Does the Audio Research PH-3 Invert Polarity?

The reason for invert is EVERY stage inverts.

Actually every stage with voltage gain inverts. To have a non-inverting preamp with gain you need at least two stages of voltage gain.. an inversion and another inversion puts you back to non-inverted. In almost all cases you can get enough gain from a single stage so CJ and others choose a single gain stage followed by a buffer stage that does not invert. Why add a buffer? By it's nature a voltage gain stage has an output impedance that is too high so the buffer lowers the output impedance, has unity gain, and does not invert. Net result.. voltage gain inversion followed by buffer non-inversion = inversion.

Since you can correct for the inversion by reversing the speaker cables why add another gain stage that isn't needed?

Don't most good preamps have a polarity reversal switch?

In a perfect world they would but adding that feature means some additional circuitry that some feel degrades performance.

.

"Since you can correct for the inversion by reversing the speaker cables ..."

True enough, but since so many disks/tapes were recorded in inverted polarity, this gets to be a terminal pain in the butt. I did it for over a year, wearing out banana plugs in the process, but getting an Aesthetix Calypso (with polarity switching available via remote) was a godsend. If your speakers are really polarity-coherent, you NEED a better way to switch polarity, IMHO. Dave

For those interested, the VAS Citation I pre amp has a phase switch. I've found it useful and have been very pleased with the unit. I did have a ARC PH3 initially and when I compared it to the VAS, it was no contest, VAS was much better.

Looking at the schematic, there is a FET gain stage followed by a cascoded tube gain stage, followed by a cathode follower output. Ergo, two gain stages means it does not invert phase.