JansZen Valentina P8 loudspeaker Measurements

Sidebar 3: Measurements

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.1 JansZen Valentina P8 with controls set to their maximum and minimum settings, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).

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.


Fig.2 JansZen Valentina P8 with controls set to JA's preferred settings, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).

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.


Fig.3 JansZen Valentina P8, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of back panel below the tweeter level control (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz).

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.


Fig.4 JansZen Valentina P8, acoustic crossover on normal axis at 50", corrected for microphone response, with the response of the auxiliary side-mounted tweeter (blue) and the response of the woofers set to +3dB (green, nearfield below 350Hz).

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.5 JansZen Valentina P8 with controls set to JA's preferred settings, anechoic response on normal axis at 50", averaged across 30° horizontal window and the response 3" below that axis (red), both corrected for microphone response, with the nearfield woofer response plotted below 300Hz.


Fig.6 JansZen Valentina P8, lateral response family at 50", normalized to response on normal axis, from back to front: differences in response 90–5° off axis, reference response, differences in response 5–90° off axis.

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.


Fig.7 JansZen Valentina P8, spatially averaged, 1/6-octave response in JA's listening room with all controls set to the maximum (red) and minimum (blue).

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.


Fig.8 JansZen Valentina P8, spatially averaged, 1/6-octave response in JA's listening room with controls set to JA's preferred settings (red), and of the Bowers & Wilkins 804 D4 (blue).

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.


Fig.9 JansZen Valentina P8, step response on normal axis at 50" (5ms time window, 30kHz bandwidth).


Fig.10 JansZen Valentina P8, cumulative spectral-decay plot on normal axis at 50" (0.15ms risetime).

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 1: EPDR is the resistive load that gives rise to the same peak dissipation in an amplifier's output devices as the loudspeaker. See "Audio Power Amplifiers for Loudspeaker Loads," JAES, Vol.42 No.9, September 1994, and stereophile.com/reference/707heavy/index.html.

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.

JansZen Audio
480 Trade Rd.
Columbus, OH 43204
(614) 448-1811

RH's picture

I've been waiting for Stereophile to review the Janszen speakers! They have always intrigued me, not only from the excellent reviews and user reports, but due to their approach to using electrostatic panels in a sealed box design.

To that end, the only thing that disappointed me in the review is that I didn't see addressed what to me were the intriguing questions about such a design:

What does the Janszen design sound like relative to other electrostatics or box speakers?

Does it still have an electrostatic speaker character? Or more of a box speaker character? Or something in between?

Electrostatic speakers have a reputation for sounding particularly "quick" and vivid especially with transients, along with that famous open-window "boxless" sound.

For me (and I know many others) there is also a sort of signature to most regular electrostatic speakers where, as vivid and boxless as they sound, there is a lack of palpability, of air-moving density, that you get with a typical box speaker. It's a bit more ghostly-sounding vs flesh and blood. You hear more than feel the sound.

I've always wondered how much this has to do with the use of electrostatic panels per se, vs the fact they just have no box, and also operate as dipoles which can energize a room differently.

So I wonder if the Janszen approach of putting the panel "in a box" edges the sound more towards a box speaker (including that added density and presence), so you get a sort of melding of box speaker/electrostatic sound, or if it still sounds like an electrostatic dipole speaker, with all the usual characteristics one hears in electrostatics.

Any comment on these comparisons, Mr. Atkinson?


MattJ's picture

For me (and I know many others) there is also a sort of signature to most regular electrostatic speakers where, as vivid and boxless as they sound, there is a lack of palpability, of air-moving density, that you get with a typical box speaker. It's a bit more ghostly-sounding vs flesh and blood. You hear more than feel the sound.

Good description. I haven't heard any electrostatics other than Martin Logan's, but that summed up pretty well my reaction to them. I guess I'm not used to that type of sound, but it seemed kind of "hollow" to me.

alh22's picture

The "open" quality you describe is, in my experience, unique to electrostatics. As is the "ghosted" quality of small electrostatics (good description). The latter problem disappears when the electrostatic panels are quite large, especially compared to the size of the listening room. I have owned Quads, Beveridges, and KLH 9s (double pair), and only the 9s, when used in single pairs in a small room or doubled up in a larger room have overcome the "ghost" problem. The result can be a shocking degree of realism, at the expense of listening room real estate. Back in the '80s, the engineers at Ampex Corp. designed a giant pair of electrostats built into a wall at one end of a listening room. The realism of the sound totally overcame the poor acoustics of the bare room facing them.

MikeP's picture

KMD Orchestalls Reference speakers made in South Korea
"The World's First Speakers that Sounds Like LIVE MUSIC"
More info on You Tube !

Jack L's picture


Really? What a HUGE claim !

KMD claims their products "faithful to make ZERO energy loss" from electrical signal to audio signals.

Technically, how can any dynamic drivers like those made by KMD achieve "zero energy loss" in converting electrical energy to sound energy ??
This is physics, my friend.

KMD also claims their products were "The World's First Spealers that sounds like LIVE MUSIC. That's a huge claim !

I wonder how KMD defines its "Live Music" ?????

Listening with own ears is believing

Jack L

MikeP's picture

They were using very cheap gear, cables and CD Player too !!