Is budget not a concern?
I thought you could buy two JBL's for each LMSR:huh: Not sure but driver against driver the TC LMSR will win. It can take twice the power. But if you have two JBL's they will easily beat out the LMSR with less watts. 1850 for the LMSR verse 1500 for the JBL
That being said I am not sure which is "BEST," because I dont know your application. For me I would go with multiple sealed subs but that is best for me because I like extension down to single digits.
ARE you after extension to 10hz or 20-110hz?
The JBL models in a bigger box than the LMS-R, 5 cu ft compared to 4 cu ft for the LMS-R. They both model better than the Q15 and the SSD with the same input power off 1000 watts. But having said that the FI drivers are in 2 cu ft boxes. You could buy a 18" FI SSD and put that in a 5 cu ft box which will have the same spl as the JBL and LMS-R but the LMS-R is probably a better driver than the FI's but then it is almost twice the price off a single 18" SSD. Two 18" SSD subs will defo win over a single LMS-R and that is roughly for the same money.
What is your budget for this?
I would go with the JBL's. I'm working on three 15" GTI MKI's, two in a dual opposed box and one in a sealed box with 2,400W or 800W per driver. I'm only using 2.35cf per driver but since I'm fully stuffing the boxes, it should be closer to 3cf per driver. I plan to start a build thread when I get my new speakers, hopefully, in the next couple of weeks.
The JBL's will do the best out of all your other options in the mid-bass (50hz and up). Their very low inductance and sophisticated motor will produce very low distortion and a very clean bass with a crossover above 100hz. You can get two of them for less tham $600 at Ebay. A Behringer EP4000 should provide around 800W per driver on each channel at 3ohm which is perfect for the JBL's. All for under $1,000, leaving you enough money for the enclosures and a EQ unit. The LMS-R are also a good choice but is going to be a lot more money. The drivers are quite a bit more and they'll need an amp per driver. Also, they will excel in the low bass (below 30hz) with their extra xmax but your priority is above 20hz, negating some of the LMS-R's advantage. Just my two cents.