Velodyne Acoustics HGS-12X The Velodyne Servo-ControlSolution, Product Features and Controls

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.

Aninterestingresultofthisreduceddistortionisthatsomeofthebass,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 beginwith!Distortionproductsofconventionalwoofersactuallyaddtothe bass spectrum making it appear louder than recorded. This is due to the additionaland 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

–––––––––––––––––––––––––––––––––––––––––––––––––––˝–––––––––

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, operatingoutofphaseinapush-pullconfigurationwithintwomagneticgaps

&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 conventionalsinglecoilstructureswithdramaticallyimprovedconecontrol. 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

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/octaveultimate

•Line-level (RCA) inputs and outputs

•80 Hz high-pass crossover output

•Signal sensing auto turn on/off (defeatable)

•Variablevolumecontrol

•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

Installation

Your new Velodyne servo subwoofer provides for a numberof 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.

continued. . .

9 ☞ 2 ☞