Energy Veritas v2.8 loudspeaker Measurements

Sidebar 2: Measurements

JA measured the Veritas v2.8 and provided me with the results after I completed my auditioning.

The sensitivity of the Veritas v2.8 was to spec at a measured 86.5dB/W/m (B-weighted). Its impedance (fig.1) is very uniform above 30Hz. The effectiveness of the conjugate-load impedance matching is clearly visible. The upper peak of the classic "double-hump" saddle response typical of a reflex or ported enclosure has been almost completely damped—only the lower hump remains. Presumably, attempting to kill this rise would gain little and involve undesirable tradeoffs. The residual "saddle" can be seen at 28Hz—the port tuning frequency. The minimum impedance is 3.4 ohms at 600Hz. The magnitude of the impedance drops below 4 ohms in only two narrow bands; the Veritas may be safely considered a 4 ohm loudspeaker. Even the phase angle, above 30Hz, is almost purely resistive—or at least as much as would seem possible in a real-world loudspeaker. The peak at 25kHz is due to a notch filter to damp the tweeter's HF resonance.

Fig.1 Energy Veritas v2.8, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).

Fig.2 shows the FFT-calculated responses of (from left to right): the ports (nearfield), the sum of the two woofer outputs (nearfield), the midrange (nearfield up to 1kHz, at 45" on-axis from 1kHz up), and the tweeter (at 45" on-axis). The level of the port output shown here was determined by relating the area of the ports to that of the subwoofers (more precisely, by the square roots of their relative areas). The frequency at which the woofers have their minimum motion (32Hz) corresponds quite closely with the maximum output of the ports. The acoustic crossover points are at approximately 480Hz and 2.6kHz.

Fig.2 Energy Veritas v2.8, individual quasi-anechoic responses of ports, woofers, midrange dome, and tweeter on tweeter axis at 45" and corrected for microphone response, with nearfield woofer and port responses below 300Hz and 600Hz, respectively.

The overall combined frequency response of the Veritas is shown in fig.3. Here, the response below 300Hz is the combined nearfield output of the woofers and port (summed in both magnitude and phase); the response above 300Hz was taken at 45" on the tweeter axis, averaged across a 30 degrees horizontal window. The bottom end rolls off rapidly below 40Hz, with useful response down to perhaps 30Hz. There's also a broad region of increased output in the mid- and upper bass. These are near-anechoic results, but they correspond closely with the observations of the listening tests in a real room.

Fig.3 Energy Veritas v2.8, quasi-anechoic response on tweeter axis at 45" averaged across 30 degrees horizontal window and corrected for microphone response, with complex sum of nearfield woofer and port responses below 300Hz.

Higher up, the response is very linear and smooth to the top of the range, with only a small region of emphasis around 10kHz. The latter would normally tend to emphasize sibilants, but I didn't find that to be a problem in my listening. There's a dip across the range from 2-4kHz which might account for the somewhat forgiving quality I noted in my auditions, but it's small in degree—perhaps enough to sweeten the sound a bit without audibly shaving off detail.

The rise visible at about 5kHz might account for the slightly metallic flavor occasionally observed, but again, like the 2-4kHz dip, it's small enough—with similarly subtle audible effects—that such a connection must remain conjecture. The tweeter resonant peak may be seen at about 25kHz, well-damped by its notch filter.

Fig.4 shows the horizontal-response family of a vertically oriented Veritas, with any on-axis response deviations subtracted so that the on-axis response appears flat. The response remains very consistent over a wide angle—at least ±15 degrees. The vertical-response family in fig.5 indicates minimal vertical interference and lobing. At any listening height from 36" from the floor to the top of the cabinet—which includes most reasonable seating positions for most people—the response will change very little. Only very low positions—the result of sitting on the floor, perhaps—result in a significant suckout at the tweeter/midrange crossover points.

Fig.4 Energy Veritas v2.8, horizontal response family at 45", normalized to response on tweeter axis, from back to front: differences in response 90 degrees to 5 degrees off-axis; reference response; differences 5 degrees to 90 degrees off-axis.

Fig.5 Energy Veritas v2.8, vertical response family at 45", normalized to response on tweeter axis, from back to front: differences in response 15 degrees, 10 degrees, and 5 degrees above cabinet top; difference level with cabinet top; difference midway between cabinet top and tweeter axis; reference response; difference on midrange axis; difference level with top of woofer; difference on upper woofer axis; difference midway between woofers; difference on lower woofer axis, 23" from floor.

The impulse response on the tweeter axis is shown in fig.6. This is typical of a system with a high-order crossover. The ringing often seen with metal drive-units is minimal and very well damped. Fig.7 shows the Veritas's step response. This, the output of the loudspeaker with a DC voltage at its input, ideally should resemble a triangle with an initial perpendicular rise from the time axis, then a virtually straight-sloped return to that axis. (A loudspeaker is, in effect, a high-pass filter which will respond to a DC input by an instantaneous displacement, but which will not retain that displacement since, by nature, a loudspeaker cannot reproduce DC.) The response here indicates that the woofers and tweeters in the Veritas are all connected in positive polarity. The design is not time-aligned, however; the midrange output (the second peak from the left) is about 0.25ms behind that of the tweeter, with the woofer following approximately 1.25ms later.

Fig.6 Energy Veritas v2.8, impulse response on tweeter axis at 45" (5ms time window, 30kHz bandwidth).

Fig.7 Energy Veritas v2.8, step response on tweeter axis at 45" (5ms time window, 30kHz bandwidth).

Finally, the cumulative spectral-decay, or waterfall, plot is shown in fig.8. This is a very clean response, with a notable lack of pronounced resonances and only a slight amount of very-low-level treble hash. The strong damping of the 25kHz tweeter resonant peak can be seen at the far right; there's only a small rise, which is rapidly squelched.

Fig.8 Energy Veritas v2.8, cumulative spectral-decay plot at 45".

Altogether, this is a very clean set of measurements, with a well-controlled impedance characteristic, no serious resonances, and a very linear response with wide, smooth dispersion across the midrange and treble. Only the elevated mid- and upper-bass output keeps the results from being among the best we've measured.—Thomas J. Norton

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