ASW Genius 100 loudspeaker Measurements

Sidebar 3: Measurements

My estimate of the ASW Genius 100's voltage sensitivity on its tweeter axis was 88dB(B)/2.83V/m, which is slightly above average but 2dB lower than the specification. The speaker's impedance did drop to 4 ohms around 200Hz, and there is a combination of 5.8 ohms and –40° electrical phase angle at 130Hz, but overall, the ASW is not as hard to drive as its 4 ohm specification would suggest.

The traces in fig.1 are free of the wrinkles that would imply the existence of cabinet resonances. While investigation of the panels' vibrational behavior with an accelerometer did uncover a strong mode around 750Hz (fig.2), I feel that this is too high in frequency to have any subjective consequences.

Fig.1 ASW Genius 100, electrical impedance (solid) and phase (dashed). (2 ohms/vertical div.)

Fig.2 ASW Genius 100, cumulative spectral-decay plot calculated from the output of an accelerometer fastened to the center of the sidewall (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz).

The low-frequency saddle centered at 51Hz in the impedance-magnitude trace suggests that this is the tuning frequency of the reflex port on the rear panel, which is confirmed by the minimum-motion notch in the woofer's nearfield response (fig.3, blue trace) at the same frequency. The port's output (fig.3, green) is a classic bandpass centered on the tuning frequency, and its upper-frequency rolloff is commendably free of resonant modes. The woofer can be seen to cross over to the tweeter (fig.3, red) in a well-behaved manner at around 3.5kHz, with the latter balanced a couple of dB too high in level.

Fig.3 ASW Genius 100, acoustic crossover on tweeter axis at 50", with the tweeter shown in red and the nearfield responses of the woofer (blue) and port (green), plotted in the ratios of the square roots of their radiating areas below 350Hz and 750Hz, respectively.

The Genius 100's farfield response with its grille off (which is how it measured best), averaged across a 30° horizontal angle on the tweeter axis, is shown to the right of fig.4. It is fairly flat from the midrange through the mid-treble, but the top octave is elevated. I suspect that this is why BJR found that sibilants sounded "clean, crisp, and extended" rather than the speaker sounding bright per se, which tends to correlate with problems in the mid-treble. The complex sum of the woofer and port nearfield responses, taking into account acoustic phase and the different distance of each radiator from a nominal farfield point, is shown below 300Hz in fig.4. The usual hump in the upper bass that results from the nearfield measurement technique is suppressed, implying that the reflex alignment is overdamped, which would favor definition over bass weight. I note that BJR was impressed by the Genius 100's low-frequency clarity. The speaker's bass rolls off with the expected 24dB/octave slope below the port tuning frequency.

Fig.4 ASW Genius 100, anechoic response averaged across 30° horizontal window on tweeter axis at 50" and corrected for microphone response, with the complex sum of the nearfield responses plotted below 300Hz.

The ASW's plot of lateral dispersion (fig.5) indicates that the woofer's 4" cone gets a little more directional above 1kHz than I would have anticipated, with then a slight off-axis flare apparent in the bottom octave of the tweeter's passband. I wouldn't have expected this to lead to the brightness BJR noted when he played the speaker at high volumes. The tweeter is considerably more directional above 10kHz than is usual for a 1" dome. In rooms of normal size, this will tend to counteract the on-axis boost in the same region. The plot of the Genius 100's vertical dispersion (fig.6) suggests that the speakers be used with stands that place the listener's ears level with or below the tweeter. A major suckout develops in the crossover region immediately above that axis.

Fig.5 ASW Genius 100, lateral response family at 50", normalized to response on tweeter axis, from back to front: differences in response 90–5° off axis, reference response, differences in response 5–90° off axis.

Fig.6 ASW Genius 100, vertical response family at 50", normalized to response on tweeter axis, from back to front: differences in response 45–5° above axis, reference response, differences in response 5–45° below axis.

The ASW's step response on the tweeter axis (fig.7) reveals that the two drive-units are connected with the same positive acoustic polarity, and that the decay of the tweeter's step is neatly integrated with that of the woofer. Some slight low-frequency ringing can be seen in the decay of the woofer step, which is also evident in the speaker's cumulative spectral-decay plot (fig.8) as the small amount of delayed energy just above 1kHz. This graph is otherwise superbly free of resonant modes, so I'm not sure what led BJR to find that the speaker sounded bright at high levels. Most probably, given his comments about playback level, it was distortion from the small woofers being asked to move more air than they are capable of, the Genius 100's overall clarity leading the listener to inadvertently play music at louder levels than a less-clear small speaker might tempt him to do.

Fig.7 ASW Genius 100, step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth).

Fig.8 ASW Genius 100, cumulative spectral-decay plot on tweeter axis at 50" (0.15ms risetime).

Overall, its measurements reveal that this little German speaker demonstrates some excellent engineering.—John Atkinson

ASW Lautsprecher GmbH
US distributor: May Audio Marketing
2150 Liberty Drive, Unit 7
Niagara Falls, NY 14304-4517