Care Of Your Subwoofer; Protection Circuitry - Velodyne ULD-12 Owner's Manual

CARE OF YOUR SUBWOOFER
We recommend using a clean damp cloth for cleaning the cabinet. Never use detergents or abrasives on your
ULD-12.
The ULD-12 may be left on continuously without fear of long-term adverse effects. We do recommend that
you turn off the unit during extended periods of nonuse.
PROTECTION CIRCUITRY
Your ULD-12 is equipped with a special druit designed to protect the unit from damage. Either of the two con-
ditions below will power the unit down and keep it off for 5 seconds atter the fault is corrected.
1) If there is a significant drop in the line voltage.
2) If there is an input signal which momentarily exceeds the dynamic range of the unit.
TROUBLESHOOTING I SERVICE
Before seeking service for your ULD-12, please re-check all system and power connections. Also consider
the protection circuit described above; you may only need to turn the volume down slightly.
if you determine that your unit requires service, then please contact your local Velodyne dealer.
The following conditions always require service by qualified personnel:
1) If the power cord or speaker connecting cable is damaged
2) If the unit does not appear to operate normally or exhibits a marked change in performance
3) If the unit has been exposed to water
VELODYNE HGS SYSTEM
Velodyne's prime focus is in providing low distortion loudspeaker systems that impress the dedicated audio-
phile as welf as the casual listener. Velodyne developed its patented High Gain Servo (HGS) system to bring
nonlinear distortion down to unprecedented levels on its ULD-15 and ULD-18 high performance subwoofers. Your
new ULO-12 uses this same HGS technology to reproduce the music you enjoy without the excessive nonlinear
distoritons that plague conventional loudspeaker designs.
The Problem of Distortion
Nonlinear distortion is defined as any form of distortion that moves energy from one portion of the audio
frequency spectrum to another. When a single tone is applied to a nonlinear system, the result is harmonic
distortion, in which some of the energy leaves the system at integer multiples of the original input frequency_
When multiple tones are applied to the same system, intermodulation tones are produced, usually as simple
combinations of the input frequencies, Le., sums and differences of integer multiples of the applied tones. In
general, 3% nonlinear distortion is considered a reasonably small amount. This means that 3% of the total energy
leaving a loudspeaker is at frequencies other than the intended pure tone applied to the input. Our tests, however,
indicate that about 0.5% nonlinear distortion at normal listening levels must be achieved before the average
listener is truly affected by an improvement in bass response.
In the reproduction of deep bass n01es, loudspeakers suffer from a "double-whammy" when it comes to
nonlinear distortion. First, most loudspeakers have much more than even 3% THO (Total Harmonic Distortion) at
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