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Join Date: Oct 2001
Location: Monterey Park, CA
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If the new output is extracted from a pair of discrete channels, then none of them are discrete any more.
Simple example: extracting a centre output from a 2-channel CD. Sounds (e.g., vocals) that are exactly the same level and phase in the L/R speakers will phantom image at the centre of the soundstage. Those vocals can be extracted and sent to a centre speaker placed at the centre of the soundstage, where those sounds were going to image anyway.
However, that means you'll hear the vocals in triple-mono, coming from all 3 front speakers. So, it's not enough just to send those sounds to the centre speaker. The new centre signal has to be inverted and sent as an out of phase cancellation signal to the original L/R channels so you don't hear the vocals from your L/R speakers.
So 2 input channels were turned into 3 outputs. The new centre output is obviously matrix extracted, not discrete. The new L/R outputs no longer have the vocals in them, so they are no longer the same discrete channels that were on the disc, they're as matrix extracted as the centre.
Same holds true when you split a pair of channels (surrounds) into 2 pairs of outputs (sides and rears). Those new side and rear outputs are both different from the incoming discrete surround channels. Same with extracting heights and wides. The original discrete channels have information sliced out of them, so they are derived from the processing, no longer the original discrete channels.