Unless one has a lot more THD then the other one I don't think you would hear a difference, until they are truly pushed to there max.I noticed no difference between the two. I never pushed to the breaking point but at 116dbs they sounded the same . the uxl in a small ported cab crushes the si18.
fwiw, 12 cubes at 16hz 1 watt um18 (dark grn) vs. uxl18. (upper end inductance effects will probably bring down spl a bit).
Over a year ago I did compression tests between the SI18 vs FTW21 to see what I'd get as results.
Don't forget I own both...
There's no 3DB difference between the FTW21 and SI18...in fact the SI18's performed extremely well against to the FTW21's.
And this is with almost HALF the power being sent to the SI18's
Red 2x FTW21's one per corner 2100Watts per sub
Blue 2x SI18's one per corner on top of the 21's 1250Watts per sub.
Mic starting clipping @117DB
Results: (Forget about the green graph)
So cheating out and using the 4cube PE cab on these is just leaving too much on the table, heh?
It's alright.Reading comprehension fail on my part. Correct.
What amp are you going to use? You could run both channels of an NU6000 to that one box. Can't bridge that amp, so you'd have to use a four-conductor cable, and wouldn't need to wire the UM18s to each other, just to a four-pole speakon connector.
Josh should contact us via the Dayton Audio web site if he is still interested in reviewing a driver. We're easy to find.