RIAA vs Columbia vs Decca

Lewm, I think Chakster was referring to "Absolute Polarity". That will open up a can of worms. Some claim that it makes a difference, others claim that they can't hear any difference. I believe JGH was in the latter camp. I definitely reside in the former. That said, older LPs are all over the map when it comes to polarity. Even new releases do not always hew to the standard. Diana Krall's album "Quiet Nights" comes to mind. The new Eva Cassidy releases which are compilations from various sources has some songs recorded in positive polarity and some in inverted.

If you think about it, air is not a linear medium. One glance at the adiabatic pressure/volume curves of an ideal gas will convince one of that. This results in the asymmetric distortion of the sound wave. Common sense would suggest that inverting an asymmetric wave will change the sound. I guess the take away here is if one's system - ear/brain is sensitive to absolute polarity then it is very handy to have polarity invert on remote control.

Vintageaxeman,

The Rek-o-kut Re-Equalizer does what you suggest, i.e., re-equalizes an already RIAA-equalized signal to another EQ curve. It could also be used in the tape loop of a preamp. But it's intended for mono LPs & 78s and sums a stereo signal to mono.

Exactly, thanks John
A note on polarity can be found on George Cardas (frequency Sweep and Burn-In) LP. Very interesting!

Regarding absolute phase/polarity, on recordings which are heavily multi-mic'd and are subjected to extensive post-processing and mixing (as many and probably most recordings are in recent decades), and assuming that multiple instruments and/or voices were recorded, as I understand it the finalized mix is likely to consist of a conglomeration of randomly phased sounds from each of the performers.

In those cases, while the two polarities may or may not sound somewhat different, it seems safe to say that neither polarity can be thought of as being correct. Maintaining absolute phase/polarity would seem to be meaningful pretty much just on recordings that were engineered with "purist" mic techniques (meaning just two or three mics), and minimal post processing. Such recordings would include many of the classical releases on RCA, Decca, Mercury, etc. during the early years of stereo.

Also, it wouldn't surprise me if in some cases where listeners perceive differences between the two settings of a preamp's polarity inversion switch what they are actually hearing is changes in the sound of the preamp itself, that result from the differences in the preamp's internal circuit configuration between the two settings.

Regards,
-- Al

Also, it wouldn't surprise me if in some cases where listeners perceive differences between the two settings of a preamp's polarity inversion switch what they are actually hearing is changes in the sound of the preamp itself, that result from the differences in the preamp's internal circuit configuration between the two settings.

Not the case with my set-up. Polarity inversion just reverses the phono preamp's line out transformer's secondary winding.