Maybe I should start a new thread, but let me state that I bought two Danley THmini15s.
At 100 lbs each, they're unsurpassed in the paperweight category. They don't go as low as 18" subs, but these ought to go a lot louder than my current subs.
Danley turned me on to a whole new way of measuring power. You guys have probably known this forever. Anyway, I got a wave generator app for my phone. Set it for a 60 HZ sine wave. Set channel trim for unity. Pushed fader to unity. Pushed sub feed fader to unity. Selected 200VAC range on the meter. Set Crown XTi6k Ch 1 to -3 dB limiting to achieve +-70 volts at the speaker outputs.
Set Ch 2 at -6 dB limiting (50 volts) for the old pair of 18"s.
I've got the 24dB slope crossover set for 50 to 110. I may experiment with that.
I've upgraded my tops to Yamaha DSR 115s. I think this is going to be a really nice system
Anyway, I know I got 99% recommendations to buy powered subs, but I couldn't get it out of my head that passive was viable, and these 15s are pretty cool. Very limited testing indicates that the 15s don't go as low as my 18s, but the 15s are quite relaxed at levels where my 18s are fighting for their life. The 15s strike me as very "hi fi".
As Ivan touches on in his post (I'm editing this to add a few points), SPACE is my limiting factor. I have a very small 4x6 trailer, and these 15s are going to make packing so much easier. With the 18s, it really came down to less than 1/2" whether the door/ramp was going to shut. I'll be able to make better weight distribution as well. I could never find a powered 18 with the right footprint.
More to come following my first outdoor gig 6/17. Just checked the calendar, and I've got five outdoor gigs this month.