Listening triangle

Really does seem to be a lot of trial an error in speaker placement as each room is so different.
I tried the Cardas method and it was different, but the soundstage was not as wide (it called for moving the monitors 4.25' from the sidewalls and 7' from backwall).
I am using a variation of it and the rule of 3rds, or 5ths or something :)

A couple basic suggestions:

Move the monitors into the room from the backwall if you can, and in from the sidewalls. Experiment from there on placement and toe in.

I settled on 5' in, 3.25' from sides, 8' apart and my listening spot is 10' from monitors (so not a triangle). Sub is behind the left speaker away from the backwall and next to the sidewall.
No toe in. Room is 15.5' wide by 26' long and 8' high with stairwell wall on right side halfway into room.

System is in my signature.
Have fun. It took me a week of playing around.
Will probably change it next month:)

Oops. Should have said my 8'X 10' X 10' triangle was not a triangle with equal sides.
I did read somewhere where this was suggested as possibly desirable, but that was just a theory.

I've always had luck following the advice that said to make your listening distance the same as the speaker width. This is not an equilateral triangle, rather, a perpindicular line straight back from the center point of your speakers. Example: say your speakers are 8 feet apart, you should be 8 feet away from the center point of your two speakers, kind of like a big T-square. If your speakers are 10 feet apart, your listening poition should be 10 feet straight back from the center of your two speakers, etc. Try it out and see if it works. Regarding toe in, I'm sure it is speaker dependent, I have mine so I can see only about 1" of the inside of the speaker, kind of like they're ointing at my shoulders.

Am I the only one that uses an equalateral setup. Same distance from each speaker? It works best for me in small rooms anyway. 8' is ideal depending on the room size.

I agree that every room is different and you must experiment. Your lack of a second boundary wall means a non symetrical arrangement, which is more challenging. That being said, here are guidelines that have worked for me.

In a large room such as yours, start by placing the speakers on the narrow wall, using Cardas for a starting distance off the existing side wall (distance to side wall is 0.276 X room width). With only one actual wall, you may discover image centering issues and a sound stage that is wider on one side. On the positive side, you might discover some pleasing echoes up towards the ceiling corners.

Place the speakers a minimum of 2 ft. off the back wall with no toe in. Sit slightly further from each speaker than they are apart (if 8 ft. apart, sit 9 ft. from each measured along the triangle). That makes the included angle more like 55 deg. than 60 deg).

Experiment with moving the speakers closer together or farther apart and observe the image. The further apart without getting to close to the side wall, the better, as long as the image holds together. Many speakers will go up to 10 ft., no problem.

Then, try moving the speaker and listening position (together) further from the back wall, making measurements at the listening position. Avoid having the side and rear wall distances close to the same. Look for the best low end response.

Finally, experiment with toe in to minimize side wall reflections and control high end brightness. For well balanced high end speakers, the less toe in the better.

The variables in the setup process are many and the number of combinatins are infinite. But, don't be discouraged, if you are patient, it will come together. I am still making adjustments after 2 years, based on a better understanding of what is going on. Take good notes of the trends. They can be useful later on.

BTW, a DSP/RTA beats the heck out of a RS meter for speed of taking and analyzing room measurements. You can get a good one with calibrated mike under $500.

Have fun and let us know how it goes.