X1 orientation

There's always the 184 sub, close to the X1 response but tall rather than wide..

To be fair, I haven't heard the 184 yet, but when pondering building one before I found a few rave reviews on a dubstep forum.
The response says it plays higher than the X1, so I'd assume it sacrifices some SPL for bandwidth??
Backlash, I think, had some 184s. Would be a good person to ask the question of...

I was taking the same approach as you, I wanted X1s (because they're brutal!) but wanted them tall rather than wide. I took the chamber volumes and port tunings and redesigned it to be tall (thread about it somewhere). Didn't work out unfortunately, no subbass whatsoever, just tons and tons of 60-70hz!

That was my concern too, the 184 plays a larger bandwidth. I would much prefer to have the higher spl to keep up with the rest of the rig. whats the ms-18s? mini staipier sccop?

If I am lucky enough to pick up another pair of F1b's then like ceharden said I could then stack them properly.

I'm going to take the plunge....watch this space!

Thanks for the info guys. 

Surely while you were re-furbing the F1B's you got your tape measure out.  Can't that difficult to build another pair?

X1 is a dual bandpass box. To be certain you will be happy with such a choice depends on driver selection for the required parameters/use.

Are there any X1 owners in the Gloucestershire/Wiltshire area that would be willing to hire me a pair for an evening? Preferably with your goodselves as well to show me exactly how good they can sound? all expenses obviously covered and a supply of coffee or beer will be available!