I just finished reading Beatles '66 by Steve Turner.
Organized into chapters for each month of 1966, the book is a detailed tour through the Beatles' comings-and-goings during a year in which they covered tremendous creative ground. If you like learning about what makes your favorite artists tick, check this book out. It's thoroughly researched, but never pedantic.
One of my favorite anecdotes is when Turner explains the shift in Paul's bass sound during the Revolver sessions. It's well known that he switched to a Rickenbacker from his famous Hofner just before this in the fall of '65 while recording Rubber Soul, but what I didn't know until I read Beatles '66 is that one of the keys to his fat bass sound on the later records was also due to some clever studio hacking. Turner explains that George Martin had one of his engineers wire a speaker cone backwards and use it as a mic.
Most people don't know that microphones and speakers are one-in-the-same, it's just a matter of whether you want the sound to coming in or going out. While I knew this was possible and had even used cheap headphones as microphones back in high school, I had never thought to use this trick in just this way.
By using a large speaker cone as a bass mic, you get more surface area to capture the larger wave forms coming from the bass amp. Genius! Yet another Beatles innovation made possible via George Martin's technical imagination.
Paul's bass tone—not just his playing—is peerless on the later Beatles albums, starting with Revolver. "Taxman" kicks that album off with one the best bass lines he ever put on tape, and his new fat tone cuts right through the chorus like a lead guitar. It was clear something had changed with his playing. Now I know the recipe.
— Lee McAlilly
Listen to Turner's Beatles '66 Jukeboxes on Spotify