Phase effects on stereo mixes

[Brian Gygi <bgygi@xxxxxxxxxxx>]

I am forwarding this for Gilbert Shuster, an engineer I know.  So,
*please* direct all responses to gbshust@banet.net:

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I am an audio engineer and I am curious about some things I have
noticed:

If the phase of one speaker is reversed, it is the bass that disappears
as opposed the treble, that is it gets very thin.  But at the same time,
the stereo separation seems to increase - the sound field seems to be
more spread out.  I would like to know if anyone can explain this.  I
understand that the bass instruments are probably more centered in the
mix than others (this is pop music) and would have more phase
cancellation than instruments that are panned such as guitars, but this
also happens when I reverse the phase of one of the overhead mike pairs
on a drum kit.- the sound gets very thin but also more spread out.

I would be grateful for any ideas or explanations, or if someone knows
of a other groups for audio-related technical questions, please pass
that along.

Gilbert Shuster