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In article writes:

(Mike Rivers) writes:

I believe that when someone says "I've shifted
the left channel 90 degrees from the right channel" nearly all the
time, they'll mean that they've created that phase shift at a single
frequency, typically near mid-band, with some sort of a delay.

I disagree. What I think they mean is that they have passed the stereo
input signal through the following system:

Xr --------------------------- Yr

--------
Xl --------| H(w) |---------- Yl
--------

where H(w) is a practical Hilbert transformer.

I can show you any number of practical (and calibrated) delays that
are likely to be lying around the studio ready to patch in. What's
a practical (and calibrated) Hilbert transformer, who has one, and how
much do they cost?

I stand by my original statement. I don't suggest that this is ALWAYS
the case, because in the lab (and on paper or computer) it's indeed
possible to construct such a device. But considering how many people
say "phase shift" and don't know what it really means, I think I'm
right, at least for those who know enough to convert between frequency
and time and know that 90 degrees is 1/4 of a cycle.

--
I'm really Mike Rivers )
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me he double-m-eleven-double-zero at yahoo