Test Report: SVS Ultra Tower Surround Speaker System Page 3
Extended Test Bench
• tower 43 Hz to 20 kHz ±2.9 dB avg. 0°-30°, ±3.4 dB on-axis
• center 58 Hz to 20 kHz ±2.6 dB avg. 0°-30°, ±3.3 dB on-axis
• surround 45 Hz to 20 kHz ±5.7 dB avg. 0°-60°, ±5.3 dB on-axis
Sensitivity (SPL at 1 meter/1 watt, avg. 300 Hz to 10 kHz)
• tower 87.1 dB
• center 85.5 dB
• surround 80.1 dB
• tower 3.0/5 ohms
• center 2.9/4 ohms
• surround (bipole mode) 2.9/4 ohms
• surround (dual mode) 6.1/8 ohms
Bass output, tower (CEA-2010A standard)
• Ultra-low bass (20-31.5 Hz) average: 105.3 dB
20 Hz 85.6 dB
25 Hz 97.6 dB
31.5 Hz 113.2 dB
• Low bass (40-63 Hz) average: 121.4 dB
40 Hz 119.1 dB
50 Hz 119.8 dB
63 Hz 124.3 dB
• center 105.5 dB at 40 Hz
• surround 96.0 dB at 40 Hz
I measured the frequency response of the Ultra series speakers using quasi-anechoic technique to remove the effects of reflections from nearby objects. I measured the Ultra Tower sitting directly on my measurement turntable, the Ultra Center placed atop a 2-meter-high stand, and the Ultra Surround attached to a 2-by-4-foot plywood baffle with foam around its edges to minimize diffraction from the baffle (this simulated on-wall mounting). In all cases, the microphone was placed at a distance of 2 meters, in order to capture the outputs of all drivers as well as the contributions of cabinet diffraction. I positioned the microphone directly in front of the tweeters, then adjusted the mike position slightly to get the flattest response. The curves you see in the chart represent the average of responses at 0°, ±10°, ±20°, and ±30° for the Ultra Tower and Ultra Center, and 0°, ±15°, ±30°, ±45°, and ±60° for the Ultra Surround. Except as noted, the quasi-anechoic measurements were made without grilles and smoothed to 1/12th octave. Bass response of all speakers was measured using close-miking technique, with the mike positioned about 6mm from each woofer and port. These measurements were scaled appropriately, then summed. I confirmed the results by taking ground plane measurements, with the mike on the ground 2 meters from the speaker. The bass response curves were spliced to the quasi-anechoic measurements at 220 Hz for the Ultra Tower and Center, and 120 Hz for the Surround. Results are normalized to 0 dB at 1 kHz. All frequency response measurements were made with a Clio FW audio analyzer then imported into a LinearX LMS analyzer for post-processing.
The Tower and Center both measure very well — better than the ±3.0-dB figure that’s considered by many to be a standard for a high-quality speaker. Unusually, they measure flatter in the averaged 0°-30° response than they do on-axis. The Tower has a slight downward tilt in its tonal balance, but both are generally very smooth. With both speakers, off-axis response is almost shockingly smooth, with no significant dips appearing even at ±60° off-axis. The grilles have almost no measurable effect — up or down by a dB here or there at frequencies above 3 kHz, but only in narrow bands.
It’s harder to know what to make of the surround speaker’s measurements, although the rather extreme-looking downward tilt in the tonal balance is typical of what I’ve measured from multipolar on-wall surround speakers. Measured right on the axis of one tweeter, with the speaker on a stand, the tonal balance measures much flatter (thus explaining why the Surround seemed to match the Tower so well), even though there are still major frequency response anomalies caused by diffraction.
For the Tower, minimum impedance is 3.0 ohms at 79 Hz with a phase angle of –1°. For the Center, it’s 2.9 ohms at 89 Hz/–6°. For the Surround, it’s 2.9 ohms at 235 Hz/–1° in bipole mode, 6.1 ohms at 197 Hz/–4° in dual mode. Even though quasi-anechoic sensitivity (measured on-axis outdoors, average output from 300 Hz to 10 kHz at 1 meter with a 2.83-volt RMS signal) is above average for the Tower (and you can tack on another 3 dB or so for in-room sensitivity), these impedance figures are low enough that I recommend using these speakers with a higher-end A/V receiver or a separate amp.
CEA-2010A output measurements for the Tower were taken at 3 meters, then scaled so that they are equivalent to 1-meter results. Averages are calculated in pascals. The figures shown here are actually lower than what the speaker is capable of, because even with the output of my M-Audio USB interface set to maximum, the output from my 200-watt Outlaw Model 2200 amplifier was inadequate to drive the speaker past the CEA-2010 distortion thresholds at the 63-, 50-, and 40-Hz measurement points. At 63 Hz, the highest level of any distortion harmonic was –22 dB below the fundamental, for the 2nd harmonic. For 50 Hz, it was –18 dB/3rd harmonic, and for 40 Hz it was –20 dB/3rd harmonic.
Got all that? Well, here’s what you really need to know: A single Ultra Tower, driven by a 200-watt amp, puts out about as much bass as a very good 12-inch subwoofer. Figure on another +6 dB or so for two Ultra Towers. However, the output fell rapidly below the 31.5-Hz measurement point. — B.B.