Delos Dolby Surround natural (matrix) surround sound encoding

[kfbkfb]

The booklet in the Delos CD DE 3196 states:
"Delos' Dolby Surround recordings are encoded naturally
during the basic recording session through the use of
microphone techniques that randomize stereo pickup
of ambient and reverberant cues in the recording space."

How about monitoring stereo mixdowns through a Dolby
Surround Pro-Logic II (Music mode) decoder (a Dolby
Surround encoder would not be used).

This would be a way to "add value" to recordings intended
for stereo media, there would be "something extra" (some
surround sound effects) while avoiding dual inventory type
problems.

Kirk Bayne

 

[neil wilkes]

Because this approach really does not work well in practise.
Matrix encoding uses steering, and this causes poor placement, and serious phase cancellation issues due to the use of comb filters to "extract" the monophonic surround channels.
The only way this can work to any degree of success is to set up a standard surround mix in the first place, encode this to Lt/Rt with the matrixing.
Just playing back a stereo mix through this type of decoder generally results in a thin, washy sound with no punch, clarity or definition.

Having just said that it does work reasonably well in some cases, but not in the vast majority.

 

[sspsandy]

Neil, here's a question. I read that when Dolby Digital 5.1 came out on DVDs, there was a spec that required the discs to also contain a stereo track that was Dolby Surround encoded. Is this true? It has been my experience that DVDs contain this encoding, since if I run it through the Tate or through the Fosgate Pro-logic II processor in my car, it plays back like the 5.1 DD track. Some of the live music DVDs have excellent surround effects from the stereo track. (example: Grateful Dead - Views from the Vault has drums that pan all around)

As I understand it, the matrix decoder directs out of phase musical information to the various channels. Depending on how the decoder implements the assigning of channels has a lot to do with how discrete it is, and if the stereo source is encoded, this info has been directed to certain channels. Thus, effects like sound panning around all the channels, or coming from key places can be created.

I've found that no matter whether SQ, QS, Dolby Surround, or Prologic II encoding, the Tate and the Fosgate Prologic II processors do an excellent job with it, sometimes better than the digital multitrack recording.

For a cd that I believe to be Dolby Pro-Logic II encoded, check out Linkin Park - Meteora. Has as much going on as their DVD-A of Reanimation, which incidently appears to have an encoded stereo track as well.

 

[neil wilkes]

Nah - it is not a compulsory thing as such. However, there is a flag you can set in DD metadata that will make the downmix Dolby Surround Compatible. That is to say it can also incorporate an Lt/Rt instead of just an L/R stereo stream.
The centre channel and Surround channels get a downmix setting and there is also a 90 degree phase shift option in the encoder. Normally this would be set to "off" unless the disc in question is a DVD-V title, or a video type disc.
The matrix decoder also uses delays and a comb filter in addition to the phase trick, and with some material it works well, but in others it just sounds thin.
Usually it will be better if the stereo component is an Lt/Rt instead, as mentioned earlier. But this is usually derived from the original surround mix, although it could be a separate stream if the space is there to do it - after all, it would only be 192kbps of space. In this way, the stereo mix is simply ProLogic (or Dolby Surround, as it is still called) encoded, and this gets called "Stereo".

It is definitely not as good as a well mixed discrete track though. Close, but not quite there.

 

[sspsandy]

For those of us with only a stereo source in the car, a Pro-Logic II processor will give you a reasonable surround environment. And any surround encoded stuff lights it up nicely. Eventually I'd like to add DVD-A capabilities in the car.
Also, a nice matrix processor for the tv, as well as stereo videos, DVDs, cds, and lps, adds quality surround where otherwise you'd just have stereo.

I find matrix surround quite enjoyable, regardless that DVD-A is sharper, clearer, and more discrete. Even in my old Citroen I use a Craig cassette player from the 70's that has a built in matrix system, which was designed to create quad in the car. It is far from discrete, but creates a cool surround sound environment, with distinct differences between front and rear channels, as well as separation side to side. I also have an SRS Labs Circle Surround quad processor for the car, I have to get around to hooking it up to hear what it sounds like.

 

[neil wilkes]

SRS is very, very similar to ProLogic but with a little more control over the output, as (at least there is in my decoder) a "TruBass" option, and a sort of Clarity option too.
Not bad - but not great either. It seems to decode very quiet surround channels.
Not even close to as good as an SQ decoder. But then again, nothing like the price of an SQ decoder either.