[OT] Re: [vorbis] Format comparison

[Freya]

There were two kinds of quad apparenty, discrete and
matrix quad. Matrix quad was something like described
below where the channels were subtracted in some way
from the existing audio information.

Discrete quad had seperate channels for all 4 channels
(obviously this wasn't on vinyl)

Matrix quad was felt not to be anywhere near as good
as discrete quad and there was much argument about it.
I think Wendy Carlos used to write much in disdain of
Matrix quad. All very long ago.

Of course there is a lot of more modern multichannel
recordings being made too with systems such as dolby
surround.

love

Freya

--- Myles Buckley <myles at conexsys.net> wrote:
>  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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