faint precession of sound on vinyl

The first Led Zep album on LP has quite a bit of this prior to each song. Never heard the CD. I once read that it was because the singer was in one room and the mic was in another for echo purposes, and the mic was picking up the original vocal in real time before it registered on the tape from the speakers. Always thought that sounded funny but who knows?

I used to think this was a problem with my cartridge alignment or tracking error of some sort. It seemed like when I switched to the 10.5i arm from the 9 sig it decreased. Maybe it only seemed that way. Thanks for the explanations on something I've always wondered about.

Print though on tape is the reason they are stored tails out.

Rwwear...I didn't know that. Can you explain how this helps.

If it was the stylus reading the signal on the adjacent wall wouldn't it change channels? I notice it is always on the same channel it is preceding.