"I've been playing with the Chesky test CD's (Best of Chesky Jazz #2, "Height Test" and "General Image and Resolution Test") and I can't get the height to extend beyond 65% up and the imaging doesn't go all around me on that monkey test (if you know that track). I wonder if this has anything to do with lack of sidewalls."
This is a good CD. I have all three volumes and they are great for testing the imaging of your speakers. For the height test, that one is really difficult for a speaker to image properly. As they say in the CD, it's more of a test of whether the microphone can capture that height information than the speakers. Having said that, my system does a decent job of it. I think this test also exposes the weaknesses of speakers with the tweeters way above ear level, like the YG Acoustic Anats. There's simply no way a speaker like that can accurately portray height information with its drivers aligned like that. I listened to that speaker recently, not using this disc, but with the Sheffield Drum Record. While the imaging was very holographic and quite convincing, hearing the high-hat 6 feet above ground was a bit disconcerting and by no means "accurate".
I think this track would be a good test for someone using front height channels on Audyssey DSX or one of those formats. Very possibly you could get very realistic height imaging using the matrixed height channels.
The "General Image and Resolution Test" is great too. I love how the tribal sounds come right at you until it sounds like they are right beside you. In my set-up, I can hear the shakers right beside my ears, and slightly behind it as well. I had to double-check I didn't have the Dolby PL IIz on in my pre/pro. It literally sounded like it was coming from my surround speakers.
If that's not working in your set-up, it could be the lack of sidewalls, but there shouldn't be that much reflection off the sides of a well treated room anyway. How toed in are your speakers? If the drivers are pointed right at you, that may be part of the problem. The most I would toe in speakers (if using a triangle set-up) is 15 degrees max. A good pair shouldn't need that much for pinpoint imaging.
From what you write, sounds like you have one of those Asian-style apartments with no walls between your living room, dining room, study, etc. While technically it is all "one" room, it's probably advisable to only treat the area that you are listening in as the "room". In that case, what are the dimensions of the listening portion of your "room". Also, when you say it's in a trapezoid shape, do you mean the walls don't meet at a 90 degree angle? Depending on the angles of the walls and how well your room is treated, there could have a major effect on the imaging, which may not be all negative. Are you using any acoustic panels or bass traps, etc.?
I don't see why you couldn't get the full wrap-around effect on the "General Image and Resolution Test" even in your situation, granted your speakers are capable, once you've figured out the ideal speaker placement in your room. The cool thing is its fun to experiment!
