SQ Shadow Vector Soundfield Mapping

[Sonik Wiz]

I notice what appear to be LED's around the level control. Being 4 of them I assume it represents the decoded output.

But is the level control function at the input or output to the decoder? And if the latter how sensitive is the box to input level variations?

BTW, really cool Shadow Vector logo & gotta love a name like Leartronix!

 

[Owen Smith]

This type of thing was done ~20 years ago with the SQ encoded stereo master for the Buddy Rich video (SQ -> Tate SQ decoder -> DD & DTS 4.0 DVD).

And as I understand it the Tate used wasn't working very well and the results aren't great.

Live decoders are very useful for people playing things at home. But they're not necessarily the best way to go about a "once in 20 years" decode of a hi res transfer of the encoded master. You can leave a computer chewing a brick for a week to do that decode.

 

[kfbkfb]

The CBS Labs 4212 SQ position encoder has 24 specific locations (including LF,CF,RF,RB,CB,LB) and provides optimum SQ encoding for each of these 24 locations.

Are there any plans to design a logic directed SQ decoder that will decode to each these 24 positions (depending on which of the 24 positions is loudest at any given moment) rather than the current 6 locations the Shadow Vector decodes?

4212 front panel:
https://www.worldradiohistory.com/Archive-All-Audio/Archive-Audio/70s/Audio-1973-07.pdf#page=24

Kirk Bayne

 

[Soundfield]

The CBS Labs 4212 SQ position encoder has 24 specific locations (including LF,CF,RF,RB,CB,LB) and provides optimum SQ encoding for each of these 24 locations.

Are there any plans to design a logic directed SQ decoder that will decode to each these 24 positions (depending on which of the 24 positions is loudest at any given moment) rather than the current 6 locations the Shadow Vector decodes?

4212 front panel:
https://www.worldradiohistory.com/Archive-All-Audio/Archive-Audio/70s/Audio-1973-07.pdf#page=24

Kirk Bayne

Where do you get the idea that Shadow Vector decoding can only resolve 6 'locations'?

 

[kfbkfb]

I didn't check, just from memory, could be wrong (I'll review this thread again).


Kirk Bayne

 

[par4ken]

I didn't check, just from memory, could be wrong (I'll review this thread again).


Kirk Bayne

As I understand it the Shadow Vector is similar to Vario-matrix. As such it should be able to resolve any position. SQ decoding requires three axis to work on, QS only two. That is why SQ (phase matrix) via Sansui is considered to be half logic.

Tate has six control outputs, perhaps that is what you were thinking of. Despite being limited to only six control signals (IMHO) Tate can still resolve intermediate positions. I can't comment further without auditioning the SV unit! Rather exciting that it (Shadow Vector) was designed to decode virtually anything!

 

[malcolmlear]

I notice what appear to be LED's around the level control. Being 4 of them I assume it represents the decoded output.

But is the level control function at the input or output to the decoder? And if the latter how sensitive is the box to input level variations?

BTW, really cool Shadow Vector logo & gotta love a name like Leartronix!

Hi,
When optical input isn't detected input switches to analog. The level control allows adjustment in this mode to maximise dynamic range of the ADC. The LED above the level control aids this adjustment.

 

[malcolmlear]

As I understand it the Shadow Vector is similar to Vario-matrix. As such it should be able to resolve any position. SQ decoding requires three axis to work on, QS only two. That is why SQ (phase matrix) via Sansui is considered to be half logic.

Tate has six control outputs, perhaps that is what you were thinking of. Despite being limited to only six control signals (IMHO) Tate can still resolve intermediate positions. I can't comment further without auditioning the SV unit! Rather exciting that it (Shadow Vector) was designed to decode virtually anything!

Yes, its a full 3 axis variomatrix decoder in all modes. Although the Z axis is largely redundant in QS and similar modes it still plays a part in maintaining constant power in 'off loci' sound images.

 

[malcolmlear]

The CBS Labs 4212 SQ position encoder has 24 specific locations (including LF,CF,RF,RB,CB,LB) and provides optimum SQ encoding for each of these 24 locations.

Are there any plans to design a logic directed SQ decoder that will decode to each these 24 positions (depending on which of the 24 positions is loudest at any given moment) rather than the current 6 locations the Shadow Vector decodes?

