Reversing Polarity -- Voodoo or Easy Tweak?

Tvad and others

Didnt know it was called "absolute phase" - this is what was recommended on the first edition Dave Grusin vinyl.

So I guess the answer is like biwiring: it depends?!

Absolute phase, and phase (what Eldartford calls "relative" phase) are two different things, thus the difference in approaches to wiring the speakers to correct the problem.

The correct term when talking about wiring speakers is polarity as stated in the original question, not phase.

Phase has to do with time, polarity has to do with whether a signal is going positive or negative. If a speaker is wired with the wrong polarity it will be going out when it should be going in, and vice versa. I have friend who claims he can tell when it is reversed because a vocalist will sound like they are gulping air instead of exhaling.

When 2 signals are out of phase it means that one or the other has been shifted in time, it occurs earlier or later in time than originaly produced. One example is a crossover network. They not only attenuate the signals outside their passband, they also phase shift them so they occur at a different time relative to those in the passband.

The fact that many manufacturers use the terms interchangeably adds to the confusion, just as Eldartford did in his post. In the first part where he is talking about wiring the speakers the correct term is polarity. In the second when he talks about the Buffy Sainte-Marie recording the correct term is phase. This deliberate phase shifting is the same thing Hendrix did to get that swirling effect with some of his recordings.

Well, I thought I understood this topic, but I'm as confused as I've ever been.

Herman, your explanation makes sense, however I want to understand the effect of polarity, and the solution.

I own Stereophile's Test CD3, on which track 2 is titled "Stereo Channel Phasing". The description, and effect appears to be what you're referring to as polarity. Quoting from the Stereophile Test CD3 text:

What you should hear: In a conventional stereo system, a centrally placed listener should hear the image of the in-phase noise occupying a very narrow space centered between the loudspeakers, If the sound "splashes" to the sides at some frequencies, or the image is broadened at all frequencies, then there is something suspect in your system-most probably a loudspeaker or room-acoustic problem. The image of the out of phase noise should not be centered; in fact, it should generally be very hard for you to point to where it's coming from. With some loudspeakers, however, the out-of-phase noise might appear to come from a point to the outside edge of either the left or right loudspeaker. If you don't hear these clear distinctions between in and out of phase noise, or if you hear them reversed, try inverting the connection to one of your speakers.

The way I understand this is simply...from amp to speaker, connect plus to plus and minus to minus on both speakers. Connecting plus to minus on only one speaker usually results in the out of phase (polarity?) phenomenon mentioned in the quote from Stereophile.

Do I have this right? Is Stereophile referring to polarity when they speak of phase?

Cripes, my head is spinning...maybe it's out of absolute phase.

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?