Surround Sound Speaker Systems
- Written by Ross Jones
- Published on 23 March 2009
On the Bench
Remember my comment about the SB-12â€™s rated frequency response being flat to 20Hz from a small, sealed subwoofer? Take a look at this sine wave measurement of 20 Hz at 100 dB: 1.27% THD+N. Notice how the first harmonic (at 40Hz) is a full 35dB quieter than the fundamental.
Here is THD+N vs frequency. Distortion never goes above 4% even at 10Hz, and is under 2% for most of the low bass region.
Frequency response at 1 foot (red), 1 meter (blue) and two meters (yellow).
The M7, at the low end of its rated frequency response, produces 1.4% THD+N.
[insert 80 Hz THD + N]Fig 8
At 1hHz, distortion is 0.47%.
And at 10kHz, 0.376% THD+N. These are all excellent measurements.
THD+N versus frequency response:
White noise at two meters, basically in-room response (without any room EQ added).
As noted, the M7 is rated at 4 Ohms impedance. Electrical phase is within 70 degrees across the spectrum.