Two JL F212s verses two Velodyne 18 plus?

Drummermitchell, I thought you went with 3 or 4 of the JL Audio F113's? I personally demoed the JL's and Velo's and came away with 2 F113's. Both are great subs and if anything I just felt that the JL's were a bit faster overall. For HT demo we did some gunshots ( Matrix) which really shined on the JL's. For music DD18's went a bit lower but overall musicality I still thought the JL's were better. Gotham 213's are in a differnt league over the 1812's. F212's were not present but I would guess that two F212's would be much better than two DD18's.

I went with four JL's(113's)two for music and two for HT.
they were a big upgrade compared to the DD-15's I had.
When I got to hear the 1812 in a big room I was shocked how good she sounded.
I thought,no way could I get this sound in my room.
To my total surprise and amazement,the 1812 gave me that sound
I've been looking for,superb midbass punch and she digs real deep.
I FORGOT ONE IMPORTANT THING:THE ROOM(s)
thinking I was loading 228sqft(listening area)I tried everything with the JL's,no go.
What I didn't realize is there is a room to the right,small hallway,stairwell and to other rooms.
In reality the Jl's were trying to load around 1240-1300sqft.
The 1812 gives me all the musicality and HT thrills I could want,plus the lifetime warranty the dealer gave me.
I'm sure Gotham twoX213's would load that size of room.
I got a great deal on the 1812 and it was the sound I get out of her that sold me.
Couldn't audition the Gotham's here as I had bought the F-113's on here.
Totally satisfied with the bottom end now,took a few subs to get here though.

I have two F113's that fill a 18x30x10 room that opens into a dining room and office/den that is about the same size. I could not imagine needing to add anymore. For example in the movie Monster's Inc when the giant bird crosses the street, it actually feels as if the bird walks right by the couch and then behind you. When it takes the fist step I feel as if the couch is raising off the floor. I use this Movie scene and a few scenes from U-571 to show friends what these subs a capable of and always get the WOW factor out of them. The strength of the JL's are speed, acurracy and flat out image like crazy. Two F212's would just add that much more excitement and possibly be a little more musical.

Perhaps as all exterior walls are concrete has something to do
with it,or perhaps those subs were partialy defective(don't know)I use to have them up at 2-3:00 on the dial after using the ARO,plus even placing them where I sat and then put them where they sounded best(all a no go).
I hear guys having there JL's at 9:00 or perhaps a bit higher.
Anyway the Velo hits me where it sounds and feels great,
so I'm good,music is such a joy now with this sub.

I think 2 F113s is more than enough for your room.