audio dimensions
AUDIO DIMENSIONS, Inc.
The System 3 speaker systems, from Harold Beveridge, are probably the most visually pleasing speakers ever offered. Furthermore, they are among the best sounding speakers available at any price.
A member of the ADI staff bought a pair for his own system, and has visited several other System 3 owners to combine their user information with his own. The results are impressive. As the data shows, published performance is very close to the performance measured in the listening room.
| Specifications | Published | Measured | |
| Frequency response |
27-20 kHz +/- 3 dB over a 30-100 Hz +/- 5 dB, a horizontal polar pattern of 180 degrees |
30-100 Hz +/-5 dB 100-1000 Hz +/-1.5 dB 1k-20k Hz +/-1.0 dB |
|
| Harmonic distortion | Less than 1% at 90 dB SPL 1.5% measured at 3.3 meters | 1.5% below 200 Hz; less than .5% above | |
| Sound Pressure Level | 110 dB peaks | 113 dB peaks, 107 dB sustained (multi-amped) | |
| Crossover | 200 Hz, 18 dB/octave | same | |
| Impedance | Nominally 9 (may reach 2 ohms) | 3-9 ohms from 30 Hz to 20 kHz. Above that frequency, Z tends to drop to 2 ohms | |
| Amp requirements | Min. 50 w/ch - max. 300 w/ch | recommend 200w or more, with amp capable of driving 10 mfd. load |
With the exception of the impedance (not a problem with sufficiently stable amplifiers), the Beveridge System 3 measured better than any other speaker we've seen. These cylinders can produce a more uniform and coherent wavefront than anything else we've measured, and are less depended upon room acoustics than a more conventional speaker.
Modifications
We found the wood cylinder to be insufficiently damped. The addition of mass, in the form of automobile undercoating mastic applied to the interior surface of the cylinder, substantially improves sound below 500 Hz. About 20# per pair is recommended.
Cables
The speaker works best with low DCR wiring; 10 gauge stranded is recommended. The optimum cable for the System 3 is probably Mogami, and the slight added capacitance should pose no additional problems for any amplifier stable enough to handle these speakers under any conditions.