Bass traps/room treatments

Any chance of repositioning the speakers parallel to the high ceiling short wall and your listening position more toward the 8 ft high short wall. The room appears to offer a very interesting listening enviroment but I think your current layout is not making optimal use of it. With a more symmetric layout (so that the ceiling height above each speaker is the same)you should get more consistent bass response with the speakers.

Ok, so you have the speakers along the longer 25' wall, making you sit the short distance? I believe this is how Dunlavy recommends. And, from my experience, this should sound better overall with this arrangement (all things balanced and considered of course). However, if I read you right, sounds like, yes, one speaker is in a different acoustic space form floor to ceiling...This is a tough one, and certainly not symetrical in the bass modes from floor to ceiling, between the two speakers balance wise! However, overall, your still going to get much better sound throughout, keeping the speakers on the long wall...no, I wouldn't put em on the short wall in your room!...it'll bring too much constriction and blurring, not to mention much much added coloration and reflection challenges from the side walls that way.
So, what to do...Yes, I think much of your challenge in the bass is the different ceiling heights above your speakers! The bass response will be inherently different, do to the different dimmensions of boundaries the speakers are in. I think you should experiment around with different speaker possitions a bit. Perhaps measure, with bass test tones, with a sound level meter to see which speaker is the flatest and most balanced over all in the possition there currently in. Then, try moving the speaker that seems to be off more in balance, until it balances better with the other speaker!...YOu should then be getting better bass response overall! I think you'll be adressing a bigger fundamental issue with your system, than simply adding bass traps. Yes, I'd still think you'll most likely get some good worthwile improvements, and would recommend you giving the corners some treatment...but not after dealing with the single most important aspect of your sytem set-up...speaker location (and seating location)! Good luck

I have sloped ceilings in my room, too (my forehead is also sloped, so be careful), so I know they are a mixed blessing. I also use a long wall set up and I have recently added some ASC products. But before I did that, I spent a year adjusting speaker placement, and I agree with Fliceswater that you should work on placement first. The SC-IVA is a bear to move, I'm sure, but as tall as they are, and as different as the two sides of the room are, placement will be critical. My room has slopes on the long front wall and on one of the side walls, both from 8' to 13, with a flat ceiling from there. I had some bass problems, but the biggest issue was image wander and balance. I have ended up with the one speaker about an inch farther out in the room, and I sit in the near field and slightly off center. This works better than using the balance control, where I could never make a fine-enough adjustment to get a solid, consistent center fill. I suggest that you try moving your speakers well away from the corners and the front wall, point them almost straight ahead, and sit close to the rear wall. As you probably know, the word is with the IV-A that you should not sit in the near field or you won't get good integration, but I would start too close and back them off until you start getting too much reinforcement from the front wall. The speaker with more air around it will sound farther away, and that one should be pulled a little closer to the listening position. In my room, the speakers are fairly close together and far from the walls, and the soundstage goes way out beyond the speaker locations. You might also try moving the speakers off center, away from the low end of the room. This may be a cure worse than the disease, creating a sidewall imbalance, but you must get a ton of ceiling bounce from a 7' speaker in a 8' space! Once you've gone through all of that, try adding some tube traps. ASC's customer service is great and their products are worth a try, but there are no shortcuts with funky room acoustics. Also lookup the Audio Physic website and Micheal Fremer's review of the Physic in Stereophile, where the long wall set up is discussed at length. Let us know how it goes.

Thanks for the excellent feedback. commenting further, I have been experimenting with speaker placement for a really long time...about a year now, what a painful process, but I believe I have found the best possible position (yes, I've made compromises somewhat...the speakers sound better further from the back wall, but then I can't exit my room cause the speakers are in front of my doorway! my speakers aren't "nearfield monitors" and in the middle of my room, they are pushed as close to the rear wall as possible without sounding boomy), and as far wide as possible (without pesky side reflections...I have drapes over the window there to absorb reflections)...this has achieved the best balance...I think I just need some acoustic supplementing to further balance/tune the room (I don't have a dedicated listening room, and the short wall option is unfeasable because of doors/entrances to room) I have the frt of the speakers about 31/2-4'from the back wall and 1.5' from the side wall...I sit about 10-11 ft from the speakers...the speakers are toed out substantially (the DAL manual suggests pointing the speaker directly at you...bad idea...major room nodes. If you sat a couple feet off center, the speaker is then pointed directly at you). I've been draping/hanging some fabric from an upholstery store from the high points of my ceiling down to over the speakers...this has made a substantial difference in sucking up reflections, and improving the bass response, so I think further experimentation is necessary there.....the ceiling height does seem to be awefully important! thanks Whknopp, I really need to think about not always treating the room symmetrically..I will experiment with that. To further describe the acoustics of my room, If I sit on my 3person wide couch on the left side, I can hear the right speaker and I still get a decent stereo image. If I sit on the right side of the couch(the low ceiling side), I can't even hear the left speaker and it sounds totally off balance)...well...looks like more trial and error...

I agree with Stevem's post above on ASC products. I use both their tube traps and panels with excellent results-- expensive, but worth it. Good Luck. Craig