[QuadList] AMPEX Mark Ten 5 mil head

[Dale Lamm]

[snip]

Back in the day, I saw very few 7 1/2 ips recordings that were not low
band...but of course, most of my quad experience back then was in
educational television.

[end]

First time I saw 7.5 IPS in use was in the late 70's at a cable company head 
end. HBC on a TR-600, might have been Warner Brothers ownership. The 
operator said they could get an entire feature movie on a "90 minute" roll 
of tape. Since there was just one TR-600, reel changes would have been a 
problem.