Speaker placement

Interesting. I didn't try that with my Acoustats or Quads but I did angle them so that their backwave hit the sidewall behind the speaker as opposed to the backwall. Sort of diffused the backwave as it lengthened the on axis signal path. This created substantial toe in but the axis would have crossed behind my head. Now with boxes, I toe them in so that the axis crosses in front of me so I avoid a lot of sidewall issues which were not so much a problem with the Stats or Quads. So much to consider....:-)

Do yourself a favor - put away your tape measure and listen with your heart. Check out my description of the Master Set process on myspeakersetup.com

Hifibouncer, I set up my speakers starting with the L and R spkrs near the side walls, moving each toward the middle. (from some online advice). I did not know this was the Sumiko Setup; but it worked well for me.
I just used your method of setting the rake angle and WOW, it has an incredible effect. Thanks for sharing.

ps.. I wonder why dealers never talk about using rake angle with speakers.

I have owned some multy driver cone speakers that need to be set back so that the drivers are more time aligned,like my last cone speakers the Ref 3 Grand Veena.

I tried to rake them by increasing the height of the back spikes and I liked it,but you had to sit closer to the speakers, more in a near field way.

My present speakers which were made in the 1970's are designed with a built in slant,but I prefer the sound when the speakers are raised at the back so that the top of the panels are flat using a level.Maggies are always seen with a back slant,yet my Maggie front and rear onwalls in the HT have no slant and the sound is very good.

I think there maybe some merit to the slanted back of the drivers to avoid floor bounce, but I really believe it's just a trade off as you increase ceiling bounce, which I think is worse,and not many of us want to add damping or diffusors to the ceiling, but next year I plan to do this as I devote more time effort and money into getting the room right.

Floor bounce is more easily controlled with a thick underpad and carpet,so I will side with the folks who like to rake their speakers opposite to the standard accepted practises, even when the designer intends for the drivers to be time aligned-sloped back at the treble area.I am a rebel at heart myself.

I like the more direct and to my ears ,sound of the drivers /panels firing straigh out into the room.

Experimenting with speaker and chair positions is fun, educational and doesn't cost a thing to do.

The best tweaks in life are free.

Glad things went well adjusting rake - kinda fun! I'm convinced that neither dealers nor manufacturers really focus too much on imaging, they're more concerned about tone. I went to a local Avalon dealer to hear the "Time" model, and the center vocalist sounded like he was sitting on the ground and 4 feet left of center. And the salespeople had never noticed the problem!