Review: B&W Z2 AirPlay dock Page 2
54 Hz to 20 kHz ±7.0 dB on-axis, ±4.3 dB to 16 kHz, ±8.3 dB avg 0-30°
Bass output (CEA-2010A standard)
• Ultra-low bass (20-31.5 Hz) average: NA
20 Hz NA
25 Hz NA
31.5 Hz 82.3 dB
• Low bass (40-63 Hz) average: 91.2 dB
40 Hz 85.9 dB
50 Hz 89.7 dB
63 Hz 95.3 dB
To measure the quasi-anechoic frequency response of the Z2, I set it atop a 2-meter stand and placed the microphone at a distance of 1 meter. (Quasi-anechoic measurements eliminate reflections from surrounding objects to simulate measuring in an anechoic chamber.) The microphone was placed on the same axis as the left tweeter, which is where I got the smoothest response. I then ran a ground-plane measurement at 1 meter to get the bass response. To create the graph shown here, I spliced the bass response to the 0° on-axis response (blue trace) of the left channel only, and to the average of quasi-anechoic measurements (green trace) of the left channel only taken at 0°, ±10°, ±20°, and ±30°. I used a Clio FW analyzer in MLS mode for the quasi-anechoic measurements and log chirp mode for ground plane, feeding test signals into the Z2’s 3.5mm line input. The quasi-anechoic measurements were smoothed to 1/12th octave.
The Z2’s frequency response is a little unusual in that its averaged response has more high-frequency output than the on-axis response. Regardless, the response from 200 Hz to 15 kHz—i.e., almost the entire audio range—is quite smooth. There’s a strong treble roll-off above 15 kHz, but that’s inaudible or nearly inaudible to most of us. Off-axis response is excellent, with almost no variance in the on-axis and averaged responses below 12 kHz.
When I listened to the Z2, I didn’t hear enough bass output to warrant full CEA-2010 bass output measurement, but because I did them with the A7, I went ahead and did them for the Z2. I did the measurements at 1 meter because as with most personal audio products, the Z2’s output wasn’t strong enough to do them at the usual 3 meters. Averages are calculated in pascals per CEA-2010A procedure. Bottom line is that the Z2’s bass output is much less than the class-leading A7 produces: just 91.2 dB average from 40 to 63 Hz, versus the A7’s 105.2 dB.
My MCMäxxx™ test, in which I crank up Mötley Crüe’s “Kickstart My Heart” until it sounds distorted then back it off one notch and measure the output at 1 meter, gave me a measurement of 91 dB, 6 dB short of the A7’s 97 dB.—Brent Butterworth
B&W’s Z2 AirPlay Speaker manages to combine performance with simplicity and style. And while the included dock may seem a bit retro, it does make the Z2 the perfect bedside music system and overnight charging station for your new iPhone 5.