Impact of phase inversion by preamp

For a long time, LPs were marked as to preferred polarity. They encompassed the full gamut of recorded music from Pop to Opera.

Could you name one? I have a lot of titles in my collection and don't recall ever seeing that. The manual for my lp cutter electronics mentions nothing about it as well.

I meant that I marked polarity on the jacket, not that the LP itself was marked. The only ones I recall mentioning polarity were some D2D.

I just recalled when The Tubes "The Completion Backward Principle" was mastered, the producer, David Foster, and Fee Waybill came over with a stack of refs from all over town and New York. I'd been busting David for a few years about his 'neglect' of the mastering process. I'd heard masters and sometimes the LPs didn't 'cut it.' For whatever reason, perhaps to show I was full of [?] or the band pressured him or ????, he had multiple refs made on different lacquers from multiple labs.

At the time I think I had KEF 105.2, Yamaha separates, Oracle TT [arm, cartridge forgotten]. I'd modified both the 105's and electronics.

I forget most of the details now, except some discs were inverted polarity relative to others, verified with an oscilloscope. The best sound was a French lacquer. In the end, it was mastered at Sterling Sound. As I recall, the LP rocked!

I meant that I marked polarity on the jacket, not that the LP itself was marked.

OK- that makes more sense.

I forget most of the details now, except some discs were inverted polarity relative to others, verified with an oscilloscope.

How did you do that? You had the master tape?

some discs were inverted polarity relative to others

I only checked polarity between the reference pressings. I wanted to hear each with the same relative polarity.

As far as the mechanics, just plug a sampling scope into a tape output and check first impact. This also let me check max level and to a lesser degree compression if the wave shape was altered.

As mentioned, multitrack recording may have inconsistent polarity between tracks. I didn't record or mix the album, so I had no idea as to absolute polarity.

You seem to support my assertion that 50% of all recordings are in absolute polarity. Thus the need for a polarity (phase) switch.