Well, in the old days (the 1950's and '60's) all there was to mix on to was 1/4" 15 ips tape, either mono full track or two-track. In the 1970's, some studios went to 30 ips to get a better signal to noise to avoid having to use the dreaded Dolby A. After that, some machines were modded to use wider 1/2" tape (normally used for three or four track recording) for even more signal on to the tape. Problem is, the faster the speed, the worse the bass response suffers. So, for me, a good mix tape situation would be 15 ips 1/2" tape, non-Dolby. Note that most of the music that we talk about endlessly here was mixed on 1/4" non-Dolby analog tape running at 15 ips. Sounds wonderful that way, yes?