A place for interesting quad encode/ decode tech articles

[chucky3042]

Dear All

I have a ton of background research stuff I read before going nuts to design Involve encode/ decode. Here is one I unearthed from my home desk a few days ago.

I thought this could be a good place to put other similar research/ discussion articles to improve our general pool of knowledge

Enjoy the read, I will ask questions and mark you later.


https://cdn2.imagearchive.com/quadraphonicquad/data/attach/61/61727-Vario-MatrixScan-210420-0003.pdf

 

[kfbkfb]

https://www.worldradiohistory.com/A...0s/1975/Radio-Electronics-1975-10.pdf#page=16

A 4-3-4 implementation of QS is briefly mentioned in FIG. 8 (b).


Kirk Bayne

 

[chucky3042]

I will dig up a bunch of articles Disclord (RIP) sent to me years ago........

 

[mandrix]

Dear All

I have a ton of background research stuff I read before going nuts to design Involve encode/ decode. Here is one I unearthed from my home desk a few days ago.

I thought this could be a good place to put other similar research/ discussion articles to improve our general pool of knowledge

Enjoy the read, I will ask questions and mark you later.


https://cdn2.imagearchive.com/quadraphonicquad/data/attach/61/61727-Vario-MatrixScan-210420-0003.pdf

You may go ahead and mark me "failed". lol. I haven't owned a Sansui in 50 years or the other QS capable brands.
But is interesting and a good reference!

 

[par4ken]

https://www.worldradiohistory.com/A...0s/1975/Radio-Electronics-1975-10.pdf#page=16

A 4-3-4 implementation of QS is briefly mentioned in FIG. 8 (b).


Kirk Bayne

There are many errors in that article. I posted about it before. When I first read the article I didn't understand it, that was because the author didn't know what he was talking about! They couldn't even copy the CBS schematic correctly!

What it does is act as an SQ encoder (forward oriented) placing sounds panned hard L and R into the rear (centre remains upfront). It turns stereo into SQ which can then be decoded.

 

[par4ken]

Dear All

I have a ton of background research stuff I read before going nuts to design Involve encode/ decode. Here is one I unearthed from my home desk a few days ago.

I thought this could be a good place to put other similar research/ discussion articles to improve our general pool of knowledge

Enjoy the read, I will ask questions and mark you later.


https://cdn2.imagearchive.com/quadraphonicquad/data/attach/61/61727-Vario-MatrixScan-210420-0003.pdf

That was thanks to our very own Sonik Wiz published years ago in the MCS Review.

 

[par4ken]

https://www.worldradiohistory.com/A...0s/1975/Radio-Electronics-1975-10.pdf#page=16

A 4-3-4 implementation of QS is briefly mentioned in FIG. 8 (b).


Kirk Bayne

What does QS have to do with it? The article is about SQ, reading the entire article the author has confused the two. That is (fig. 8) the weirdest speaker arrangement I've ever seen. It must have been devised by Bose (direct/reflecting). It would be better to toe them outwards.

 

[Sonik Wiz]

Dear All

I have a ton of background research stuff I read before going nuts to design Involve encode/ decode. Here is one I unearthed from my home desk a few days ago.

I thought this could be a good place to put other similar research/ discussion articles to improve our general pool of knowledge

Enjoy the read, I will ask questions and mark you later.


https://cdn2.imagearchive.com/quadraphonicquad/data/attach/61/61727-Vario-MatrixScan-210420-0003.pdf

Good idea, Chucky, to start a dedicated thread to this instead of so much posted randomly. And I can't begin to tell ya how gratifying it is to see my old article from over forty years ago posted again. I had read so many individual articles, patents, & white papers written about Quad that I wanted to consolidate that into one piece, going from basics to advanced at least for QS.. @par4ken was also a contributor to the MCS Review. He posted a few years back the same article but things get buried fast on QQ so it's good to have in place in this new thread. In fact Ken also posted another favorite article I did called Uncle Sam's Department of Quad. This was abut all the quad & audio patents I thought would be interesting.

I've liked to think the Survival Guide might have been the basic working knowledge that gave QRXRstore or QuadBob (when he was doing good) their start. Now i find out it might have been useful in the early days of R&D at Involve. How cool is that?

There is an interesting contrast between SQ & QS decoding in the vintage analog mode. SQ always required a basic decoder with quality phase shift networks to begin with. Then logic decoding or Tate DES can be used to enhance the separation. It always seemed to me that each new SQ tech development was just the latest band aid to get it to work right. But of course the Fosgate 101A did sound pretty wonderful. Meanwhile with Sansui's system the decoding and separation enhancement was all done together in what I think is an elegant solution to a tough problem.

Funny story about Sansui & QS... Sansui was not a big name in the audio stores in my area back then. Everything was Kenwood/Pioneer/ Sony SQ. So that's what I went with. I had to actually build a two band QS Vario-Matrix kit from Photolume to be able to hear QS. I was blown away, esp by the stereo to surround effects in the Synthesizer mode.

 

[kfbkfb]

Anyone have the decoding equations for "Phase Matrix" (SQ) decoding using QS (IIRC, this and the Sony SQD-200/1000 decoders were the 1st variable blend/matrix decoders for SQ)?


