Height Channels Algorithm? - AVS Forum
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post #1 of 4 Old 11-12-2013, 11:03 AM - Thread Starter
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Does anyone know the formula used to simulate height channels in Dolby PL2x? I can't see to find it anywhere - must be proprietary? I do know it's some king of matrix between the fronts and surrounds. I want to add simulated height channels to my system via a MiniDSP card and don't want to buy a new AVR can can't afford a ADA or Theta class processor.

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post #2 of 4 Old 11-12-2013, 11:28 AM
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Does anyone know the formula used to simulate height channels in Dolby PL2x?
It uses decorrelated (out of phase) info from the left & right surround channels.
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I can't see to find it anywhere - must be proprietary?
I remember the Dolby website mentioning it in a FAQ when PLIIz was first released.
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I do know it's some king of matrix between the fronts and surrounds.
You're describing DTS Neo:X height channels, which are extracted from the fronts and surround-back channels.
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I want to add simulated height channels to my system via a MiniDSP card and don't want to buy a new AVR can can't afford a ADA or Theta class processor.
Use the Rear/Centre Channel plug-in on the surround outputs of your pre-pro, which will extract L+R (centre) and L-R (rear). The latter is the out-of-phase part of the signal, which can be sent to your height speakers.

http://www.minidsp.com/products/plugins/minidsp-2x4-kit-box-platforms/rear-center-channel-detail

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post #3 of 4 Old 11-12-2013, 02:05 PM - Thread Starter
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Thanks, I already have the rear center plugin and was going to use it for a rear center.

So if I use the surround L-R for heights, then that means the height channels are mono?

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post #4 of 4 Old 11-12-2013, 02:39 PM
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Thanks, I already have the rear center plugin and was going to use it for a rear center.
I would send that mono rear signal to 2 speakers spread at least 60 degrees apart behind me (a la Surround EX).
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So if I use the surround L-R for heights, then that means the height channels are mono?
Yes. As with the mono rear signal, I would send the mono height signal to 2 speakers spread at least 60 degrees apart above and forward of my listening position.

BTW, I think PLIIz height outputs are mono most of the time; might be stereo under certain circumstances, like when processing a 2-channel source, though I'm not 100% sure.

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