Phase Technology Premier Collection surround speaker system Measurements
The PC 9.1's sensitivity is approximately 88dB/W/m, and its ported cabinet is tuned to about 30Hz. I would rate its nominal impedance at a conservative 4ohms. The impedance bottoms out at 2.64ohms at 123Hz and remains below 4ohms from 80 to 630Hz. Because most program material demands from a system more in this region than in any other, I consider the PC 9.1 a moderately challenging load to drive and would not team it with a receiver or amplifier not comfortably rated to handle loads of 4ohms.
The PC 9.1's pseudo-anechoic response at tweeter height, averaged over a 30° forward horizontal angle and combined with the nearfield responses of the woofers and port, is shown in Fig.1 (violet). The useful bass extends down to about 25Hz (-10dB relative to the output at 1kHz). Though the on-axis average is smooth from about 1kHz to the top of the range, there is a significant dip centered at about 300Hz and extending over the upper bass and midrange. This may or may not be audible as a leaning-out of the sound, depending on the room. If your room has an emphasis at around 300Hz—not a rare situation—the dip in the speaker and the peak in the room may partially cancel each other out, at least for some seating locations. The response is less smooth off-axis, but the 45° response holds up reasonably well to 12kHz, though at a reduced level.
Fig.2 again shows the PC 9.1's averaged horizontal front response (violet), plus the vertical responses taken at +15° (red) and -15° (blue) relative to the tweeter. Though the responses are very similar, given the choice, I'd sit on or slightly above the tweeter axis.
The center-channel PC 3.l's cabinet is tuned to about 36Hz. I would rate its nominal impedance at 5ohms, with a minimum of 2.72ohms at 154Hz. The impedance remains below 4ohms from 100 to 430Hz. I'd use the PC 3.1 as I would the PC 9.1: with a well-designed amplifier capable of driving 4ohms without complaint. The PC 3.1's sensitivity measured approximately 88dB/W/m.
The PC 3.1's measured front horizontal response, taken on the tweeter axis and averaged in the same manner as described above for the PC 9.1, is shown in Fig.3(violet). The useful bass extension is about 35Hz (-10dB). The on-axis response is smooth, but while the 3.1 is a desirable three-way design, it exhibits the same sort of suckout off-axis that we've seen in many other horizontally configured speakers. The suckout here simply occurs at a lower frequency.
The PC 3.1's ±15° vertical off-axis performance (Fig.4) is excellent; within the limits measured, the vertical listening position is not critical.
Altogether, this is a reasonably good set of measurements, the main limitation being the PC 3.1's off-axis performance at wide angles, a shortcoming it shares with many other center-channel speakers.—Thomas J. Norton