Test Bench: Vienna Acoustics Schönberg Speaker System
In the lab
Frequency response (at 2 meters) front left/right: 53 Hz to 20 kHz ±5.6 dB center: 85 Hz to 20 kHz ±5.4 dB surround: 90 Hz to 20 kHz ±4.0 dB subwoofer: 23 to 71 Hz ±1.8 dB
Sensitivity (SPL at 1 meter with 2.8 volts of pink-noise input) front left/right: 88 dB center: 90 dB surround: 88 dB
Impedance (minimum/nominal) front left/right: 2.3/5 ohms center: 2.8/8 ohms surround: 3.1/7ohms
Bass limits (lowest frequency and maximum SPL with limit of 10% distortion at 2 meters in a large room) front left/right: 62 Hz at 88 dB center: 80 Hz at 71 dB surround: 80 Hz at 81 dB subwoofer: 32 Hz at 100 dB SPL 102 dB average SPL from 32 to 62 Hz 107 dB maximum SPL at 62 Hz bandwidth uniformity 96%
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 Schönberg tower's response with the speaker standing on the floor, averaged over a ±30-degree window with double weight at 30 degrees (the most typical listening angle). The center-channel curve reflects the Webern's response averaged over ±45 degrees, with double weight directly on-axis of the primary listener. The surround-channel curve shows the Berg's response averaged over ±60 degrees. Both the center and surround speakers were measured on a 6-foot stand, which gives anechoic results to approximately 200 Hz. All measurements except those for the subwoofer 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.
Frequency response of both the left/right and surround speakers varied widely by measurement angle and azimuth in the range above about 1 kHz. Our averaging techniques tend to underplay this, but with horizontally arrayed systems like these every listener tends to get a different sound. The Schönberg tower's response also exhibits a floor-bounce cancellation at 244 Hz, which is common with floorstanding speakers.
Even the vertically arrayed Webern center speaker has a deep, wide 1.5-kHz notch directly on-axis that grows increasingly severe at wider listening angles. All speakers have relatively low impedance near 250 Hz, but the Schönberg tower has also has a low point at the 55-Hz cabinet tuning frequency.
I measured the Rel R-305 Sub-Bass system'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 up to 3 dB greater sound-pressure level (SPL).
The R-305 has good bandwidth uniformity but lacks dynamic capability and cannot produce 25 Hz with less than 20% distortion. Frequency response is uniform across the high-level, low-level, and LFE inputs, although output via the LFE input is 2.5 dB lower when inputs are compared directly with the same input signal level. Although the Crossover control is marked at 25 Hz on one end and 100 Hz at the upper end, the true turnover frequency is 55 Hz at the lower end and 71 Hz at the top. There is also an 8-dB level difference at the bottom of the crossover rotation. As with many subwoofer systems, changes in crossover frequency also require re-balancing subwoofer level.