Acarian Alón Li'l Rascal Mk.II loudspeaker Nola Measurements

Sidebar: Measurements

I was disconcerted by the fact that both samples of the Nóla Mini rattled. It turned out that the hardwired crossover at the base of each cabinet was not securely fastened. However, this didn't affect the performance of the speakers, which appeared to be working correctly.

I estimated the Nóla Mini's voltage sensitivity at a higher-than-average 89.3dB(B)/2.83V/m, which is within the margin of error of the original Alón Li'l Rascal's sensitivity. This is to be expected, given the fact that the same woofer is used in an enclosure of very similar size. The Mini's plot of impedance magnitude and electrical phase (fig.1) is broadly similar to that of the Rascal. The impedance minima, the tuning frequency of the port, and the small wrinkle between 200Hz and 300Hz in the impedance traces (this correlated with a strong cabinet resonance at 230Hz) are all the same, but the magnitude peak in the upper midrange is not as high.

Nomfig1.jpg

Fig.1 Nóla Mini, electrical impedance (solid) and phase (dashed). (2 ohms/vertical div.)

One aspect of the original Alón speaker's measured performance that bothered me was a lack of energy between 1 and 2kHz in the tweeter-axis response. Fig.2, taken with the 1"-wide felt ring that should have been in place on the original review sample (see Bob Reina's addendum to his original review), shows the Li'l Rascal's frequency response on the tweeter axis, and the suckout can be clearly seen. Fig.3 shows the response of the Nóla Mini, again taken on the tweeter axis,1 along with the nearfield responses of the port (blue trace) and woofer (red), for comparison with those of the Li'l Rascal. Not only is the same slightly elevated upper treble apparent, but so is the upper-midrange suckout, this present to a greater degree. (This graph shows the response of sample 1171; sample 1172 was about 1dB more sensitive in the midrange but 1dB less sensitive in the low treble, with a similar suckout present between 1kHz and 2kHz.)

Nomfig2.jpg

Fig.2 Alón Li'l Rascal, anechoic response on tweeter axis at 50", averaged across 30° horizontal window and corrected for microphone response, with the nearfield response of the woofer (red) and port (blue) plotted below 300Hz and 1kHz, respectively, along with complex sum (black).

Nomfig3.jpg

Fig.3 Nóla Mini, anechoic response on tweeter axis at 40", averaged across 30° horizontal window and corrected for microphone response, with the nearfield response of the woofer (red) and port (blue) plotted below 300Hz and 1kHz, respectively, along with complex sum (black).

I always measure speakers on the tweeter axis because it is a measurement that is readily repeatable. However, it is fair to point out that Alón recommended that the Li'l Rascal be listened to on an axis a couple of inches below the tweeter, and I assume that the same advice applies to the Nóla Mini. However, my plot of the Rascal's vertical dispersion (fig.6 in the Web reprint) showed that the suckout didn't fill in to any significant degree until the listener was well below the woofer axis. The speaker did have excellent horizontal dispersion, however.

The Nóla Mini's step response (not shown) was effectively identical to that of the Li'l Rascal, as was its cumulative spectral-decay plot (fig.4).

Nomfig5.jpg

Fig.4 Nóla Mini, cumulative spectral-decay plot at 50" (0.15ms risetime).

Its somewhat idiosyncratic measured performance aside, the Nóla Mini appears to be very similar to the Alón Li'l Rascal. Speaking personally, I found the lack of energy in the upper midrange disappointing, but if you liked the sound of the earlier speaker, as BJR did, then you'll like the sound of this new one, as BJR also did.—John Atkinson



Footnote 1: Continued torrential rain in New York City in October meant that I had to measure the Nóla Mini indoors at a microphone distance of 40" instead of outdoors at a microphone distance of 50".—John Atkinson
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