Fatmarley
"It appears my intelligence circuits have melted"
I wasn't saying that the number of crossover parts was the problem. I was saying that narrow notch filters can be problematic. This is because drive unit parameters have quite wide tolerances and they change a lot with temperature and voice coil position/excursion.
I know that temperature can influence low frequency performance, but It's not something I've really looked into because every speaker is affected by temperature and I've never seen it as a problem. A vented voice coil and possibly a large magnet to draw away the heat seem to help, but this is in my very limited experiments. I always measure the thiele/small parameters with a warmed up, run in driver, and I assume that's what other good speaker designers would do. I don't think temperature affects notch filters because they are generally used in the mid to high frequencies. If they do affect notch filters, I can't say I've noticed subjectively.
One of the most lively and enjoyable speakers I've built had this crossover. Ignore below 300hz in the frequency response graph.
Eminence Deltalite 2510 (10" midbass) and 18Sound NSD1095N / XT1086 Horn