Reversing Polarity -- Voodoo or Easy Tweak?

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?

Cwlondon, I understood you in your first post. Few are stupid enough to wire one speaker out of phase with the other. Absolute polarity is a different matter. I wish I had an easy way to have switchable polarity, so that I had a choice, but I don't have. Even cheap digital players used to have this, but no longer. I am not about to change speaker leads for each cd or record.

In the past, on perhaps 10 percent of my records changing the absolute polarity made a great difference. On about 30 percent it made no difference.

The Grusin LP was recorded with the absolute polarity reversed. Shefield realized it after the fact and this is the reason for noting it on the cover. About half of the LPs and CDs have the polarity reversed. Some of the offenders are Mercury Living Presence, RCA Living Stereo, Capitol, MCA, Decca/London, DG and Warner. When your ear is trained to hear this, it will take about 3 second to pick up on it. I don't do vinyl anymore so it's easy for me to correct with the polarity switch on my Theta DAC. Then I mark the CD insert with a green (correct)or red (180 degrees)sharpie. A polarity switch on the preamp's remote would be even easier. Listen to a recording of Nat King Cole on Capitol both ways. There is a huge difference in these recordings and it's easy to hear. If you can't hear the difference, well...

Cwlondon wrote:

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".

This is reversing Absolute Polarity (I mistakenly referred to this as Absolute Phase in an earlier post). In my experience, when the signal is in correct Absolute Polarity, the sound is somewhat fuller, and more complete. The stereo image will remain focused and centered just as when the polarity is maintained plus to plus, and minus to minus.

It's interesting to note that one manufacturer of equipment I own refers to this as Absolute Polarity, and another manufacturer refers to this as Absolute Phase. No wonder there's confusion!

Regarding your statement about the necessity of a test disc to hear correct phase, I don't believe the use of one makes the listener a less-than-self-respecting audiophile any more than the use of a tape measure makes a less-than-self-respecting carpenter. Frankly, for someone new to the hobby, which we all were at one time, a test disc can be an extremely useful tool. Futhermore, the Phase track on the Stereophile Test CD is a quick and easy way to double check for correct polarity (phase) without uncertainty or guesswork.