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What's wrong with Dolby Pro-Logic II?

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chucky3042

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Ooops. I'm having trouble with the Lindsey Buckingham video Trouble. It just says video unavailable. I will look for on youtube after this.
To be able to do a DPL II encode you would need to start off with a discrete mix. I am not aware of anything Buckingham has done in quad before. If so, where did the original discrete come from?
Dunno
 

kfbkfb

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Original Dolby Surround eventually had 2 "modes" for the single surround channel:

Bandlimited (100Hz - 7kHz) and Dolby B encoded (typically from VHS Hi-Fi movies)

and

5.1 downmix (full bandwidth) and no Dolby B encoding (typically from Dolby
Digital 5.1 DVDs)

Have the DPL II encoding and decoding equations been published?

Kirk Bayne
 

Sonik Wiz

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chucky3042

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The equations for involve are the same as QS but thats not where we differ, its the conditioning of the stearing constants with human hearing factors in how the matrix is applied and how we then extract and place sounds around the room where we get tricky
 

ssully

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Thanks for this, I tried this on my travel set (Logitech Z-5500) and it sounds much better than the standard setting. On my home rig I never use PLII because it sounds too narrow and the low level sort of drowns so will try that on my home-rig as well, until now I always use the all channel stereo setting (Onkyo TX-NR808).(y)
DPLIIx ((or z) sounds great in my setup. Suggestions:


-- DPLII default mode is often set to Movie. That's not what you want for music, it's very center-biased (for dialogue). If you've been using Movie, change the DPLII mode to Music mode instead. Then you can experiment with Center Width, Dimension, Panorama.

-- 'all channel stereo' is described as: 'Ideal for background music, this mode fills the entire listening area with stereo sound from the front, surround, and surround back speakers."
I have no idea what that means, but I doubt it's 'surround' as we know it.
 

malcolmlear

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The equations for involve are the same as QS but thats not where we differ, its the conditioning of the stearing constants with human hearing factors in how the matrix is applied and how we then extract and place sounds around the room where we get tricky
Hi Chucky, does this mean the encode coefficients shown in the patents are now no longer used? I believe you used 0.207 as opposed to 0.4142.
 

Marcsten

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The center channel truly is the root of all evil!
I like your style! I never really thought it was evil so much as totally unnecessary. I always thought it was originally for theaters with a wide space between the front channels. I doubt many home applications warrant it. Regardless, I use the "Chucky method" for my music room and 5.1 with the TV. Still can't really see the point in the center channel but using HDMI in the TV room so not worth messing with it.
 

Marcsten

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I agree .

I find the centre can affect one's (mine)..... auditory perception of a good surround mix via the quadrant .

For me.....the four quadrant speakers tell my ears whether or not it's a good surround mix . The centre can interfere..............most especially if it's too fn loud. I turned mine facing backwards and then threw a towel over it.
I put mine behind the 65 inch TV!
 

chucky3042

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Hi Chucky, does this mean the encode coefficients shown in the patents are now no longer used? I believe you used 0.207 as opposed to 0.4142.
Hi Malcolm

Yes/ no. In our SM decoder we use the basic QS 0.42 thing as fixed parameters but in the encoder we run a triband vario matrix on the parameters (more centered on 0.25 actually) depending on the surround/ music content/ spectra it can vary from a theoretical low of 0.21 to a high of 0.42. Its a very dynamic thing
 

chucky3042

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I like your style! I never really thought it was evil so much as totally unnecessary. I always thought it was originally for theaters with a wide space between the front channels. I doubt many home applications warrant it. Regardless, I use the "Chucky method" for my music room and 5.1 with the TV. Still can't really see the point in the center channel but using HDMI in the TV room so not worth messing with it.
Hi Marcsten
I do actually recognize the need for a center channel for the suckers that are not in the sweet spot and yes it really did open up the possibility for the whole family to enjoy movies etc. But it always has been a poor band aid that actually puts the image BELOW THE TV whereas the visual is in the middle of the TV- THIS BUGS ME. Works OK in the cinema as they use perforated screens.

