentially the same as a Sansui decoder in QS mode.(many people say it's better)
I use a Sansui decoder in my home system and Involve in the car, they are both great.

And, like the QSD-1, the Surround Master is a tri-band decoder. I'm not sure if any decoder before it employed tri-band for SQ as well, that actually made it into consumers' hands. Also, unlike most Tate System SQ decoders, there are no "pumping" effects with the SM.

 

[par4ken]

Also, unlike most Tate System SQ decoders, there are no "pumping" effects with the SM.

There is no pumping with the S&IC! Even anomalies from the unit with the older National chips are eliminated by backing off the Separation control a bit. With the unit that uses the Exar chips anomalies are confined to the back channels and are only really audible when listening to them in isolation. I would not call it pumping. Pumping is only an issue with logic type SQ decoders, when adjusted properly pumping is not noticable.

 

[jaybird100]

There is no pumping with the S&IC! Even anomalies from the unit with the older National chips are eliminated by backing off the Separation control a bit. With the unit that uses the Exar chips anomalies are confined to the back channels and are only really audible when listening to them in isolation. I would not call it pumping. Pumping is only an issue with logic type SQ decoders, when adjusted properly pumping is not noticable.

The pumping effect has been discussed in these forums before. Let's just say the SM does at least as well as the Tate, for a lot less money, plus is also does QS. The Tate doesn't do that.

 

[par4ken]

The pumping effect has been discussed in these forums before. Let's just say the SM does at least as well as the Tate, for a lot less money, plus is also does QS. The Tate doesn't do that.

Actually you can decode QS with the Composer. You use the Stereo Enhance mode and set the stereo enhance control midway. Everything with the exception of full centre (which skews to the right back) decodes properly. Only in recent times (20 years maybe) did I own a real QS decoder. Prior to that everything went through the Composer!

 

[Sonik Wiz]

Interesting direction this discussion is taking. But I think it will do nothing to help out @SPXER .