Sonus Faber Guarneri Evolution loudspeaker Measurements

Sidebar 3: Measurements

The Sonus Faber Guarneri Evolution's B-weighted sensitivity on its tweeter axis was 85dB/2.83V/m, which is slightly lower than the specified 86dB and significantly lower than the norm. The electrical impedance (fig.1) remains above 5 ohms from the bass through the low treble, but drops to a minimum value of 4 ohms between 4 and 5kHz. The electrical phase angle is generally benign, but there is a combination of 5 ohms and –45° at 3200Hz that will require the use of a good, 4 ohm-rated amplifier with this speaker. A small wrinkle between 200 and 300Hz in the impedance traces correlates with a cabinet resonance at 254Hz that was detectable on the enclosure's side panels (fig.2). As Art Dudley didn't remark on any coloration that could be laid at the door of this behavior, I suspect this measurement looks worse than it sounds. (It is of very high Q or Quality Factor, which will work against its audibility; in addition, I couldn't detect this resonance on the enclosure's other surfaces.)

Fig.1 Sonus Faber Guarneri Evolution, electrical impedance (solid) and phase (dashed). (2 ohms/vertical div.)

Fig.2 Sonus Faber Guarneri Evolution, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of side panel (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz).

Fig.3 shows the individual outputs of the port (red trace), woofer (green), and tweeter (blue). The woofer's minimum-motion point occurs at 43Hz, as predicted by the impedance curve, which has a saddle in the magnitude trace at that frequency, and the port's output peaks between 30 and 100Hz. The port's output rolls off smoothly above 100Hz, and is free of the pipe resonances that so often afflict small reflex-loaded speakers. Both the woofer and tweeter, measured on the tweeter axis, are flat within their passbands, with the crossover set at 2.9kHz, very close to the specified 2800Hz. Both drive-units are well behaved outside their operating regions.

Fig.3 Sonus Faber Guarneri Evolution, acoustic crossover on tweeter axis at 50", corrected for microphone response, with nearfield woofer (green trace) and port (red) responses plotted below 300Hz and 1kHz, respectively.

Fig.4 shows how these outputs sum in the farfield, averaged across a 30° horizontal window centered on the tweeter axis. The bump in the upper bass is entirely due to the nearfield measurement technique used to capture the drivers' low-frequency behavior; the speaker will be flat down to around 70Hz, with the output down 6dB at the port tuning frequency of 43Hz, which is close to the lowest note of the four-string electric and orchestral basses. The Guarneri Evolution is also extremely flat in response throughout the midrange and treble.

Fig.4 Sonus Faber Guarneri Evolution, anechoic response on tweeter axis at 50", averaged across 30° horizontal window and corrected for microphone response, with complex sum of nearfield woofer and port responses plotted below 300Hz.

Despite its flat and extended top-octave output on axis, AD found the Sonus Faber to sound a little mellow. This is explained by the plot of the speaker's lateral dispersion normalized to its on-axis response (fig.5). The tweeter becomes quite directional above 9kHz or so, which will reduce the top-octave energy level in all but very small, live rooms. Other than that, the Guarneri Evolution's horizontal dispersion pattern is textbook in its evenness, with no off-axis peaks or suckouts to color the reverberant soundfield. In the vertical plane (fig.6), a suckout develops above the tweeter axis, but the balance doesn't change significantly for 10° below that axis. Sonus Faber's 31"-tall stands are optimal for this speaker.

Fig.5 Sonus Faber Guarneri Evolution, 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 Sonus Faber Guarneri Evolution, 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.

In the time domain, the Guarneri Evolution's step response on the tweeter axis (fig.7) indicates that the drive-units are connected in the same positive acoustic polarity. The smooth blend of the decay of the tweeter's step into the rise of the woofer's step correlates with the excellent integration of their outputs in the frequency domain on this axis. This is a testament to the crossover design. Finally, the cumulative spectral-decay plot (fig.8) demonstrates a superbly clean decay, with no ridges of decayed energy to suggest the presence of resonances. (The black ridge just below 16kHz is the usual leakage from my computer's video circuitry.)

Fig.7 Sonus Faber Guarneri Evolution, step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth).

Fig.8 Sonus Faber Guarneri Evolution, cumulative spectral-decay plot on tweeter axis at 50" (0.15ms risetime).

Yes, this gorgeous little speaker is expensive. But its superb measured behavior both correlates with its superb sound quality and suggests that Sonus Faber has some serious speaker-engineering expertise on its staff. It also measures better in many respects than the speaker it replaces, the Guarneri Memento, which Michael Fremer reviewed in August 2007.—John Atkinson

Company Info
Sonus Faber SPA
US distributor: Sumiko
2431 Fifth Street
Berkeley, CA 94710
(510) 843-4500
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Comments
Dan Moroboshi's picture
Follow up should be very interesting

I do respect from all of Art's considerations and my interpretation from all of that is that a gear in the system should match to the other components of the system. I interpretated that those Sonus Faber did not match with the tube amp (and magnificent) from Art.

I sugest a follow up with more juice (power) and solid state amplifiers. I think that Art also comment of this possibility on the review, right?

Doctor Fine's picture
Sonus Faber

Great review, Art.  I too find the Guarneri series in its earlier incarnations to be especially intolerant of anything less than a fully "locked in" room placement.  The Sumiko Masters Method of finding room modes that load this speaker is an absolutely essential component of its performance.

The thing about Sonus Faber your readers might not have comprehended is that there is much pleasure in simply owning them so that you can look at them.  Like having a fine concert violin out in your room as a decorative prop and reminder of things handmade (the name "Sonus Faber" refers to hand-made sound, there's your hyphen again).

Not to take anything away from the Wilson Sophia, in comparison,  which is also an incredible speaker and handsome in its way, but looking at the Sonus sure beats looking at damn near anybody else's box...

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