4212 front panel:
https://www.worldradiohistory.com/Archive-All-Audio/Archive-Audio/70s/Audio-1973-07.pdf#page=24

Kirk Bayne

Hi Kirk,
Not sure where the 6 positions comes from, however the decoder employed is based on the Lynn Olsen's full 3-axis decode method outlined in his patent. This allowed perfect SQ constant power decoding at any position of the Scheiber sphere. By adopting different equations, the same decode method could be applied to all 2 channel matrix based systems.

 

[malcolmlear]

Is that Pro Logic II Movie mode, with no Centre channel?

Personally I've had a fair amount of use of Pro Logic II Music mode on my previous AVR when listening to Proms concerts on BBC Radio 3. It's one of the things I've lost when I finally gave in and changed AVR.

Yes, full range 4 channel without the Pro Logic pumping all over the place.

 

[Owen Smith]

Yes, full range 4 channel without the Pro Logic pumping all over the place.

I must confess I've never been aware of Pro Logic II pumping. I've always considered it slow, dull and predictable and thought that was how it avoided pumping.

DTS Neo 6 on the other hand I couldn't tolerate, on my old Arcam AVR350 it spat random high frequency sounds out of random speakers at odd times which was very objectionable.

Dolby Surround Upmix that I'm having to use on my new AVR is more active than DPL II and does occasionally do something silly, putting sounds where they clearly shouldn't be.

I'm now trying to find an ADAT to HDMI converter so I could use the Shadow Vector decoder with my new AVR. Sadly it doesn't look like anything exists, or if it does it is part of very expensive semi pro mixing gear.

 

[malcolmlear]

To make things clear, the HDMI sockets are wired for 12S, as used by several amplifier companies such as PS Audio.

 

[malcolmlear]

I must confess I've never been aware of Pro Logic II pumping. I've always considered it slow, dull and predictable and thought that was how it avoided pumping.

DTS Neo 6 on the other hand I couldn't tolerate, on my AVR it spat random high frequency sounds out of random speakers at odd times which was very objectionable.

Dolby Surround Upmix that I'm having to use on my new AVR is more active than DPL II and does occasionally do something silly, putting sounds where they clearly shouldn't be.

I'm now trying to find an ADAT to HDMI converter so I could use the Shadow Vector decoder with my new AVR. Sadly it doesn't look like anything exists, or if it does it is part of very expensive semi pro mixing gear.

I personally use S/PDIF optical input and 4 channel phono out.

 

[malcolmlear]

I personally use S/PDIF optical input and 4 channel phono out.

Yes, slow, but still bouncing (possibly that's what the director wanted). I think using multiband also helped stabilize things.

 

[malcolmlear]

Will this Shadow Vector decoder be the 1st logic assisted Matrix H decoder (not an adapted QS variomatrix decoder)?


Kirk Bayne

Pretty sure thats the case. The decode loci is as documented in 'Quadraphony: developments in Matrix H decoding' 1976.
Here's the loci plot created by the decoders equations.

 

[Owen Smith]

I personally use S/PDIF optical input and 4 channel phono out.

My current Arcam AVR31 doesn't have multi channel analogue inputs, only HDMI for multi channel. It's become too constraining on choice and other features to maintain multi channel analogue inputs unfortunately.

 

[Owen Smith]

Pretty sure thats the case. The decode loci is as documented in 'Quadraphony: developments in Matrix H decoding' 1976.
Here's the loci plot created by the decoders equations.

There are two different versions of Matrix H, generally denoted by years (I forget what they are). Whichever one you pick for a decoder there will be some sources that don't decode correctly.

 

[Owen Smith]

To make things clear, the HDMI sockets are wired for 12S, as used by several amplifier companies such as PS Audio.

I wonder if PS Audio or similar sell something that will go from I2S to multi channel HDMI?

EDIT: the one thing I have found is DisplayPort to HDMI converters. Assuming they handle multi channel audio, I then need ADAT or I2S to DisplayPort, which is more likely to exist since DisplayPort licencing fees are much less onerous.

 

[malcolmlear]

There are two different versions of Matrix H, generally denoted by years (I forget what they are). Whichever one you pick for a decoder there will be some sources that don't decode correctly.

Yes, most published papers around 1976 referring to system H have centre front sitting at around 47-48 degrees. 1977 onwards various revisions (HJ, UHJ, BHJ) had centre front at 30 degrees.

 

[kfbkfb]

Yes, most published papers around 1976 referring to system H have centre front sitting at around 47-48 degrees. 1977 onwards various revisions (HJ, UHJ, BHJ) had centre front at 30 degrees.

Will there be 2 Matrix H decode modes - H(76) and H(77+)?


Kirk Bayne