Originally Posted by Speqtre
Wow, Jon, thanks for the comprehensive, and quick, answer!
Understood about the doubled midbass output on the A2 - makes sense, especially after reading LTD02's thread...
By cohesive directivity, do you mean it has a narrower 'sweetspot'? Is the MTM design of the A2 subject to the condition known as 'lobing' mentioned in other threads? How do the depth and width of the soundstage compare on the A1 and A2?
Also, what would you consider a 'somewhat enclosed space'? A 10'x10' room, a 14'x20' room, or...?
You're certainly welcome. Last question first: The MTM style (as opposed to the true d'Appolito symmetrical array, at least as I recall it) has symmetrical lobing along the long axis, with one null on either side of the perpendicular (tweeter) axis that depend on crossover type and driver alignment for severity. The true, aligned, 1st order MTM (or d'Appolito array, IIRC) has no such lobing, but rather a rather mild rippling of amplitude as one measures across the array's long axis. It also has perfect impulse response.
The majority of mid-treble-mid arrays are not true d'Appolito arrays, as such are difficult to construct without fairly specialized drivers and because power handling can be limited. The same will hold true for the Acculine A2 (although its tweeter has excellent bandwidth and power handling, should we want to explore that feature in an alternate design one day.)
The benefit the A2 and other similar MTM's have is the increased power handling afforded by their crossover's steeper stopbands. The A2 therefore takes more power and goes louder, plus it has a relatively constant on-axis response -- it's flat on axis and it's off axis response sums relatively flat as well, although it has the usual lobes virtually all MTM's have.
The A1, on the other hand, like all vertical asymmetrical "arrays" always has a distinct lobe pattern. The A1 should therefore be used vertically at approximately ear level, as this places the listener somewhere roughly in the speaker's intended, flattest response soundfield. Standing well above or lying on the floor below any conventional array of two different drivers crossed over to differing bandwidths typically puts a listener in a non-flat portion of the speaker's vertical directivity pattern -- the usual "lobing" occurs -- and that's due to a host of factors.
A "more cohesive directivity" is a subjective coined phrase, one I intend to point out that the A2 has a more predictable, usable off-axis response to left and right when used horizontally than the A1 (or any other conventional 2-way) would when used horizontally, a placement we wouldn't recommend. The A2 also has the benefits of that fabulous planar tweeter, including it's ability to be rotated for maximum horizontal dispersion regardless of the speaker's installed axis.