Speaker Systems

All measurements shown here were taken with the grilles in place.

Synchrony One
Minimum impedance: 3.44Ω at 72Hz
Nominal impedance: 4Ω
Port tuning: 36Hz (see text)
Effective bass extension (-10dB): 35Hz (open ports)
Sensitivity: 90dB/2.83V/m

The Synchrony One's impedance phase angle was benign. The speaker should be relatively easy to drive if the amplifier is comfortable with a 4Ω load.

Fig. 1: PSB Synchrony One, averaged pseudo-anechoic response, off-center in the horizontal plane, at 45° (red) and 60° (blue).

The overall response of the Synchrony One is shown in Fig. 1. The rolloff at the top end in this graph is likely the result of the grille. As for the unevenness in the low- to mid-treble, see the discussion of Fig. 2 below.

The bass performance of the One shows a rapid rolloff below 65Hz. This may be at least partially the result of test-procedure limitations. With the grilles in place, the woofers could not be as closely miked as is ideal for this measurement.

The results here are also a complex combination of the responses of the three woofers, which roll off at different frequencies, and the three ports. The usable bass response of the Synchrony One alone may be somewhat lower than the 35Hz shown above (derived from Fig. 1), but a good subwoofer is still strongly recommended to fill out this speaker's bottom octave in a home-theater system.

Fig.2: PSB Synchrony One, averaged pseudo-anechoic response at 15° above (red) and 15° below (blue) the tweeter axis.

Fig. 2 shows the same averaged horizontal front response (violet), but this time overlaid with the vertical responses taken at +15° (red) and –15° (blue). This response strongly suggests that you should be above the tweeter for optimum listening, not below it.

In fact, Fig. 2 also reveals something important about Fig. 1. The measurements for Fig. 1 were taken at tweeter height, per our normal practice. But a typical ear height with this speaker is above the tweeter, which is located below the midrange on this speaker. Note that the red curve in Fig. 2 is smoother through the midrange and mid treble than the averaged on-axis curve in Fig. 1. The red curve in Fig. 2 is, therefore, a more accurate representation of the direct response of the Synchrony One at the listener's ears. Nevertheless, the response shown in Fig. 1 does contribute to the total in-room response of the speaker, and the deviations there could be one factor in the slight tendency to brightness I heard in the low to mid treble.

Synchrony One C
Minimum impedance: 5Ω at 149Hz
Nominal impedance: 6Ω
Port tuning: 30Hz
Effective bass extension (-10dB): 48Hz (open port)
Sensitivity: 90dB/2.83V/m

Unlike the Synchrony One, the One C's impedance phase angle becomes highly capacitive in a narrow range centered at about 85Hz. But given a typical 80Hz crossover point to the subwoofer, this should cause no particular problems. The One C is a relatively straightforward load to drive.

Fig.3: PSB Synchrony One C, averaged pseudo-anechoic response, off-center in the horizontal plane, at 45° (red) and 60° (blue).

The overall response of the Synchrony One C is shown in Fig. 3. It's actually smoother than that of the One, but with a more severe high-frequency rolloff. The most notable deviation, however, is the suckout centered around 800Hz. This is most likely due to comb filtering between the two horizontally displaced woofers. The frequency range of this dip also suggests that the two woofers may be crossed over higher than the specified 500Hz, which should be low enough to prevent this sort of interaction. Fortunately, this characteristic only starts to show up as you move beyond about 20° off-axis. But such a dip should be mild or non-existent in a three-way center channel speaker in this configuration.

Fig.4: PSB Synchrony One C, averaged pseudo-anechoic response at 15° above (red) and 15° below (blue) the tweeter axis.

Fig. 4 shows the same averaged horizontal front response (violet), but here overlaid with the vertical responses taken at +15° (red) and –15° (blue). As with the One, you want your ears to be at or above the tweeter axis.

All figures: Violet curve indicates the pseudo-anechoic response on the tweeter axis, averaged across a 30° horizontal window, combined with nearfield responses of the woofers and ports. All other measurements taken at 1 meter.