Stereophile test CD2 In/Out of Phase test:question

That test shows whether your speakers are in phase with each other, it doesn't show absolute phase. That means if they are being fed the same signal the cones will be moving in and out together. If the phase is reversed then when one speaker is moving in the other is moving out.

If your speakers are in phase, and you reverse both speaker cables at the same time, they are still in phase. You just reversed the polarity.

FYI, the correct term is really polarity, but phase is used so often it has come to be accepted as being correct.
Phase has to do with time.
Polarity has to do with whether the signal is positive or negative, or in the case of a speaker, whether it is moving in or out.

If two signals reach their peaks at the same time they are said to be in phase. If one signal reaches it's peak earlier or later in time than the other then they are out of phase. If you switch the leads on your speakers you haven't changed any timing, you have reversed the polarity.

The test is for absolute phase or polarity not for one speaker being out of phase with the other. Only careless installation would have that happen.

Changing the leads at the amp or at the speaker equally deal with change the absolute phase.

Remember, however, that many recording are recorded out of phase and some with some microphone in phase and others out of phase.

Some preamps provide a phase switch, although many add another stage to do so, which hurts more than it helps.

I never looked at the booklet before. If you only listen to the CD then my assessment is correct. Track 2 is labeled "channel phasing, not absolute phase. "Having "a clearly defined central image" as the recording tells you to listen for has only to do with the speakers being in phase with each other, not absolute phase.

Then if you read the booklet the discussion is all about absolute phase. So it appears that it can be used for both.

It is probably the common confusion in the booklet as it is played "in" phase and then "out of" phase. If it is really one channel out of phase with the other, which channel would be reversed for "out of" phase?

Tbg, it really is one channel out of phase (actually inverted polarity) with the other on the recording and then the two channels are in phase. If you reverse the wires on just one of your speakers the image will be centered when he says the signal is out phase and diffuse when he says they are in phase.

Your question is the tricky part. Once they are both the same polarity (image centered when he says they are in phase) the idea is to listen to the part when he says they are in phase, then reverse both speaker leads to invert the polarity and try it again. The bass should sound more natural one way or the other. As Rives pointed out, some people are more sensitive to this than others. Or perhaps some know what to listen for and others don't. I've never tried it, but I will later today to see if I can hear the difference.