Question for BlueBear about stereo

  • Thread starter Thread starter Boray
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Boray

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Hi!

You have said a couple of times that stereo is one common component L+R and one difference signal L-R. Do you in the same time mean that L stands for left channel and R for right channel, or what do you mean? Because if you mean that, then this definition can't be true.

L-R will give the difference between the channels, yes, but so will R-L. But I can kind of agree to that.

L+R however is not the description of the common component of both channels. It's both channels together = the mono presentation of the stereo sound (or the full stereo sound when presented in stereo). I agree that there is a common component to a "stereo sound", but not that it can be described as L+R. If you for example have a hihat only sounding in L, then L+R would also have this hihat even if it's not common to both channels. I would describe the common component as L /\ R, where /\ is the boolean "AND". The difference signal could likewise be described with the boolean XOR. So the total stereo signal would then be (L /\ R) /\ (L XOR R) = L \/ R where \/ is the boolean AND that in some notations is "+"... So the total stereo sound presented in stereo should be L + R. ...or as said the mono sum if it's presented in mono.

I posted this question here as you both see me as a newbie and as you see this L+R, L-R definition as newbie stuff.

/Anders
 
Thanks! I will take a look! And I will also have to make a correction. It wasn't boolean AND and XOR I was thinking about, but the corresponding operators on quantities. They are called "union" and stuff like that...

Thanks for the link!
/Anders
 
Ok, I have read it. The M = L+R is supposed to be the mono signal and not what's common to the two channels as you said. This all seems to be connected to the trick of recording with 3 mics, (or one mono for the center and one omni for the left and right)...

Can you actually widen a stereo image just by adding some of the inverted R to L and some of the inverted L to R? I have to try that...

Thanks again for the link, it was interesting!

/Anders
 
Boray said:
Can you actually widen a stereo image just by adding some of the inverted R to L and some of the inverted L to R? I have to try that...

That's how spatializers and stereo expanders work. That's also why they make the track sound thin compared to the original.
 
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