Floor Loudspeaker Reviews

I used DRA Labs' MLSSA system, a calibrated DPA 4006 microphone, and an Earthworks microphone preamplifier to measure the JansZen Valentina P8's frequency response in the farfield. I used an Earthworks QTC-40 mike for the nearfield and in-room responses. My primary axis for the measurements was at 90° from the center of the electrostatic panel on the angled front baffle at a distance of 50". (I refer to this as the "normal" axis.) I raised the loudspeaker as far as possible from the floor, but the reflection of the lower woofer's output from the floor meant that I had to window the measured impulse responses more aggressively than usual, which reduces the midrange resolution of the FFT-derived frequency responses. Although the P8 is specified as handling steady-state powers up to 120W, the manual warns that performing tests that involve swept sinewaves or impulse signals can damage the electrostatic panel. I therefore kept the SPL at or below 86dB for the measurements.

JansZen specifies the Valentina P8's anechoic sensitivity as 87dB/W/m. I found that the measured sensitivity varied somewhat with the exact measurement axis. My B-weighted estimate was between 83dB/2.83V/m and 84dB/2.83V/m. This correlates with my impression that the JansZen speaker was less sensitive than the GoldenEar BRX, which had an estimated sensitivity of 87.5dB(B)/2.83V/m.

The Valentina P8's impedance is specified as 6 ohms, with a minimum value of 4 ohms. The measured impedance varies with the setting of the drive-unit level controls. The solid traces in fig.1 show the impedance magnitude, measured with Dayton Audio's DATS V2 system, with the controls set to their maximum and minimum values. The level of the peak at 58Hz, which indicates the tuning frequency of the woofers, varies from 8.8 ohms with the woofers set to +3dB to 33 ohms with them set to –3dB.

Fig.2 shows the JansZen loudspeaker's impedance magnitude and electrical phase angle with the controls at my preferred settings: woofers at 0dB, electrostatic panel at +1dB, and side-mounted tweeter at –4dB. The impedance magnitude (solid trace) averages the specified 6 ohms, with a minimum value of 4 ohms at 20kHz. The phase angle (dashed trace) is generally low, which means that the effective resistance, or EPDR (footnote 1), lies above 4 ohms for much of the audioband. It does drop below 4 ohms between 71Hz and 120Hz, 295Hz and 541Hz, and above 3.35kHz, with minimum values of 3.6 ohms at 407Hz and 1.83 ohms at 20kHz. Overall, however, the Valentina P8 is a relatively easy load for the partnering amplifier.

The traces in figs.1 and 2 are free from the small discontinuities that would imply resonances. When I investigated the enclosure's vibrational behavior with a plastic-tape accelerometer, all the panels were relatively inert. The only resonant modes I found were on the back panel. The highest-level mode was at 689Hz just below the level control for the dome tweeter (fig.3), but this is still very low in level.

The green trace below 350Hz in fig.4 shows the sum of the nearfield outputs of the two woofers, which behave identically. The slight peak in the midbass region is due in part to the nearfield measurement technique, which assumes that the drive units are mounted in a true infinite baffle, ie, one that extends to infinity in both planes. The woofers' output rolls off at the sealed-box rate of 12dB/octave below the tuning frequency. The woofer level control was set to +3dB for this graph; set to 0dB the switch reduces the level by 3.1dB and by another 3dB at the –3dB position.

The output of the woofers crosses over to the electrostatic panel's output (fig.4, red trace) at 850Hz, which is higher than the specified 500Hz. However, reducing the level of the woofers will lower the crossover frequency, as well as bringing the average level of the woofers closer to that of the electrostatic panel. The panel's response on the measurement axis described earlier has a lack of energy in the mid-treble region. The panel's level was set to +1dB for this graph. Setting the control to 0dB reduced the level by 1dB; setting it to the minimum gave a further 1.8dB reduction in level.

The blue trace in fig.4 shows the response of the side-mounted tweeter set to its maximum level, which peaks in the top audio octave. Adjusting its level control to my preferred setting reduced the tweeter's output by 3.6dB.

The black trace in fig.5 shows the Valentina P8's quasi-anechoic farfield response, averaged across a 30° horizontal window centered on the normal axis. The lack of mid-treble energy is exacerbated by the spatial averaging, as the electrostatic panel, with its large width, is extremely directional at higher frequencies. This can be seen in fig.6, which shows the Valentina P8's horizontal dispersion, normalized to the response on the normal axis, which thus appears as a straight line. I also found that the panel's flattest treble response was obtained 3" below this axis, which I have shown as the red trace in fig.5. However, the output on this axis falls off rapidly above 9kHz. Presumably, these differences will be due to the different vertical angles of the two halves of the electrostatic panel. As I found in my auditioning, small changes in listener height and toe-in produce relatively large changes in the loudspeaker's tonal balance.

Fig.7 shows the JansZen Valentina P8s' spatially averaged response (footnote 2) in my room with all three level controls set to their maximum (red trace) and minimum (blue trace) levels. As shown in fig.4, the output of the woofers set to +3dB is too high in level compared with the output of the ESL panel. The bump between 600Hz and 700Hz also appears to be associated with the woofers. The Valentina's in-room treble output rolls off gently and relatively smoothly in the top three audio octaves.

The red trace in fig.8 shows the spatially averaged response of the JansZens with their controls set to my preferred positions, but without the final toe-in. The average response is flat from 100Hz to 4kHz, though with slight peaks between 600Hz and 700Hz and at 2kHz. For reference, the blue trace in fig.7 shows the spatially averaged response of the Bowers & Wilkins 804 D4s, which I reviewed in January 2022. These reflex-loaded speakers excite the lowest frequency mode just above 30Hz in my room to a greater extent than the Valentina P8s. The JansZen speakers are better-behaved than the B&Ws in the high treble, however, with the desirable gentle downward slope with increasing frequency due both to the increased absorption of the room's furnishings and to the P8's narrow high-frequency dispersion.

In the time domain, the Valentina P8's step response (fig.9) indicates that the drive units are connected in positive acoustic polarity, with the decay of the panel's step, which arrives first at the microphone, smoothly blending with the start of the woofers' step. The Valentina P8's cumulative spectral-decay plot on the axis 3" below the normal axis (fig.10) is very clean in the region covered by the electrostatic driver. However, there are ridges of delayed energy at the top of the woofers' passband.

The JansZen Valentina P8's measured performance indicates that, when optimally set up, it will give an even tonal balance. However, the measurements also suggest that, as I found, optimizing the speakers' setup is a complex business.—John Atkinson

Footnote 2: Using the FuzzMeasure 3.0 program, a Metric Halo MIO2882 FireWire-connected audio interface, and a 96kHz sample rate, I average 20 1/6-octave–smoothed spectra, individually taken for the left and right speakers, in a rectangular grid 36" wide by 18" high and centered on the positions of my ears.