Avantgarde Acoustic Uno Series Two loudspeaker:
Measurements part 2
Higher in frequency, though there are a series of small peaks and dips evident, the overall balanced trend is very flat—certainly the flattest I have personally measured with a horn speaker. The very top octave is slightly hotter than the region below, which I could hear in the nearfield as just a slight emphasis to the hissy MLSSA noise when I was measuring the speaker. However, I note that RD was not bothered by this excess high-treble energy, which means that in-room, it might well be compensating for the speaker's off-axis behavior.

I have shown the Avantgarde's lateral off-axis behavior in two ways: fig.4 shows the actual responses to the speaker's sides; fig.5 shows just the differences between the off-axis responses and the central, design-axis response. First, note the flare to the speaker's sides in the lower midrange. The cancellation notch between the midrange and the woofer occurs exactly on-axis and becomes less deep off-axis.

Fig.4 Avantgarde Uno, lateral response family at 50", from back to front: responses 90 degrees-5 degrees off-axis, reference response on design axis, responses 5 degrees-90 degrees off-axis.

Fig.5 Avantgarde Uno, lateral response family at 50", normalized to response on design axis, from back to front: differences in response 90 degrees-5 degrees off-axis, reference response, differences in response 5 degrees-90 degrees off-axis.

Second, note that, with the exception of the upper crossover region, the "contour lines" are very even. The physical design of the two horns and the frequency ranges they cover have been carefully chosen to given a consistent radiation pattern. It can be seen that the midrange horn does have a slightly wider dispersion than the tweeter horn, however, the latter's output falling uniformly by 24dB approximately 45 degrees to the speaker's sides. All things being equal, this would tend to make the speaker sound rather dull in large, overdamped rooms. But given the on-axis rise in response, the speaker's highs in more typical rooms will actually tend to sound better balanced as a result.

In the vertical plane (fig.6), the high frequencies are well-maintained in the ±10 degrees shown. However, various peaks and dips occur off-axis in the low-treble, suggesting that the listener sit with his or her ears on the intended axis.

Fig.6 Avantgarde Uno, vertical response family at 50", normalized to response on design axis, from back to front: differences in response 10 degrees-5 degrees above axis, reference response, differences in response 5 degrees-10 degrees below axis.