Originally Posted by
botley
To get a loop to vamp in a musically sensible way, precisely to the width of the record? No way! That is insanely difficult, I asked a cutting engineer here in town about it (Noah Mintz of the Lacquer Channel mastering facility). I know that Coil and bands like that in the past have put locked grooves in the middle of their records, weird shit like that to deliberately fuck with the listener and subvert musical expectations, but if you want to achieve that specific effect (a one-measure guitar pattern looping constantly at the end of a song), it may take dozens of tries to cut it right AND you also have to start over and re-cut the entire side each time you make a mistake.
When they re-mastered the Beatles' Sgt. Pepper album for vinyl a couple of years ago, the mastering engineers at Abbey Road Studios had to take several tries to re-make the nonsense chatter locked groove at the end of the album just so it was the same as people remember it being from the original... and that's not even a traditional musical phrase length, it's just gibberish voices for a couple of seconds.