Speakers along short or long wall

Hmmm.... I'd start with the rule of thirds for both axes to get a good estimation of the total differences. Then maybe tighten up the long wall geometry to the same as the short wall one to further isolate just the ROOM difference...in other words set of a nearfield triangle and try it both directions. I use such a geometry on the short wall, creating a VERY deep sounstage (8 ft behind the speaker plane). Sidewall tuning becomes more critical, but with great speakers will yield a very wide stage, as the 60 degree or so angle with the listening chair is still sumptuous. It all depends...no easy answers here.
Just have fun, trust your ears, paying specuial attention to toe in and sidewall splatter. Some speakers--especially 3 ways or any with widely spaced drivers, will require a minimum lestener distance before cohering sufficiently.
My home demo of N803 comes to mind. They needed 10+ feet to work, as the midrange/woofer crossover is too high at 400Hz. So there's a speaker that ONLY works on the short wall in a long triangle, for example, but with special attention to sidewalls to dampen the hot tweeters' flare.
Two-ways will generally cohere well in the nearfield, giving you more room setup geometries that are acceptable tonally. As you might sense, I'm a fan of closely-matched stereo pairs in the nearfield, using a 7.5' equi triangle in a 14x24x8 room. Cheers.

Subaruguru,
I, too, am a big believer in the equalateral triangle set up. Whether you set up along the long or short wall, is dependant on the type of speaker and such things as the size of the desired soundstage prefered. I like a big soundstage at a close perspective. I also sit 8th row center at the San Francisco symphony.

I use the big B&W800's along the long wall but sit at one point of an 8.5' triangle in a 15x25x8 room. The speakers have lots of room behind and to the side.

Unfortunately a set up like this takes up the entire room, with virtually no way to use it for anything else. I am lucky my wife lets me do this in our small house.

Richard

Thanks for the input. You are confirming my thinking. I used to have them at the end of the room 6 feet from the wall with windows. 8 feet apart, but the listening position was about 15 feet away. Everyone told me put the speakers along the short wall.
I moved back today. 8 feet between speakers. 10 feet to listing position. Improvement.
Like the equilateral triangle approach.
Thanks.

Now I am ready to tweak with the Radio Shack meter.

FWIW when you're thru tweeking with the RS meter just relax and listen for a few months. By then you will have the sound stage fully absorbed in your mind. Then revisit the positioning to tweek your sound stage even more. Move speakers about, no more than an inch or so at a time (after marking the original positions so you can move them back). Great set up usually takes a long time, much experimentation, and patience. Enjoy.

I would if it was me use the short wall.But experiment, and have fun...