Metallica incorporated a lot of different sounds into their Master Of Puppets album, with lots of variation among the songs. In a Songfacts interview with Flemming Rasmussen
, who was the engineer and co-producer, he explained: "We used six mics for each guitar, so we had a full stereo setup. For the first rhythm sound, we would record that in stereo - that would be the main thing. And then we would start mixing them to a mono track - that's when we started doubling. Because again, in this day and age, you would just do more tracks, but we were limited to 24 tracks times two, because we had synchronizers. I would change that constantly to suit the song. I would combine any of these in the way that I thought the song should sound."