Not sure of the time line but let's not forget our good buddy Rick Ramsdell for his early efforts to bring the low notes forward with his 27" sub. I think that was about 20 years ago maybe more. In talking with him he mentioned that the only large woofers at that time were kinda weak - like the EV 30 thing that only handled about 100 watts. He made that 27 to do some damage and it handled some serious watts. One of his demos was to plug a zip cord into a wall outlet connected directly to the speaker and watch it dance at 60hz without blowing! I wonder how many are still in use today?