And although Martin and Abbey Road engineers such as Goeff Emerick did an amazing job at the time, this process also resulted in some parts not being heard very well, or parts originally recorded in stereo coming out in mono. This accounts for some of the quirkiness of the Beatles' recordings. The technology now exists to synchronize all those individual parts on that were on separate tapes, something which could not be done in 30 years ago. So it would no longer be necessary to use those partial mono mixes. And in potentially the biggest sacrilege to Beatles purists, Cobbin did not try to re-create the original mixes exactly.
Some tracks are quite close to the originals, while others are significantly altered.
Perhaps the most obvious difference to the casual listener, is that Cobbin dispensed with the quirky stereo panning that had some of the vocals on one side only. On almost all the new mixes, the vocals are placed squarely in the middle. But now the instrumentation is more spread out, surrounding the vocals. Going back to the those original recordings, and hearing these new mixes, one gains an appreciation of the care and sonic excellence that went into those original sessions, especially when compared to brand new recordings that sound vastly inferior. The included material dates back to about 1965 with music originally from the Rubber Soul album and on up through four songs from Sgt.