Preamp inverts phase question:

For hifi systems (stereo or Home theater), as long as all the speakers are wired the same way, it doesn't matter .... all of the speakers will be in the same phase.

You are referring to what is called relative phase, which means that the connections assure that both speakers are moving in the same direction at the same time. If relative phase were to be incorrect, the symptoms would be extreme and obvious -- vague diffuse images, poor bass, etc.

The original poster is referring to what is called absolute phase, which refers to the outputs of BOTH channels being inverted in phase with respect to the program source. That will have sonic effects which are subtle, but will definitely be audible to some people listening to some recordings on some systems. Particularly on sharp transients, where the leading edge will have the wrong polarity (the ear being particular sensitive to the leading edge of transient waveforms, compared to what follows during the next fraction of a second).

An inversion of absolute phase in a preamp or power amp can and should be corrected by reversing the positive and negative speaker leads on both channels. It would be more problematical if the inversion were in a source component, because correcting it for that component would create a similar problem for the other source components.

Regards,
-- Al

I don't think one's ears can discern the phase of an orchestra or an instrument in an orchestra...and each instrument, each violin, definitely play in and out of phase with each other. So I am not sure how one would record in a way that kept the phase "accurate", given that each time a musical piece is played, the phase of any instrument on any note or transient is random.

A specific recording might sound better with one absolute phase rather than the other, but the next recording (or cut on the cd) could sound better with the other absolute phase.

What am I missing?

Almarg,
So...then it's a 50/50 shot as to which phase to use; by reversing my positive and negative speaker leads (correcting the absolute phase inversion) some recording will sound better but, some may sound better with an inverted absolute phase. What then is your recommendation: to correct for absoulte phase or to allow the phase to remain inverted?

Easy test. Play a dozen LPs, CDs, and/or reel-to-reel tapes. After you listen each one, switch the speaker connections left-to-right (+ to -, red to black, whatever) on both speakers. Play again. Do you hear any difference in any of them? If not, count your blessings and forget the whole thing (because your speakers do not reveal polarity* differences). If you do hear a difference, then decide if it's important enough for you to keep switching speaker cables or invest in a polarity-switching preamp like the Aesthetix Calypso.

* I think of this as polarity switching rather than phase switching, but it's probably best not to get into that.

On typical poorly recorded, heavily multi-miked, heavily processed material, absolute phase (or polarity, as Dopogue points out) will clearly make either no difference or a random difference. On string instruments, and many other instruments as well, I'd imagine it would also make no discernable difference, as Ghstudio points out.

However, on a high-quality audiophile caliber recording, that is done using just two or three microphones, that is minimally processed, and especially one that contains sharp percussive sounds, you can find many comments by equipment reviewers and others indicating that there will be subtle but audible degradation if polarity is inverted.

As Dopogue alluded to, some preamps even provide for on-the-fly polarity switching via remote control.

My own philosophy has been that it's easy enough to keep the system phase correct (unless, as I mentioned previously, the source components differ from one another), so I just do it and don't worry about whether or not having it wrong would make a difference.

Regards,
-- Al