Can you correct nulls with acoustic treatments.

OK, this is not supposed to work with Magnepans but you have to follow the trail and see where it leads, if that makes sense.

I try what is written in the Genelec sites, that Shadorne has lead me to, about positioning to avoid 1/4 wave cancelations. According to everything written (their manual and everywhere else I have read) about positioning Maggies, they should be as far out from the back wall as possible.

Well shoot.... I do the calculations on the site, follow their recommendation to keep back wall distance 1 meter or less, and figure I am trading one set of cancelations for another. Low and behold, I move the speakers back from 50 some odd inches to about 30" from the back wall and play Patti Smith's Gung Ho, (not exactly an Audiophile recording but what the hey). OMG, the bass is up a notch and very clear! I mean, it is not subtle.

Ok, so I measure with my limited means and where I thought I would have traded an 60 or 90hz. null for a 110hz. null. the 60 was still there, the 90 wasn't as deep and the broad 100hz. to 160 hz. deep null was just gone. Replaced by a slight bump.

Ok, what is going on? I do the calculations for a 1/2 wave and it should be close to the 1/4 wave but instead there is a null at 230-240hz. Back to reading!

Anyway, what shouldn't work with Maggies does. At least in my room.

In all fairness it does generate some other issues. The tweeters are now close enough to the back wall and directionally pointed at the listening position to beam. Also brings into play reflections from a patio door behind and to the left of the LP that wasn't a concern before. Lessened those effects by tilting the speakers back a little.

FWIW,
Jim S.

Jim,

The Maggies should still respond to the same physics in the bass as Genelec describes, however, they radiate front and back in ALL frequencies (not just the LF below 500 Hz) and, therefore it will be recommended to have them as far out as possible - say in the middle of the room. (Soffit mount is not an option and will kill that beautiful atmospheric/ambient sound from the higher frequencies going in all directions). I have not owned these kind of speakers, however, the best demo I have heard was with these type speakers towards the middle of the room.

Shadorne, you're a good man. You have helped through the foolishness and learning.

I think it goes something like this.... Place the 1.6's for the best soundstage coherence? Trap for standing waves and trap for quarter wave cancelations? Readjust, remeasure, readjust?

Absorb and diffuse for the rest? I still don't understand the rest, but I have some reading material coming that I hope will help.

Everyone that shared their advice was correct in their way. Measurement, placement, appropriate treatments are part of the equation. You can quit anywhere along the process you are happy with the results.

And....... yes, I am headed for a little bit of "Flash Gordon", but what the heck, life is getting really short!
And, yes, 8' out into the room puts the quarter wave cancelation at 35hz. Yes, it does sound really, really good, if not practical.

Cheers, and Good Evening,
Jim S.