[OT] Re: [vorbis] Format comparison

[Myles Buckley]

 merijnv at sci.kun.nl pondered the following....
 Subject: [OT] Re: [vorbis] Format comparison
 >Eh, just a (seemingly offtopic) question, but how do you create a 4
channel
 >lp ? With just one needle ? 
 >-- Merijn

In a nutshell.

Normal LP has two halves in the groove - the L and R channel.
A Quad channel LP still has to 'halves' in the groove.  Each channel is
actually BOTH the front channel added in a linear fashion to the BACK
channel information which is riding on a 'carrier wave.'

If I recall correctly (and I probably don't) the back channel is AM coded on
a high frequency signal (80khz or 160khz comes to mind.)

A quad capable receiver de-multiplexes the back channels and subtracts them
from the baseband signal to send only the front signals to the front
speakers and back signals are then sent to the back speakers.

I now return you to an on-topic list....

Myles

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