Seating distance to Magnepan 3.6r's?


I'm moving from my current living conditions to a new apartment. The main room (living room and listening room) is 17 feet wide by 26 feet long with 10 foot ceilings. My questions is: the Maggie's will be approximately 4 to 5 feet from the front wall, what is a proper listening distance, how far back should one's listening chair be?
Thanks for all your comments.
zippyy
Thanks Jafo100.
Since my room is 26.5 feet long, I hope I don't have to end up with the speakers 9 feet out into the room. Sogood51 thinks it will end more like 6 plus feet according to Cardas. We'll play around and see what happens. Thank you for your insight as well.
I like both the Cardas and the rule of thirds (if you have room) for Maggies. Typically you would create an equilateral triangle between your chair and two speakers for a listening position.

BTW you have a near perfect room size based on a (very old) article in TAS - they mentioned 16 x 26 x 10 as perfect for hi fi in general.
Think of placement this way.....The Maggies send sound waves in both directions forward and backward...what you are seeking is the blending of the two....just as if there was a piano or a quartet in your room....they don't go against the wall....and they don't go in the center....I have found that for some reason...and I cannot tell you why...a distance of 12 inch multiples off the back wall works great for the Tympani 1Ds as well as the 20.1s...

As for the side walls...I have never had a rule to follow other than a triangulation as mentioned in one of your responses...good luck.
The rear sound wave should be delayed from the front sound wave...not blended. You need at least 10 milliseconds of delay....(so, at least 5ft. out).

The 1/3 rule, should be called the 1/3-1/4 rule. As you move the speakers between these two grid points...bass will increase, and decrease. The speakers bass will sound best, at...or, somewhere between these two grid points.

Dave
Philjolet, It's too bad I have to share this room as a living room, otherwise I'd turn it into a dedicated room. A room this size in Los Angeles is a true luxury.
Thanks Jafo, I'll try 12 inch increments like you suggested.
Sogood51, Won't 25% out in the room create MORE bass then 33% out in the room? Since it is not a dedicated room, the distance probably will never get out to 8 or 9 feet. But I will definitely try It to hear how it sounds compared to 4 to 5 feet.
Thanks again for all your input.