Test Bench: Sunfire Cinema Ribbon Loudspeakers
In the lab
Frequency response (at 2 meters) front left/right: 101 Hz to 20 kHz ±5 dB center: 97 Hz to 16.4 kHz ±4 dB surround: 101 Hz to 20 kHz ±5 dB subwoofer: 31 to 56 Hz ±1.5 dB
Sensitivity (SPL at 1 meter with 2.8 volts of pink-noise input) front left/right/surround: 84 dB center: 84 dB
Impedance (minimum/nominal) front left/right/center: 5.7 / 13 ohms center: 5 / 15 ohms
Bass limits (lowest frequency and maximum SPL with limit of 10% distortion at 2 meters in a large room) front left/right/surround: 80 Hz at 81 dB center: 80 Hz at 82 dB subwoofer: 32 Hz at 93 dB SPL 100 dB average SPL from 32 to 62 Hz 106 dB maximum SPL at 50 Hz
All of the curves in the frequency-response graph are weighted to reflect how sound arrives at a listener's ears with normal speaker placement. The curve for the left/right front channels reflects the CRM-2's response averaged over a ±30° window. The center-channel curve reflects a horizontally arrayed CRM-2C's response averaged over ±45°, with double weight directly on-axis of the primary listener. The surround-channel curve shows the CRM-2's response averaged over ±60°. All acoustical measurements were taken at a full 2 meters distance and thus take into account true acoustical summation of individual radiating elements, front-panel reflections, and cabinet diffraction.
Because of the radical differences in directivity between their planar-magnetic tweeters and moving-coil woofers, both the CRM-2 and the CRM-2C have response that varies widely with listening angle, which tends to be obscured by our averaging techniques. An overall depression from 400 Hz to 4 kHz shows in every trace for the CRM-2, however, and the irregularities seen in the averaged trace for the CRM-2C are more severe off-axis. I made the basic measurements for both models with their boundary-compensation switches at the Room setting. With the switch set to the Wall position, the CRM-2's output is reduced by 2.3 dB below 400 Hz and the CRM-2C's by 4.9 dB.
I measured the True Subwoofer Super Junior's frequency response 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 up to 3 dB greater sound-pressure level (SPL). Frequency response was taken ground-plane at 0.5 meter, which accommodates true acoustical summation of individual radiating elements. I tested bass limits with a second True Subwoofer Super Junior stacked atop the first to measure their summed output, reflecting the use of two subwoofers in Dan Kumin's subjective evaluation.
Like other tiny subwoofers, the Super Junior has limited extension but fairly smart output capability at the top of its operating range (50 Hz and above). It achieved 106 dB maximum SPL at 50 Hz and went as low as 32 Hz at 93 dB before exceeding our 10% distortion limits.
The Crossover control is marked from Bypass to 30 Hz, but the Super Junior's operating range extends only from 31 to 56 Hz even when the control is set to Bypass. When the control is set to 30 Hz, the actual acoustic operating range is 31 to 42 Hz. When the level control is set to +15, actual volume increases by 2.1 dB.