In the lab
Frequency response (at 2 meters)
front left/right: 36 Hz to 17.7 kHz ±5.7 dB
center: 75 Hz to 18.2 kHz ±5.2 dB
surround: 77 Hz to 16.6 kHz ±5.2 dB
subwoofer: 27 to 119 Hz ±2.4 dB
Sensitivity (SPL at 1 meter with 2.8 volts of pink-noise input)
front left/right: 86 dB
center: 87 dB
surround: 85 dB
front left/right: 3.8/7 ohms
center: 5.1/8 ohms
surround: 4.1/14 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 75 dB
center: 80 Hz at 95 dB
surround: 62 Hz at 74 dB
subwoofer: 20 Hz at 95 dB SPL
109 dB average SPL from 25 to 62 Hz
112 dB maximum SPL at 62 Hz
bandwidth uniformity 97%
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 the GT1 tower's response with the speaker standing on the floor, averaged over a ±30° window, with double weight at 30° (the most typical listening angle). The center-channel curve reflects the GC1's response averaged over ±45°, with double weight directly on-axis of the primary listener. The surround-channel curve shows the GB1's response averaged over ±60°.
I took the measurements for the GC1 and GB1 with the speakers mounted on a 6-foot stand, which gives anechoic results to approximately 200 Hz. Except for subwoofers, 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 and cabinet diffraction.
Tower, Center, and Surrounds
Frequency balance for the GT1, GB1, and GC1 slopes gently (just under 1 dB per octave) downward as frequency increases. They all also share response irregularities beginning at 700 Hz and exhibit more exaggerated narrow peaks and valleys above 10 kHz. The latter can be ameliorated, but not fully cured, by removing the grilles. The GT1 also exhibits the common notch (300 Hz) of floorstanding speakers, attributable to interference from the floor bounce. For the CG1 center-channel speaker, off-axis lobing begins as soon as the microphone is moved off-center and becomes severe at wider listening angles.
I measured the SubSeries 6i 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 SubSeries 6i proved to have superlative dynamic capability, among the best I've seen in recent times. It puts out deep (20 Hz) and uniform output, delivering 108 dB SPL or greater from 32 Hz upward. Although the crossover is specified to cover 50 to 150 Hz, its actual acoustic cutoffs range from 43 to 119 Hz. There is virtually no interaction between the crossover-frequency setting and level, however. When the crossover is bypassed, the 6i's upper-frequency bandwidth extends to 134 Hz.
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