TEST BENCH

Frequency response (at 2 meters) Front left/right: 36 Hz to 16.1 kHz ±4.6 dB

Sensitivity (SPL at 1 meter with 2.8 volts of pink-noise input) Front left/right: 89 dB

Impedance (minimum/nominal) Front left/right: 2.3/5 ohms

Bass limits (lowest frequency and maximum SPL with limit of 10% distortion at 2 meters in a large room) Front left/right: 32 Hz at 80 dB Subwoofer: 32 Hz at 80 dB SPL 87 dB average SPL from 32 to 62 Hz 91 dB maximum SPL at 40-50 Hz Bandwidth uniformity 95%

All of the curves in the frequency-response graph are weighted to reflect how sound arrives at a listeners ears with normal speaker placement. The curve for the left/right front channels reflects response of the C7 with the speaker standing on the floor averaged over a ±30º window. Because the speaker will always be used on a floor, measurements were taken with the speaker on a floor in a large room. All measurements were taken at 2 meters, a span that emulates a typical listening distance, allows a larger speaker such as the C7 to fully integrate acoustically, and, unlike near-field measurements, incorporates front panel reflections, grille effects, and cabinet diffraction.

The C7 is a wide-radiating speaker. At ±30º its directivity remains uniform to 10 kHz, and even at ±45º off-axis directivity is uniform up to 6 kHz. The major response characteristics are a small 2 dB floor bounce centered at 190 Hz, a pair of 3-4 dB elevations centered at 450 and 3 kHz, and a gently falling treble balance above around 3 kHz. The speaker's Boost and Cut high-frequency controls simply allow about 1 dB of increase or decrease of treble above 1.5 kHz and the Boundary switch position cuts output below 300 Hz by an increasing amount to approximately 6 dB at 30 Hz. The speaker's unusually low impedance may limit use with older amplifiers. For example, impedance hovers near or below 4 ohms from 60 to 430 Hz and 5.4 ohms beyond that point up to 17 kHz.

The C7's good low-frequency performance lets it deliver bass output that's in many respects equivalent to a smaller 10-inch powered subwoofer. For this reason, I tested it as though it were a subwoofer, with mid-room placement. My main point here is that its response is dynamically pretty flat to 40 Hz, and it still delivers an honest 80 dB at 32 Hz. The SPL numbers are for a single C7 speaker; when used as a stereo pair you can estimate roughly a 3 dB increase in SPL.

- Tom Nousaine