I’ve written about this before, but in the early 70s I was a keyboard player in a band with a bass player that used two Acoustic 360/361s. The sound was woofy but didn’t go low and it was very difficult to get a good stage balance or a decent mix with them. We played at an outdoor festival with another band whose bass player bought one of the first SVTs. The difference in sound, punch, clarity and transients were incredible. I’m not an SVT fan, but the idea of using multiple small drivers (lots of cone area) in a direct radiator design produces a much better more usable sound. When you power it with a big tube amp, the results were impressive. That’s one take on why the SVT is still around and the Acoustic 360 / 370 series isn’t.