how far off the wall

Here is a link to Cardas' room setup, if you look down toward the bottom of the page, there is info on setup of a dipole speaker. There is also info on speaker placement on the Rives Audio website.

When I owned the ML SL3's they were out a good 5 feet or so from the wall to the front of the panel. However, I also had heavy drapes hung on the wall behind the speakers as well.

Cardas Speaker Placement Link

If possible, put your panels at least five feet out from the wall. The reason is, reflections delayed by more than 10 milliseconds are less detrimental to imaging than earlier-arriving ones. However, ten milliseconds (roughly corresponding to a ten foot round trip) isn't a hard threshold - rather, merely a point along a continuum.

Personally I much prefer diffusion of the backwave rather than absorption, though if the room is very bright absorption might make more sense. But the backwave is adding to the reverberant energy, making the presentation more rich and lush and lively all at the same time. Seems a shame to just absorb it. Diffusion of the first reflection zones (fake ficus trees for instance) preserve that reverberant energy but keep it from generating image-shifting strong, distinct early reflections.

If all you can get is two feet off the wall, then diffusing the backwave energy is even more important.

If you have free reign in your sound room, you might try a diagonal or semi-diagonal configuration. I've found this to work well in situations where dipoles have to be placed very close to the wall.

Best of luck to you!

Duke

Go to the Martin Logan Club for more info.

http://www.martinloganowners.com/~tdacquis/forum/index.php?

Duke and Audiofankj thank you for the words of wisdom and the website I foud booth very helpfull.cj

Besides saying 5' off a wall tehre is a formula out there to help avoid standing waves and all sort of issues that place your speakers based on room size. The speaker in general should be measured from the middle of the cone not the enclosure.

To tell you a story though I had a really good guy came in and tune my room. He started by the book placement, then tewwkwd to his sound meter and in the end did slight tweeks based on ear.

Far enough out to reduce the chances of non-modal peaks and nulls being introduced...modal peaks and nulls are another story and problem...although the two tie together overall.

Non-modal peaks and nulls are caused by a freq's wavelength and in relation to it's distance from room boundaries. Bass wavelengths are very long so reach all walls within the room.

Odd points: 1/4-3/4-5/4...ect,ect cause nulls
Even points: 2/4-4/4-6/4...ect, ect cause peaks

As you move the speaker out...and away from the wall you will pass through these wavelength points. The important part for bass in many rooms is usually to get out past the first 1/4 wavelength (null) but maybe not into the 2/4 wavelength (peak)...somewere in between these two first measurement points may be fine also.

If we use 100hz as an example:

2 ft 10 inches is the 1/4 wavelength for that freq...null

5 ft 8 inches is the 2/4 wavelength for that freq...peak

Of course all the other bass freq's have a different wavelength so have different measurement points in relation to the wall for their peaks and nulls.

5 feet (or so) works so well because it's far enough away to clear the first null for almost all of the lower bass points.

These same problems effect the listening position in relation to room boundaries...I'm sure you have read at this or other forums advice for placing a subwoofer at the listening position while you crawl around the room listening for the best bass...and then swapping those points between yourself and the sub.

I'm not the best at explaining things... even a worse writer, so sorry if this is somewhat unclear.

Dave

Duke - I am currently researching diffusion options for some planar speakers I currently have 4' from the wall (Quad 988's). There are cheap diffusor options (Auralex), but the reasonably priced ones are either limited in depth (2-3 inches) or complexity (and randomness) of form. Then there are the more expensive RPG and Auralex forms, but that will cost a bunch to cover maybe 3'x5' behind the Quads. Do you have any recommendations for diffusor options?

Thanks, Peter S.

Sogood51, my head is about to explode. No i did not know to crawl around the room listening for the best bass. Could you our one of the members here suggest a entry level book on audio setup. thanks so much

Im so glad Im not using logans anymore. Never could find the perfect position, I was always moving them around because one area or the other suffered everytime they were moved. They are great speakers however, its just nice to just have to adjust at initial setup and be happy, like with my focus 20/20's.Its amazing how ever new logan owner battles with this issue.

Cj1capp - what are your room dimensions. Are there any windows behind speakers etc. With those informations I may be able to help or not. I also owned aerius i for 6 years.
Setting Martin Logans is a little tricky.