Comment by gdubs

In some cases the mono mixes were the ones the Beatles themselves were present for. Some of the stereo mixes were the audio engineers experimenting on their own — this is why Beatles mono mixes are highly sought-after. Can’t recall whether Sgt. Pepper’s was a mono mix originally, but probably an easy search to find out — I’m too lazy to go to my bookshelf and flip through to the Beatles studio notes at the moment…