The Let It Be Mystery
Over the last years there have been a few very informative books available, that list all of the available outtakes of The Beatles (see here for the titles, if you don't know, which books I mean).
But in my oppinion, there is one track, that has been ignored by the authors. It's a mix of "Let It Be", that is found on the disc "Unsurpassed Masters Vol. 6", released in 1991 by Yellow Dog Records.
Of course this could be a forgery, as some have assumed, but I don't quite agree.
I don't have much knowledge about the technical possibilities to change a recording.
I have taken the time to examine the song closer and I think this has to be a real alternate mix. Here are some things I found out (SV = officially released Single version, UM6 = version on "Unsurpassed Masters 6"):
These are my examinations. As I wrote above, I don't know much about recording technique and how to change an existing recording. But is it really possible to place instruments at different places in the stereo without the master tape? My guess is that it COULD be Stereo Remix 1 from Take 30, made at Jan. 4, 1970. Mark Lewissohn mentions in the "The Complete Beatles Recording Sessions" book that SR 2 was taken for the single version. But what is the source for this alternate version? "The Recording Sessions"-book doesn't mention that acetates of both mixes were made, but who knows...?