Where 2 sit audio quiz

This is strictly a guess, so take it for what it is worth.

My "guess" is that the reflection from the back wave of your Maggies is "colliding" with the front wave at these distances. As such, you're experiencing out of phase cancellation, reducing the spl. The reason that this takes place over a specific area is that sound waves are all different lengths. One batch of frequencies is nulled at 16', another batch at 18' and the frequencies between those points at 17'. As such, you have a noticeable broad band dip at this specific distance.

In front and behind those distances, you'll experience reinforcement of those frequencies ( to varying degrees ) but cancellation of other frequencies. The key is to find the point that allows the most neutral tonal balance while still allowing good to optimum soundstaging / imaging. Since a microphone and test gear don't hear or process information the same as our brain does, using equipment and tools to get you in the area is fine, but trust your ears.

As far as doing the math to figure out the wavelengths and reflected paths, a room with irregular shapes, sizes and / or irregular non-solid objects that break up reflections can cause pretty erratic results. This is the reason that the acoustic modeling program called C.A.R.A. wants to know as much as possible about your room, it's shape and size, what you have in it, the speakers radiation pattern, etc... The more info that one can provide an acoustician or a program similar to CARA with, the more likely the results are to be accurate.

As far as "boosting" the spl's and linearizing the frequency response at that distance, this can be done. It will take a lot of work and will completely change the presentation that you hear at any given distance. This is because you'll be "squashing" the back wave to minimize cancellations and reflections. In effect, you will probably end up losing many of the desirable attributes of the Maggies that attracted you to them to begin with.

As a side note, with Maggies at 12' apart with a very mild amount of toe-in, 16' - 18' is too far back in my opinion. Then again, i don't know the specifics of the room or anything else about this installation, so keep experimenting and learning as you go. This can be a very educational and beneficial time for you in terms of learning via first hand experience. If you really get serious and start doing a lot of experimenting, keep a notebook. I would also make cohesive notes, not just jot down things at random. You might not look at these notes for a while and by that time, you may have forgotten some of the specifics of your "abbreviated" notes. Sean
>

Sean, you make the point that speakers beam at higher frequencies and are less linear off axis. Are you then of the opinion that speakers should be toe'd in for best overall frequency response?

If there is a high frequency hole at the listening area, can it be boosted by toeing in the speakers to get a more direct on axis presentation?

I am aware that while many speaker placement methods recommend some toe in, at least one major speaker manufacturer states that best results are achieved with little or no toe in.

Also for both of you, what are the effects on sound stage width and depth as one adds toe in? Can it be predicted or is it room dependent?

Thanks,

I did a post not that long ago giving a brief run-down on the method that i generally use for setting up speakers. It is somewhat of a universal approach that works regardless of room or speaker size and takes into account tonal balance and soundstage / imaging. Only problem is, i can't remember what thread it was in and it's too long to type out again. I'll see if i can find it or hopefully, someone else will point us to it. Sean
>

PS... As a general rule, i prefer little to no toe in. Then again, that is with using the approach that i mentioned above.

Aargon: Found the thread that i posted a basic and relatively universal speaker set up method in. It it just so happens that Rooze started that one too : )

Look for a thread of his entitled "problems with Maggie 3.6's" or something to that effect. This should answer your questions and then some. Sean
>

Thanks, your method is straightforward. I put my 5As on baking pans and started pushing them around per the process earlier this evening. It was easy to hear the modal variations, and detect when the female voice image was solid. I will back this up with measurements from my RTA in the AM.