Some pics of old theater subwoofers, which I have demolished. 8 subs in total. Used in the late 70's early 80's for sensurround movies like earthquake. I needed to up this pics because not many have seen them in real life. Only a few who have seen the movie in the theater back then. The history of these particulary ones are used for 16 total in a theater. Stacked 8 in each corner of the lower theater standing upwards firing back into a external horn fold extension.