"That's another reason for its fluctuating reputation: the Pepper that blew minds out in 1967 was mono, but later generations heard it in the diffuse, watered-down stereo mix, missing details like Paul's scatting at the end of the "Pepper" reprise. The mono version was the one the Beatles, Martin, and Emerick spent three weeks mixing. The stereo mix was a quickie afterthought, with none of the Beatles involved or even present"