In the lab
Frequency response (at 2 meters)
front left/right: 70 Hz to 20 kHz ±5.4 dB
center: 97 Hz to 20 kHz ±3.3 dB
surround: 82 Hz to 16.1 kHz ±7.3 dB
subwoofer: 43 to 118 Hz ±1.8 dB
Sensitivity (SPL at 1 meter with 2.8 volts of pink-noise input)
front left/right: 90 dB
center: 91 dB
surround: 84 dB
Impedance (minimum/nominal)
front left/right: 3.8/8 ohms
center: 3.9/8 ohms
surround: 3.2/6 ohms
Bass limits (lowest frequency and maximum SPL with limit of 10% distortion at 2 meters in a large room)
front left/right: 40 Hz at 82 dB
center: 80 Hz at 92 dB
surround: 80 Hz at 82 dB
subwoofer: 20 Hz at 81 dB SPL
106 dB average SPL from 25 to 62 Hz
112 dB maximum SPL at 62 Hz
All of the curves in the frequency-response graph are weighted to reflect how sound arrives at a listeners ears with normal speaker placement. The curve for the left/right front channel tower speaker reflects the Millenia 300's response averaged over a ±30° window (the most typical listening angle) with the speaker standing on the floor. The center-channel curve reflects the response of a horizontally arrayed Millenia 30 averaged over ±45°, with double weight directly on-axis of the primary listener. The surround-channel curve shows the ADP-590's response averaged over ±60°. I took the measurements at a full 2 meters, ensuring that the effects of front-panel reflections cabinet diffraction are included and that all driver outputs are fully integrated acoustically.
TOWERS, CENTER, & SURROUNDS
The Millenia 300 Tower has tightly controlled directivity, but a 2.5-dB floor-bounce notch in the upper bass (typical for floorstanding speakers), a narrow 7-dB dip at 14 kHz, and a fair degree of roughness above 2 kHz were all evident in frequency-response measurements. The 14-kHz dip disappears when the grille is removed.
The Millenia 30, used horizontally as a center-channel speaker, shows flat response up to 700 Hz followed by a 2.5-dB depression from there to 4 kHz and a fair degree of peakiness above that frequency. The system's output exhibits no lobing up to ±22° off-axis, although at very wide radiating angles acute lobing develops. The ADP-590 dipole, meanwhile, shows the highly diffuse radiating pattern considered normal and useful for dipolar surround speakers.
SUBWOOFER
I measured the Seismic 12a subwoofer's bass limits with it set to maximum bandwidth and placed in the optimal corner of a 7,500-cubic-foot room. In a smaller room users can expect 2 to 3 Hz deeper extension and as much as 3 dB greater sound-pressure level (SPL).
The Sesimic 12a has excellent output capability, delivering 108 dB SPL or more from 25 Hz up. It produced a true 20-Hz signal within our 10% distortion limit, with 81 dB output, and hit a maximum SPL of 112 dB at 62 Hz.
Although the crossover control's range is marked at 35 to 150 Hz, its actual operating range is 45 to 118 Hz, with a 65-Hz high-frequency cutoff at the 12-o'clock position. The low-frequency -3-dB point also varies slightly according to the crossover-frequency setting, from 43 Hz at the wide-open position to 19 Hz at the lowest and 33 Hz at 12 o'clock. There's no frequency/level interaction over the top half of the control's rotation and just a moderate 3- to 4-dB level change at the bottom of the dial. The Bass Contour control adds 6 dB at 65 Hz.
