Hey-hey!!!,
The system only has ~12 W behind it. It has no problems with high volume. I bounced the cone off the throat plate when I crossed it at ~400cps with a 1st order series cap. The horn unloaded, and excursion went up.Right now it has a 20 uF series cap as its x-over. An old PCB GE AC cap. This puts it at ~1000 cps or so. Single L in series with the 15".
The 4560 is like the Altec A-7 bass bin with a slightly smaller volume. The 12" BR boxes I brought to MD are still in action from time to time, and are distinctly diffferent from the bigger JBL's.
cheers,
Douglas