The Denon direct drive turntables of the 1970s were not quartz locked, because that idea had not entered the mainstream back then. The alphanumeric code for those turntables is "DP" followed by a 4-digit number ranging from somewhere below 3000 to 6000. The DP6000 is the best of the bunch. When Denon introduced quartz locking of speed, they introduced a whole new line of turntables, which models used a 2-digit number following the DP designation. There are lots of those, starting I think with the DP47 at the bottom end and on up to the DP80. The DP75 is also excellent, or so it would seem, because it has the same specs as the DP80.
Simlarly, the first Technics direct drive was the SP10 and was not quartz locked. In the late 70s i think Technics may have been the first to introduce quartz locking, and that's why you have the SP10 Mk2, which looks outwardly exactly like the SP10, except the Mk2 has an outboard power supply. (Now someone will tell me Technics was not first to do quartz lock; that's OK.)
Simlarly, the first Technics direct drive was the SP10 and was not quartz locked. In the late 70s i think Technics may have been the first to introduce quartz locking, and that's why you have the SP10 Mk2, which looks outwardly exactly like the SP10, except the Mk2 has an outboard power supply. (Now someone will tell me Technics was not first to do quartz lock; that's OK.)