Velodyne Acoustics HGS-12X - Manual (Page 6)

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Installation
Your new Velodyne servo subwoofer provides for a number of installation
options. Read all the installation information below in order to determine
which installation option is best for your system. Remember to perform
all installation procedures with subwoofer unplugged!!!
Inputs
Your new subwoofer is equipped with line-level inputs. Use the LINE
LEVEL jacks when connecting your subwoofer to a pre-amp, signal
processor, line-level crossover, or receiver with pre-amp level outputs. If
your receiver/electronics does not have RCA type line level outputs, you
must use a high to low level adapter. Consult the dealer where you
purchased the unit for further details.
Product Features and Controls
• 12" (9.7" Piston Diameter) subwoofer with tandem 3" voice coils and
310 oz. motor
• Built-in 1000/1250 watt (RMS) high efficiency Class D amplifier
• Accelerometer based servo control system for extreme accuracy
• Adjustable (40 to 120Hz) low-pass crossover (defeatable)
• Multiple staggered low-pass crossovers; 12dB/octave initial,
48dB/octave ultimate
• Line-level (RCA) inputs and outputs
• 80 Hz high-pass crossover output
• Signal sensing auto turn on/off (defeatable)
• Variable volume control
• Selectable phase control (0° or 180°)
• Selectable subsonic filter (20Hz or 35Hz)
• Frequency response of 20Hz - 120Hz +/- 3dB
• Detachable power cord
• Anti-clipping circuit prevents over excursion and amp clipping
• Optional remote control with power, volume and mute functions
systems. Even at 1 watt, many conventional units produce several percent
distortion. Secondly, the odd order, higher harmonics are much more
offensive to the human ear than the closer 2nd harmonic.
An interesting result of this reduced distortion is that some of the bass, when
played over an extremely accurate subwoofer system, seems to actually be
missing. The truth, however, is that the "missing" bass was never there to
begin with! Distortion products of conventional woofers actually add to the
bass spectrum making it appear louder than recorded. This is due to the
additional and unwanted harmonics (distortion) of the fundamental signal.
While conventional subwoofers offer little to combat distortion products,
we at Velodyne have developed another way. . .
The Velodyne Servo-Control Solution
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The Velodyne HGS subwoofers produce sound in the same manner as
conventional loudspeakers: a cone-shaped piston is forced to move by
means of a linear motor. However, this is about the only conventional part
of the subwoofer.
We determined that conventional motors are unacceptable when called
upon to produce the amount of linear motion we desired. This inadequacy
led us to design an improved motor structure by incorporating two coils,
operating out of phase in a push-pull configuration within two magnetic gaps
& suspended by dual spiders for even greater linearity. We designed this
motor to produce over one-inch (1-1/4" to be exact) of linear motion, with
a maximum mechanical limit of 2" peak to peak. Also, with this unique
configuration, the distortion products are reduced by a factor of two over
conventional single coil structures with dramatically improved cone control.
This driver alone would result in less distortion than any other non servo
design. After optimizing every remaining part of the loudspeaker, we then
turned to the electronics.
As in our other servo products, we then incorporated closed-loop
accelerometer based servo-control of the loudspeaker. At the heart of this