Kirk Bayne

 

[DuncanS]

Here is a link to the one I posted back in 2015 from Wireless World May 1977 on BBC Matrix H

https://www.quadraphonicquad.com/forums/threads/matrix-h-articles.19991/#post-233166

 

[barfle]

I’m pretty sure I have a file full of quad stuff, including just about every US patent (I was a patent examiner for six years) on the topic. Some AES stuff, too. I probably don’t need any of it any more,

Not sure I’ll be scanning all that stuff any time soon, but I will probably list what I’ve got and if there are any requests, I’ll scan and post it.

 

[par4ken]

There is an interesting contrast between SQ & QS decoding in the vintage analog mode. SQ always required a basic decoder with quality phase shift networks to begin with. Then logic decoding or Tate DES can be used to enhance the separation. It always seemed to me that each new SQ tech development was just the latest band aid to get it to work right. But of course the Fosgate 101A did sound pretty wonderful. Meanwhile with Sansui's system the decoding and separation enhancement was all done together in what I think is an elegant solution to a tough problem.

I have always been on the opposite side of this argument with Scott and Chucky. While the QS vario-matrix scheme has merit, remember that the early QS decoders employed a fixed decode circuit with very poor 3 dB separation figures between adjacent channels. They then patched that up with a weird phase modulation scheme. Even a QS vario-matrix decoder requires a rest state, the same state that it has to return to when all channels are present equally. So QS is not really all that different from SQ.

SQ has always started off with a basic decode, that too makes perfect sense to me. The outputs can be drawn straight from there, or subjected to further enhancement. The use of high quality all pass networks and attention to proper input channel balance only makes sense. The basic SQ decoder produces perfect left to right separation, which is far more important than front to back separation.

I used the non logic Audionics decoder for years and played everything through it. I loved the effect (still do). With stereo playback the term "synthesizer" would apply as the the rear outputs were just a phase shifted mix of the stereo input. The cool part is just how good QS sounded through it! Better than through those pre vario-matrix decoders! To quote the inner sleeve of the Carole King Music LP "the overall effect is surround sound". Surround sound had a slightly different meaning back then, simply meaning surrounded by sound not necessarily discrete sources. It was a much better "phase modulation" effect than with a QS decoder!

That psychoacoustic surround effect is mostly lost when enhancement is added. That is the price you pay for more discrete sound.

 

[armyjazzer]

Thanks for posting. I love looking at this stuff. Keep 'em coming!

 

[kfbkfb]

https://www.quadraphonicquad.com/fo...in-the-lab-and-in-the-home.24231/#post-357495

(some [BBC] tests of logic assisted SQ [w/gain riding] and QS [vario-matrix] decoders and some Matrix H info)


Kirk Bayne

 

[nickleb474]

Hi! Does anyone know how Dolby matrixed the height channels into Dolby Pro Logic IIz 7.1 discrete recordings? Furthermore, is it possible to create an Lt/Rt DPLIIz 7.1.2 downmix with height channels matrixed in? I'm pretty sure these are the DPLIIx encode equations for 7.1 to 5.1 then 5.1 to 2.0:

Ls = Lss + (–1.2 dB × Lrs) + (–6.2 dB × Rrs)
Rs = Rss + (–6.2 dB × Lrs) + (–1.2 dB × Rrs)

Lt = L + (–3 dB × C) – (–1.2 dB × Ls)j – (–6.2 dB × Rs)j
Rt = R + (–3 dB × C) + (–6.2 dB × Ls)j + (–1.2 dB × Rs)j

So I was wondering if it's possible add in the height channels somewhere. I saw some DPLIIz 7.1.2 equations on MidiMagic's amazing website but I couldn't figure out how to get them to work after some testing. If anyone has any insights I'd love to hear them! Thanks for reading!

 

[chucky3042]

This is wonderful. I am having trouble finding all the stuff Disclord sent to me as my computer deleted all my stuff prior to 2014. Gimmie time chaps.

 

[chucky3042]

Hi! Does anyone know how Dolby matrixed the height channels into Dolby Pro Logic IIz 7.1 discrete recordings? Furthermore, is it possible to create an Lt/Rt DPLIIz 7.1.2 downmix with height channels matrixed in? I'm pretty sure these are the DPLIIx encode equations for 7.1 to 5.1 then 5.1 to 2.0:

Ls = Lss + (–1.2 dB × Lrs) + (–6.2 dB × Rrs)
Rs = Rss + (–6.2 dB × Lrs) + (–1.2 dB × Rrs)

Lt = L + (–3 dB × C) – (–1.2 dB × Ls)j – (–6.2 dB × Rs)j
Rt = R + (–3 dB × C) + (–6.2 dB × Ls)j + (–1.2 dB × Rs)j

So I was wondering if it's possible add in the height channels somewhere. I saw some DPLIIz 7.1.2 equations on MidiMagic's amazing website but I couldn't figure out how to get them to work after some testing. If anyone has any insights I'd love to hear them! Thanks for reading!

I do not know but I suspect it would be logic based.....if common signal in all channels AND its around 8 KHz dominant it will be the bomb drop

 

[Sonik Wiz]

This is wonderful. I am having trouble finding all the stuff Disclord sent to me as my computer deleted all my stuff prior to 2014. Gimmie time chaps.

Many years ago Disclord uploaded a treasure trove of surround sound tech stuff to the issuu website. And as I said a few years ago these articles are fading away. Some that have been around a long time now say article under review. So if ya find something you like, and it's actually there, download it & get it while you can:

https://issuu.com/disclord