Phase inverting preamps

I give up posting on these type of questions. Bob is right, it is simple, if an audio system has an odd number of phase inversions it will be out of phase. Some preamps have a switch to add a stage to change that kind of phase. However, if a CD was manufactured with the polarity reversed, that audio system will still have an odd number of phase inversions in the signal path and is still out phase. You end up with a sound out of phase with the polarity reversed; two different things.

It is sometimes caused by having the microphones out of phase. You will hear the difference, but it does not magically add another electrical circuit to your audio system to change your system's phase. If it does call Moulder and Scully.

In some regard your system will playing an out-of-phase sound, in phase (or an in-phase sound, out-of-phase.)

It is similar to when the AC power socket has that other type of polarity wrong. No matter which way you plug your components in, that same system with the odd number of inversions is still out of phase. Having your AC polarity wrong affects the sound, but not by reversing the phase of your system.

These reversed polarity recordings are similar. It has to be corrected at the CD player when the digital is converted to analog. There are some players that do this.

For some fun reading see:

http://www.mega.nu:8080/gallery/phase_and_polarity.html

Ah, this stuff is all bogus. Where's my Fisher-Price Close & Play when you need it : ) Sean
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Sugarbrie, I think you still have phase and polarity mixed up. I read the web site you point out and he describes it correctly. But your explanation does not mesh with his. I do not intend to be picking on you as most of the other peolpe who have posted to this thread have also used the terms incorrectly.

I am not trying to sound like a know it all here, but there are so many incorrect usages of the terms phase and polarity in this thread that it is hard to keep up. I assume that some are interested in this since there have a number of posts on this. So I'll try one more time.

Out of phase means to be shifted in time. Something occurs earlier or later in time than it is supposed to. You cannot invert phase. The term "phase inversion" makes absolutely no sense. It should be stricken from the English language. You can no more invert phase than you can invert time.

Let's say you play a low note and a high note on an amplified electric guitar at the exact same time. But when it is played back on your stereo, you hear the low note and then the high note a little later. This is a phase shift.
They have been shifted in time. Nothing has been inverted.

Let's say when you play the low note, the initial movement of the speaker cone from the guitar amplifier is out. But when you play it back on your stereo, the initial movement is in. This is a polarity inversion.

If you hook up a battery to your speaker terminals, plus to plus and minus to minus, the woofer will move either in or out depending on how the speaker is wired up. If you reverse the battery, it will move the other way. This is a reversal of polarity. It has nothing to do with phase.

If you record a single cycle of a sine wave and play it back, the cone will move one way and then the other, say first in then out. If you reverse the speaker leads it will move first out then in. This is a polarity inversion. If you leave the speaker leads but hit the phase button on your CD player, It will also reverse to first out then in. This is also a polarity inversion, not a change in phase. The button is labeled incorrectly.

So can you correct for a recording that was recorded with inverted polarity? Yes, definitely. Just reverse the leads on your speakers or hit the incorrectly labeled phase button on your CD player or preamp.

Can you correct for phase shifts? Possibly but it would be very, very complex.

I guess I agree that a recording with the polarity wrong has no affect on the phase of your system. The + signal (and minus) of DC current going through your hardwired system cannot be reverse solely based on music encoded on a piece of media, whether, CD, LP, or Tape. That would defy the laws of physics.

If you had a recording with multiple microphones, where some microphones were in phase and some out of phase, some sounds may cancel out in part, which is why the recording sounds off. You system won't be feeding post positive and negative current to both speaker terminals at the same time. I hope you agree that is impossible.

Put another way; if a system is phase correct and a recording has sounds out of phase; your system reproduces for your ears to hear, what that out of phase music sounds like. That reproduction of the out of phase sound is in phase. If you reverse your speaker cables that sound is not in phase. You are hearing an out of phase sound, out of phase. It may end up sounding even worse.