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Restoration tips: HD matrix surround™

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HD matrix surround™

What is HD matrix surround™?

It's a discrete multichannel track, originally matrixed in a stereo sound, and then hardware decoded (hence the HD) using the best, and rarer, matrix hardware decoder.

Why?

Because some vintage hardware contains certain dematrix methods different from the usual Dolby Surround, Pro Logic etc. found in every modern decoders; they had that analog sound that could be even better than newer methods.

How does it work?

The matrixed stereo track (usually encoded in Dolby Surround, but could also be DTS Stereo, UltraStereo, CHACE Surround Stereo etc.) is played in the best hardware player (laserdisc, VHS, VHD etc.) using the best cables; the stereo output go in a matrix surround hardware decoder (the older and high-end, the better) to extract at least four different channels (usually Left, Center, Right, Surround) to get a discrete 4.0 multichannel track; those four channels are then captured using two sound cards with a stereo input, one sound card with four discrete inputs, or capture the track twice using a single sound card with a stereo input.

It's possible to get a stereo surround using an hardware stereo synthesizer or a software solution; an LFE could be obtained using a low/high pass filter to route the basses to the LFE and leave the other channels bass-free, either using an hardware or a software solution.

But will it sound better than, for example, Dolby Pro Logic II?

Albeit DPL II is a great matrix surround decoder, some older technology *may* sounds better, or in a different way... at the end:

Quote:Analogue domain matrixing encoding: Dolby Surround (only one spec of its kind there, 4 channels to 2)
Analogue domain matrixing decoding: Dolby Surround
Analogue domain matrixing decoding with steering and individual channel level control through h/w logic (proprietary circuitry depending on manufacturer, with, if at its most basic can decode Dolby Surround as is, then permitted to use logo): Dolby Pro Logic
Analogue domain matrixing decoding with steering and individual channel level control through h/w logic with different emphasis on center and rear for reproducing conventional non-Dolby Surround encoded stereo music tracks: Dolby Pro Logic II

(taken here)

Any hint about which decoders are better?

I've made some researches, and the following are among the best, alternative active matrix surround decoder ever produced:
  • Shure HTS 5300 / 5200 / 5000 (Acra-Vector technology)
  • Fosgate Tate II 101A
  • Fosgate Model 3 / 3a / 4 / 5
  • Aphex ESP-7000 / Proton SD-1000
  • Harman Kardon Citation 7.0 / 5.0 (6-axis technology)
  • Lexicon LOGIC 7 (first models)
  • Involve Surround Master

avoid Circle Surround I / II and DTS-Neo 6, as a Dolby Pro Logic II seems to be always better than those.
EDIT 2021-08-24:
Even if the original Circle Surround decoder should still be avoided, Circle Surround II seems to be a very improved version - it extracts up to 6.1 channels (L C R LFE Sl Sr Sc)

About DTS Neo 6, there are various versions available: difference lies in particular to the number of bands it splits the signal, but the big problem is that it's difficult (if not impossible) to understand which version a particular decoder uses. According to Disclord, it made a good job upmixing DS encoded tracks.

My last thought: even if DPL I is IMHO the best encoder to get the 4.0 track AS CLOSER as possible to the one heard in the theaters, the others may (or may not) do a good job too; take in mind, though, that the results between different decoders could be slight or huge, hence comparisons should be made.


Is it always possible to use more than one decoder: for example using one for the Left/Right and another for Center/Surround, or add a stereo  synthesizer to obtain a pseudo-stereo surround where the decoder outputs just a mono surround.

Notes

Here we are talking about HD matrix surround™ - where HD stands for hardware decoded... of course, we could also have SD matrix surround™ - where SD stands for software decoded; there are some interesting plugins for popular software like Foobar2000, that decode somehow a matrixed track; it's difficult to say how good could be the final result, but it *seems* hardware decoders produce decoded tracks of better quality.


EDIT 2021-08-24:
LAST NOTE: if someone decides to put an HD (or SD) matrix surround™ track on a project, PLEASE ALWAYS STATE which decoder was used!
Sadly my projects are lost due to an HDD crash... Sad
Fundamental Collection | Vimeo channel | My blog
Great write up spoRv. Been looking for Aphex ESP-7000 / Proton SD-1000 for a while. There is on on the US ebay but the person doesn't know if its working or not.

That and a HTS 5300, I want that to compare it to my 5000

Another one to add is the Involve Audio. I got one cheap on ebay. It was one of the late disclord's favorites also and he posted about it on quad. And the Fosgate model 3, 4, and 5 weren't bad either.
Added them, thanks! Now, you HAVE to make some tests!!!

Also, take a look at this post: http://www.quadraphonicquad.com/forums/s...SQ-decoder
Sadly my projects are lost due to an HDD crash... Sad
Fundamental Collection | Vimeo channel | My blog
I know, its just getting the time to try all these things done. Time is what I need!

I'm familiar with the quad Wink

http://www.quadraphonicquad.com/forums/s...nd-Decoder

But seriously finding a Fosgate-Tate 101 for a reasonable price is hard. I have seen a few for sale but they go for some serious money.
(This post was last modified: 2015-06-12, 04:34 AM by PDB.)
Great idea I've often wondered about. You'd think by this time there would be a bit of software to do this without necessitating the use of old hardware. Decoding back to four channels would be first step; I'd personally leave it that way, but the upmix to 5.1 is what all the studios would then do by filtering out any low bass for an LFE and phase splitting the mono rear.

My thought is about all the old ac3 demodulators that packaged in extra decoding and RCA outs. I know my Sony EDP can do it but the display burned out. I do have the Yamaha DDP-1 which does have both PCM passthrough and Dolby surround decoding in its test mode. Since this unit is supposed to have three Burr-Brown DACs it may work well but again I need to go back and play with more test modes to be able to better tell.
Damn Fool Idealistic Crusader
Pay attention: I'm talking about Dolby Surround track, and NOT Dolby Digital... the latter could be captured, untouched, and put even on DVD/BD "as is".

At the contrary, Dolby Surround tracks decoded using software *seems* to have lower quality than hardware decoder outputs; and, for sure, some rare hardware decoders has no correspondig software version... indeed, taking for example software synths that emulates old hard synths, many of them are only close appoximations, while some can't even be compared, with hard synths be clear winners...

What I'd like to find out is someone with a Dolby Pro Logic II hardware AND software encoders who could make a direct comparison: discarding obvious differences due to the analog process of the hardware decoder, if they are pretty close this process could be useless - regarding only DPL II decoder, of course...
Sadly my projects are lost due to an HDD crash... Sad
Fundamental Collection | Vimeo channel | My blog
(2015-06-19, 08:06 PM)spoRv Wrote: At the contrary, Dolby Surround tracks decoded using software *seems* to have lower quality than hardware decoder outputs; and, for sure, some rare hardware decoders has no correspondig software version...

I'm amazed that this is still the case. What goes on in those hardware decoders that's so difficult to emulate? Is it some kind of witchcraft?
(2017-06-15, 08:55 PM)Chewtobacca Wrote: I'm amazed that this is still the case.  What goes on in those hardware decoders that's so difficult to emulate? Is it some kind of witchcraft?

You should ask to Harry Potter! Happy
Sadly my projects are lost due to an HDD crash... Sad
Fundamental Collection | Vimeo channel | My blog
(2017-06-15, 09:07 PM)spoRv Wrote: You should ask to Harry Potter! Happy

You see more of him than I do.
Has anyone tried the Dolby Surround Tools plugins?

https://shop.avid.com/ccrz__ProductDetai...DetailView

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