We at Involve have our "secret weapon" that abolishes the need for the center channel, in fact when in use no one cares where they sit in the room! Its called SST and it is in use with our Y4 system

Ah screw it, its patented.....so here it is
It actually works best with highly directional speakers (i.e. electrostatics)
 

Attachments

ar surround

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...We at Involve have our "secret weapon" that abolishes the need for the center channel, in fact when in use no one cares where they sit in the room! Its called SST and it is in use with our Y4 system...
Does SST somehow work in the 4.0 mode on the SMv2? I thought it was only a stereo application.

I do actually recognize the need for a center channel for the suckers that are not in the sweet spot and yes it really did open up the possibility for the whole family to enjoy movies etc. But it always has been a poor band aid that actually puts the image BELOW THE TV whereas the visual is in the middle of the TV- THIS BUGS ME. Works OK in the cinema as they use perforated screens.
The solution...

drill.JPG
 

chucky3042

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Does SST somehow work in the 4.0 mode on the SMv2? I thought it was only a stereo application.



The solution...

View attachment 61866
Its works for both stereo and surround, the bigger the speaker panel the more effective. You need a special speaker plus 2 amplifier channels per speaker (that's why the Y amp is a 10 channel amp- 4 speakers, 2 woofers)
 

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ssully

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I like your style! I never really thought it was evil so much as totally unnecessary. I always thought it was originally for theaters with a wide space between the front channels. I doubt many home applications warrant it.
That would be incorrect on both counts.



Here is what James 'JJ" Johnston has to say about three front channels vs two:

As far back as the 1930’s, Fletcher, Snow, and others showed
that 3 front channels provides a much better depth illusion.
Why? Because at half the angle, the time delay is
smaller (moving the interference up in frequency) and the
higher frequency is more highly attenuated
(reducing the size of the timbre change).
There are other reasons to have at least 3 front channels.

With 3 front channels, and using nearly coincident miking
techniques, it is possible to create a good illusion of the
front soundfield without having depth or elevation problems.

Aside from avoiding the problem of interference,
non-coincident 3-channel miking has other good
effects, specifically a wider listening area,
measured by subjective test to be 6 to 8 times the
listening area available in the 2-channel presentation.

and as Floyd Toole notes in his book (boldface is mine):

The stereo phantom center will suffer from a significant dip in the spectrum around 2 kHz because the sound from both loudspeakers reaches both ears at different times. This interaural crosstalk cancellation is the first dip in an acoustical interference comb filter.

The consequence of this is that the sound quality of a phantom center image (usually the featured artist) [or dialogue, in a movie] in stereo recordings is fundamentally compromised. Those who believe that phase shift is audible and that waveform fidelity is essential must think again, because for this sound image both are seriously corrupted. As an illustration I recommend a simple experiment. Arrange for monophonic pink noise to be delivered at equal level to both loudspeakers. When seated in the symmetrical sweet spot , this should create a well defined center image floating midway between the loudspeakers. If it does not, something is seriously wrong. If it does, consider what you hear when you lean very slightly to the left and to the right of the symmetrical axis: the timbre of the noise changes. It will be more obvious the closer you sit to the loudspeakers placing you in a stronger direct sound field. It will also be more dramatic in acoustically dead rooms. In fact it is possible to find the exact sweet spot by simply listening to when the sound is dullest. Moving even slightly left or right of the sweet spot causes the sound toe get audibly brighter. It is much more exact to find the sweet spot by listening to the timbre change than by trying to judge when the center image is precisely localized in the center position. There is nothing faulty with the equipment or setup; this is stereo as it is: flawed.
 

malcolmlear

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Hi Chucky, thanks for the clarification about your system. Variable encoding sounds a great idea and maintains decoding compatibility. I've always wondered how much better SQ may have been if the encoder had dynamically moved from front to back orientation dependent on incoming source material.
 
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