MartinLogan Aerius loudspeaker Measurements part 2

The panel's output is less easy to interpret. The top octave is shelved down, while the mid- and low-treble are broken up by peaks and notches which may be due to resonances, or to interference effects specific to the particular microphone position chosen. The peak at 420Hz and the suckout just above that frequency might be at least partly due to the nearfield microphone technique. The panel can be seen to roll out very quickly below 300Hz, however.

Looking at how these two responses integrate at a 45" distance, fig.5 shows the quasi-anechoic response averaged across a 30-degree horizontal window to minimize the effect of mike-position-dependent interference effects. It gently and smoothly slopes down by some 4dB through the midrange and low treble. The mid-treble still looks messy, however, and the top octave is shelved down. The latter, however, will be at least partly due to proximity effect, as explained in my Quest Z measurements elsewhere in this issue. Nevertheless, the response in my listening room (fig.6) was still a little lacking above 10kHz, which correlates with my feeling that the speaker's sound lacked top-octave air. Overall, however, the in-room response of the Aeriuses is very smooth, with a very slight prominence of low-treble energy which might explain the way the speaker slightly emphasized tape hiss. (Ignore the peaks and dips in fig.6, which are room effects that have not been minimized by the spatial averaging used to derive this graph.)

Fig.5 MartinLogan Aerius, anechoic response on-axis at 45", averaged across 30 degrees horizontal window and corrected for microphone response, with the nearfield woofer response plotted below 300Hz.

Fig.6 MartinLogan Aerius, 1/3-octave, spatially averaged in-room response.

Moving on to how the speaker's balance changes as a listener moves to its side (fig.7, only differences shown), the Aerius is basically omnidirectional within the woofer's passband. The bipolar panel output, however, increasingly shelves down with off-axis angle, though not without some peakiness appearing in the high treble. The flattest high-frequency balance is to be obtained with the speakers toed-in to the listening seat. Vertically (not shown), the speaker's output is relatively uniform as long as your ears are between 33" and 40" from the floor. The treble gets very peaky between 40" and the top of the panel, however, while moving above or below the panel results in severely depressed highs—don't listen to the Aerius standing up!

Fig.7 MartinLogan Aerius, lateral response family at 45", normalized to response on tweeter axis, from back to front: differences in response 90 degrees-15 degrees off-axis, reference response, differences in response 15 degrees-90 degrees off-axis.

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