Hi
Other than the special run installation subs, like the CV subs used in movies like Midway etc, I think it was Tomlinsin Hollman’s work which lead to the THX standards that (among other things) drove the need for extended low end. Jurassic Park was the turning point in the movie industry so far as getting down if I recall.
I think the first modern widespread “standard” subwoofer for theaters was the Kintec KT-90 if I remember right. It was a 2X15 vented box, self powered and made specifically for cinema use and installed in many theaters. I remember that one as they were the same size as the TPL-2 we made at Intersonics at the time.
Prior to that when there was lf extension it was via big horn systems made by Altec, RCA, WE and others. Big cool looking and impossibly large cabinets and horns, ah and no power compression either (because the voice coils came off the former before they got that hot)
Keep in mind the technical “knowledge base” even in the 80’s said that for live sound, nothing below 80Hz was needed or desired and you can’t make real bass with a horn.
It was a great time to come up with a motor driven horn loaded woofer I’ll tell you haha.
Best,
Tom Danley