Super Mini Cube: World’s Cheapest, Tiniest Audio System Page 3
IN THE LAB
Frequency response (at 1 foot) 1.3 to 20 kHz ±14 dB Bass limits (lowest frequency and maximum SPL with limit of 10% distortion at 2 meters in a large room) (surely you jest)
Maximum full-band output approx. 78 dB at 0.5 meters The frequency-response graph is weighted to reflect how sound arrives at a listener's ears with normal speaker placement (whatever that is for a product like this). Measurements were made at 1 foot, which with a system this small is adequate to include full effects of cabinet diffraction, and was also necessary to achieve adequate output for measurement. Measurements were made on a 6-foot stand, which delivered quasi-anechoic results to far below the Super Mini Cube's useful range. Normally, I scale speaker measurements so that the level at 1 kHz is 0 dB. However, that was impossible with the Super Mini Cube, because it doesn't play that low. I ended up using 2.5 kHz as the 0 dB point, just so I could fit the frequency response curve into Sound & Vision's standard chart.
The Super Mini Cube is, in essence, a cheap tweeter. Its response starts to plunge below 3 kHz. The only range in which the response is fairly smooth is between 4 and 12 kHz. The manufacturer rates low-frequency extension at 600 Hz, but while there is some output at that frequency, it's heavily attenuated and extremely distorted.
At 1 kHz-the standard reference frequency for audio measurements-the lowest total harmonic distortion I was able to achieve was 19.8%. Turning up the volume on the source increased THD further, often well above 50%. At higher frequencies and low levels, it was better; minimum THD was 1.8% at 2 kHz and 0.5% at 4 kHz. Those numbers might seem high, but they're not unusual in the speaker world.
By the way, the output is rated at 0.8 watts, but the manufacturer seems to have come up with that number by multiplying the battery's voltage by its maximum current. Using the RMS calculation commonly employed for rating audio amplifiers, the output is more like 0.2 watts.
To measure maximum acoustical output, I played a variety of music through the Super Mini Cube, turned the level down to the point where distortion was low enough to tolerate, then measured the SPL at 1.5 meters, which I consider a typical listening distance for a device like this. Jazz and lighter music, such as Wes Montgomery and Joni Mitchell, distorted badly at levels above about 65 dB. Heavily compressed rock, such as Rammstein and Mötley Crüe, came through a little clearer, peaking out at about 78 dB. (And probably the ample distortion in those recordings made the Super Mini Cube's added distortion subjectively less annoying.) These levels may not seem loud, but for light background music they're quite adequate.
After extensive laboratory evaluation, I can confidently state that the Super Mini Cube is the finest 1-inch-cube audio system I've ever measured.