Why Mix the Instruments on to just one track?

[harrisonjon]

Considering how sophisticated Brian's arrangements became by 1965, wasn't there an option to use more than one track for the non-vocal parts?

[Loaf]

Brian was working with 4 track studios. 1 track for instruments. 2 for vox, one for further instrumental overdubs. He could have gone with 3 for instruments and one for vocals. His choice.

[Cliff1000uk]

I think it was the fact that up until '66, all the studios Brian was using only had 4 track recorders.

I'm sure someone with better knowledge will correct me on alot of this but my perception is that basic instrumentals got recorded on 3 maybe 4 tracks and mixed onto one track. The three remaining tracks on this tape were used for backing vocals and overdubs. These were mixed down too and so the remaining 2 tracks were used for double tracked lead

Again, I could be miles off but the main reason is that Brian only had 4 tracks at his disposal until Columbia or Wally Heider got the first 8-track recorders.

[Joshilyn Hoisington]

Also, remember that Brian dug the mono sound, so even if he had recorded comps on 1000s of tracks, he would still have combined them (and the vocals) down to mono in the end.

[Andrew G. Doe]

Brian was still using a 3-track machine as late as 1965.