Speaker position????

I used the simple Cardas placement formula. I can post the website when I get home. It involves the "Golden Ratio" known from the times of ancient Greece...
(sqrt(5) - 1)/2 = 1.618 and its inverse 0.618.

If you can find a simple solution, patent it before you tell anyone. The correct location is dependent not only on the size of the room, type of furnishings, type of speakers, but also what your priorities are regarding sound and furniture location. Even designing a room from scratch where you have freedom of choice ain't a walk in the park. And it give you something to on a rainy day. :-)

I started with the 1/3 rule and went from there.
speakers 1/3 in from front wall--- listening position 1/3 in from back wall (behind chair)
Speaker seperated aprox same distance as from listening postion to create a tringle. Then adjust slightly as needed.
good luck