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Subject: RE: Stereo separation
From: Andreas Stemmer (groovingandi_at_gmx.de)
Date: 2003-11-19


Michael Hentschel wrote:
> I have just one question concerning this issue: what difference would
> I hear/see on a scope if the stereo separation was wider (e.g. with
> the two different frequencies on left and right)? (I'm not so firm in
> audio business...)

I used a 500Hz sine on the left and a 1kHz sine on the right channel.
With normal stereo setting, you can see a pure sine on each channel. The
mono setting mixes both channels and you get the addition of both channels
on each channel (if the difference between the two frequencies is not too
large, it looks like a fast sine modulated with a slow one).
The "stereo narrow", "stereo wide" and karaoke settings are a little bit
tricky, but they are all only a clever addition of the two sines. The
"stereo narrow" setting is a mixture of normal stereo and mono which means
that only a small amount of the left channel is added to the right one and
vice versa. The opposite effect (stereo wide) can be achieved by subtracting
small amounts of the left channel from the right channel. This way the parts
of the signal which are the same on both channels (the center information)
is getting damped whereas the information with most differences between the
two channels (the stereo information) gets boosted.
I'm not sure about the karaoke setting, but I think it's just an extreme
case of the stereo wide setting. The vocal information is exactly in the
center in most songs and totally eliminated by subtracting the two channels.

Andreas



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