Using tube traps requires extreme patience. I have had them since 1988, and having the seams pointed towards the speakers will usually yield quite good results. HOWEVER, the seams will sometimes need to be slightly oblique and they must be moved in 1/64" increments (or less). Additionally, you must move them along the walls -- both sides and rear -- in miniscule increments, so small you can carely tell you moved them.
On side walls behind the speakers, Moncrieff suggested orienting the seams towards the speakers. Forward of the speakers, he suggested pointing the seams towards the speakers. This must be done over a period of weeks. One should move them one at a time. I have around 40 or so, stacked floor to ceiling. If you have jogs in the room, you MUST have traps in those jogs, or the upper bass/lower midrange will sound thickened. When I had an addition built onto the house, there was a jog, so the room narrowed from 13' to 12'8" and I heard the thickening, but it wasn't until a couple of years ago -- 5 years AFTER the addition -- that I looked at the jog and thought, "Hmmm...sound COULD be building up there, too." I put 2 traps in there (8' height) and the thickness disappeared.
It is crucial you move them exceedingly small increments in whatever direction you move them. Forget 1/8" as "exceedingly small." I mean small enough that you can barely see that you moved them. Tiresome? Yes. But the amount of spatial detail, low level detail, transient info, room size, image focus and an actual sense of how instruments sound in a real room will leave no doubt. You must also, when you think you have them moved in exactly the right spot, then move them BACKWARDS a tiny fraction. You will either find high frequency (i.e., bells, triangles, harp) transients better or worse. At that point, either move them back to where they were or leave them.
Seamson traps directly to the side of you are generally best (on cones) pointed at 45 degree angles INTO the room, but again, they require extremely small turns.
I also have the ASC's room damp setup with resilient channels. In this setup, no walls touch each other, not even on the floor, so there is no connection. An adhesive is used to seal cracks between foor and side walls and ceilings.
There's an article on ASC's site by Moncrieff back in 1989.
