Herman
Excellent post!
Tvad
At the risk of oversimplifying things here:
If ONE speaker has + and - (it's polarity) reversed, then the system will be "out of phase".
And no offense , but no self respecting audiophile should need a test disc to hear this -- it creates a weird, vague image, and to my ears at least, a slightly disorienting, almost uncomfortable to the inner ear wandering sound.
When I sold hi fi during college, the owner of the store thought it would be amusing to demonstrate my lack of experience by asking my opinion on a system where he had wired the Acoustat speakers "out of phase". It took me about 15 seconds to hear this.
During the recording process, however, certain things might be recording about of phase to create weird imaging effects. In addition to Jimi Hendrix, I think Roger Waters Amused to Death is known for this type of demo.
My original question of course was
what happens?
and why do some recommend?
changing the polarity on BOTH speakers.
Although the "polarity" in this case changes, it does so on both speakers, the polarity remains consistent so the signal remains "in phase".
I think I am using these terms correctly now?