Test Bench: Focal Chorus Home Theater Speaker System
In the lab
Frequency response (at 2 meters) front left/right: 53 Hz to 20 kHz ±4.7 dB center: 86 Hz to 20 kHz ±5.7 dB surround: 94 Hz to 20 kHz ±3.8 dB subwoofer: 44 to 108 Hz ±2.1 dB
Sensitivity (SPL at 1 meter with 2.8 volts of pink-noise input) front left/right: 90 dB center: 89 dB surround: 91 dB
Impedance (minimum/nominal) front left/right: 3.2/10 ohms center: 4.9/10 ohms surround: 4.0/8ohms
Bass limits (lowest frequency and maximum SPL with limit of 10% distortion at 2 meters in a large room) front left/right: 40 Hz at 100 dB center: 80 Hz at 100 dB surround: 80 Hz at 85 dB subwoofer: 32 Hz at 89 dB SPL 101 dB average SPL from 32 to 62 Hz 112 dB maximum SPL at 62 Hz bandwidth uniformity 89%
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 826V tower's response with the speaker standing on the floor, averaged over a ±30º window. The center-channel curve reflects the CC 800V's response averaged over ±45º, with double weight directly on-axis of the primary listener. The surround-channel curve shows the SR 800V's response averaged over ±60 º. The center and surround speakers were measured on a 6-foot stand, which gives anechoic results to approximately 200 Hz. Except for the subwoofer, all measurements are taken at a full 2 meters, which emulates a typical listening distance, allows the outputs of large speakers to fully integrate acoustically, and, unlike near-field measurements, fully includes front-panel reflections, grille effects, and cabinet diffraction.
Towers & Satellites
Measurements for the floorstanding 826V showed a moderate 3-dB floor bounce notch centered at 274 Hz, followed by an overall ragged response featuring depressions with a maximum depth of about 2 to 3 dB between 400 and 800 Hz and 4 and 8 kHz. These were intermixed with elevations of up to 4 to 5 dB in the midrange (between 1.5 and 3 kHz) and upper treble (11 to 16 kHz).
The CC 800V center channel has slowly downsloping response from its effective low-frequency limit (about 85 Hz) up to 3 kHz, where it measured -3 dB. Above 3 kHz, response was marked by fairly extreme but narrow ripples on the order of ±6 dB. Our averaging techniques understate the off-axis lobing that begins at ±15º and becomes radical at wider listening angles. (At 2 kHz, the speaker measured -10 dB at ±22.5º off-axis and -34 dB at ±45º.)
The SR 800V surround's response exhibits characteristics common to bipolar speakers, with more irregularities directly on axis. But this model has significant response ripples above 800 Hz at every radiating angle.
I measured the SW 800V subwoofer's bass limits 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 as much as 3 dB greater sound-pressure level (SPL).
The SW 800V subwoofer has limited bass extension, and though it can generate 109 to 112 dB SPL at 50 and 62 Hz, dynamic capability falls off rapidly below 50 Hz (approximately 30 dB per octave).
Though the crossover control dial is marked from 40 to 180 Hz, its actual range is 70 to 108 Hz. There is a large interaction with subwoofer level over the lower half of the crossover control's operating range, with output measuring -13 dB when the crossover control was set to its low end limit of 40 Hz. Users should be prepared to reset the level control whenever they make crossover adjustments.