In the second post I linked to above, I talk a little about what makes Beatles' records distinctive. They really don't sound like anyone else. The reasons are many. There is a quote from somewhere that says that genius is nothing but infinite attention to detail. There is certainly some truth to that. The Beatles were a creative group that encompassed not only John, Paul, George and Ringo, but also included George Martin, who contributed a lot to the beginnings and endings of songs, arranged string and other instrumental parts and even played keyboards on some tracks. There were some technical and engineering people that contributed as well. The title of this post, "artificial double-tracking" refers to a technique discovered by Ken Townshend. The Beatles had discovered that if you double-tracked the lead vocal, it had much more presence. So they developed the practice of recording every lead vocal twice. This was very time-consuming so they were delighted when a way of doing this automatically was discovered. It is called "artificial double tracking" or ADT and involves duplicating a track slightly out of phase so it sounds as if two singers (actually the same singer twice) are involved.
But this is just one of many techniques they developed. Others included recording the voice at a slightly slower tape speed and playing it back at the normal speed for an intensified effect. They did the opposite with the instruments: recording them at a slightly faster tape speed and slowing down on playback for a 'fatter' sound. They recorded guitar solos and played them back backwards, they stuffed sweaters in the bass drum for a muffled effect. You name it. The purpose of all this was to find the uniquely 'right' sound for every song. For an example, let's trace the evolution of a single song, "She Said She Said" from Revolver. This is a tune by Lennon that comes from a conversation with Peter Fonda around a pool in LA. Most remarkably, we actually have Lennon's early drafts of this song that he recorded at home with just him singing and a guitar. Have a listen to how the song, especially the melody, evolves in these brief clips:
It starts out as little more than the phrase "he said" (later changed to "she said") and an up-tempo rock and roll accompaniment. But with each attempt, the melody evolves (at the beginning there was almost no melody) and the chords get less generic. Also notice the very ordinary sound of Lennon's voice. It sounds a lot like anyone fooling around at home with a tape recorder. Luckily, we even have the guitar tracks of the final version isolated. Here they are so you can hear how the guitar part evolved:
Now listen to the finished song:
The first words, "she said" are sung by Lennon alone, but with double-tracking. This is answered with harmony vocals "I know what it's like to be dead" in thirds. One nice touch is that this harmony line is immediately echoed in the guitars. Other things that were added are a contrasting section ('bridge') in 3/4 time on the words "no, no, no, you're wrong" and continuing to "everything was right". Oh, and the whole arrangement, of course.
The transformation from the simple, not very interesting, song John was messing around with at home and the finished version is simply astounding. And it all took place, according to session records, in one nine-hour session on June 21, 1966, the day before the master tape for Revolver was due to be compiled. That alone leaves me rather amazed... Anyone can walk into the studio with some lyrics on a napkin, a vague idea of a melody and some chords. But how many can end up with a song like this nine hours later?
UPDATE: I didn't mention Ringo's drumming but here, as in every song, there is no generic back beat. Just listen to the amazing variety of what he is doing and how it changes to suit what is going on in the song. Now compare it to the rather stereotyped drum patterns of most current pop songs.