Hansen Audio Prince V2 loudspeaker Measurements

Sidebar 3: Measurements

With a speaker as large and heavy as the Prince V2, there is no question of lifting it onto a tall stand for the acoustic measurements, to move back in time the inevitable reflection from the floor between the speaker and the microphone. As a result, my measurements don't have as much detail in the lower midrange as usual, but I don't believe that fact invalidates my findings. (My thanks to Wes Bender, Stephen Mejias, and Danny Gonzalez for their help in moving these speakers around for the measurements.)

My estimate of the Prince's voltage sensitivity on its tweeter axis was a little lower than specified, at 85dB(B)/2.83V/m. This speaker will definitely benefit from being driven by a powerful amplifier, particularly as its impedance (fig.1) drops below 4 ohms in the mid-treble and above. The impedance rises with decreasing frequency below 1kHz, which means that tube amplifiers, with their relatively high source impedance, will sound heavier in the bass than solid-state amplifiers with the Hansen. But as the Prince V2's impedance at lower frequencies doesn't drop below 8 ohms, this speaker should work well with tube amps. The traces in fig.1 are free of the glitches and wrinkles that would indicate the presence of cabinet resonances of various kinds. Investigating the panels' vibrational behavior uncovered nothing untoward. This is an acoustically inert enclosure.

Fig.1 Hansen Audio Prince V2, electrical impedance (solid) and phase (dashed). (2 ohms/vertical div.)

The sharply defined saddle at 31Hz in the impedance-magnitude trace reveals that this is the tuning frequency of the large, rectangular reflex port. This is confirmed by two things: 31Hz is also the woofer's minimum-motion frequency (fig.2, blue trace), and the port's output peaks in this region (fig.2, red). The port can be seen to have some peaks in its stopband output, but these are well down in level. The woofer also rolls off very slowly, due to the use of a first-order crossover to the midrange driver (fig.2, green). The crossover frequency between these two drive-units lies at 100Hz, exactly as specified, which leads to some concern on my part. Not only does this mean that there is broad overlap in the bass among the woofer, port, and midrange outputs—the black trace below 300Hz in fig.2 is the complex sum of the three radiators' outputs, taking acoustic phase into account—but the midrange driver's response then smoothly rises until it reaches the crossover frequency to the tweeter at approximately 2.2kHz. The apparent bump in the Prince's overall midbass output is due in part to the nearfield measurement technique, but this will, to some extent, balance the rise in response in the upper midrange. This will be especially true if the speaker is used with a tube amplifier, for the reasons explained earlier.

Fig.2 Hansen Audio Prince V2, anechoic response on tweeter axis at 50", averaged across 30° horizontal window and corrected for microphone response, with the complex sum of the nearfield responses plotted below 300Hz (black), and with the the nearfield responses of the port (red), woofer (blue), and midrange (green) plotted in the ratio of the square root of their radiating areas.

What this behavior implies about the Prince V2's sonic character will depend on what frequency region the ear takes as its reference—and that, in turn, will depend on what music is being played. On the positive side, the energy excess at the top of the midrange will accentuate recorded detail and enhance the reproduction of female voices—Wes Phillips did note how wonderfully the Hansens handled voices of all sorts—but the balance might also lead to some fatigue with overcooked recordings, as well as project some sources more forward in the soundstage. Alternatively, if the ear locks on to the upper midrange as its sonic anchor, the relative lack of lower-midrange energy will make male voices sound a bit thin, and orchestras somewhat anemic. Note that WP did remark that the Princes presented the large ensemble in Schulhoff's Double Concerto for Flute and Piano a shade less forcefully than did the Wilson WATT/Puppy 8s, and that the overall ensemble sound was a touch smaller—which is what I would expect.

The tweeter's response is basically flat, but with some small peaks on-axis balanced by equally small dips. And as you can see from the Prince's lateral-dispersion plot (fig.3), the largest on-axis suckout, between 4 and 6kHz, does tend to fill in to the speaker's sides, meaning that its in-room balance in this region will be neutral. The tweeter can be seen to get quite directional above 10kHz, but the contour lines below 4kHz in this graph are evenly spaced, which correlates with the excellent stereo imaging noted by WP. In the vertical plane (fig.4), a suckout at the upper crossover frequency of 2.2kHz develops more than 5° above the tweeter axis, but the speaker does maintain its balance quite well for axes below the tweeter.

Fig.3 Hansen Audio Prince V2, 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.4 Hansen Audio Prince V2, vertical response family at 50", normalized to response on tweeter axis, from back to front: differences in response 15–5° above axis, reference response, differences in response 5–10° below axis.

To examine how these quasi-anechoic measurements added up in Wes's listening room, I derived my usual spatially averaged in-room response from 10 individual 1/6-octave–smoothed spectra taken individually for the left and right speakers in a vertically oriented grid 40" wide by 18" tall and centered on the position of WP's ears in his listening chair. (For this measurement, the speakers were driven by a Musical Fidelity Nu-Vista 300 power amplifier.) The result is shown in fig.5. There is a slight energy excess between 500Hz and 1.2kHz, but above that region, the Princes' response in-room is basically flat until, due to the increasing absorption of the room's furnishings in the top two audio octaves, it smoothly slopes down with increasing frequency. The port doesn't fully extend the speaker's low-frequency output, which surprised me. The woofer's output integrates quite well with Wes's room, though the depression at 125Hz and the peak at 70Hz are mainly due to the influence of room acoustic problems that have not been eliminated by the spatial averaging. However, the lack of lower-midrange energy seen in fig.2 is still evident in this graph.

Fig.5 Hansen Audio Prince V2, 1/6-octave, spatially averaged response in WP's listening room.

Turning to the time domain, the Prince V2's step response is shown in fig.6. A short, positive-going step from the tweeter is followed first by a negative-going step from the midrange unit, then a positive-going step from the woofer. Despite its use of first-order crossover filters and a stepped-back front baffle, the speaker is not time-coincident. It is, however, time-coherent: connecting the midrange unit in inverted polarity allows each drive-unit's step to smoothly hand over to that of the next lower in frequency. The Prince's cumulative spectral-decay plot (fig.7) is not as clean as I expected, with some low-level residual hash evident in the mid-treble.

Fig.6 Hansen Audio Prince V2, step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth).

Fig.7 Hansen Audio Prince V2, cumulative spectral-decay plot at 50" (0.15ms risetime).

In many respects, the Hansen Audio Prince V2 acquitted itself well on the test bench. But I was puzzled by the decision to cross over from the woofer to the midrange unit at a frequency as low as 100Hz.—John Atkinson

Hansen Audio, Inc.
100 Leek Crescent, Unit 9
Richmond Hill, Ontario L4B 3E6
(905) 731-8434