Hal was aalso responsible for two big changes affecting all drummers playing studio gigs during the 60s /70s period. One was the low tuning of tom tom heads to prouduce that flabby "boing" sound that every producer insisten upon ( regardless of who was playing the date ) The second thing was a large set of rack (or rail ) mounted single headed tom toms ( usually a set of 6 to 8 ) ranging from very small to quite large that Hal designed . Pretty soon ( much to the delight of the drum manufacturers ), the octa -tom sets were also an investment most studio drummers of the era had to spring for.