What method did you use to position three JL Audio subwoofers within your room?
I didn't place three JLs subs in my space/living room
Around 2013 in a rented apartment, I had the F113 that replaced a TRIAD 18" subwoofer, placed mainly in the front, initially between the speakers and then to the side, which were the only positions I could allow,
the performance improved significantly when I connected an external CROSS unit and reached high performance, But quite a few resources were taken.
The JL been replaced with a Velodyne DD18plus, which fitted in significantly better.
When we moved to the new house about 9 years ago, The Velodyne was less integrated than I expected,
I decided to test JL again this time in the configuration of a pair of F110 subwoofers, I worked a lot with ANTHEM and their RC Setup, then I also integrated a DIRAC 88a as an external unit, after countless attempts and tests, the best result I had was when One subwoofer is diagonally towards me and the other is on the other side further forward, unfortunately my wife didn't liked the preferred locations,
I moved on, and brought countless subwoofers, (smaller velodyne dd15, SVS's, B&Ws and more) the ones I liked more (for me) were REL.
worth to mention that i also very like the Wilson Audio Active Watch-dog 1 & 2.
Today, I spend 10% watching movies and any time I have in front of the SETUP I spend with 2ch music,
that's why I invested significantly there
(I gave up expensive processors, center's and subwoofers, after I had them and ran back to 2ch music without all those artificial aids and invested significantly more in two channels).