User manual VELODYNE HGS-12X REV A

[. . . ] HGS-12X Owner's Manual High Gain Servo-Controlled Audio/Video Subwoofer System IMPORTANT SAFETY INSTRUCTIONS CAUTION RISK OF ELECTRIC SHOCK DO NOT OPEN Caution: To reduce the risk of electric shock, do not remove cover (or back). The lighting flash with arrowhead symbol is intended to alert the user to the presence of uninsulated "dangerous voltage" within the product's enclosure that may be of sufficient magnitude to constitute a risk of electric shock to persons. The exclamation point symbol is intended to alert the user to the presence of important operating and maintenance (servicing) instructions in the literature accompanying the subwoofer. 1. Read Instructions -- All safety and operating instructions should be read before the subwoofer is operated. [. . . ] . 2 Volume control This control allows you to balance the output from the subwoofer to the main speakers/amplifier in your system. This control should be set to achieve similar output level from both the main speakers and subwoofer when listening to music. A good starting point for the volume control is 4 or 5 dots from minimum. Low-pass crossover - 40 to 120Hz The line-level inputs sum the left and right channels together, with the resulting signal passing through an adjustable low-pass crossover before being amplified. The crossover control allows you to adjust the upper limit of the subwoofer's frequency response from 40 to 120Hz. The subwoofer's output will be reduced above the frequency you set this control to. You should set the crossover frequency to obtain a smooth and seamless transition from the subwoofer to the main speakers in your system. If your main speakers are smaller units with limited low frequency output, you may wish to choose a higher frequency (such as 100-120Hz) than you would with larger speakers which have greater low frequency output. With larger speakers, you might start with this control set lower, such as 80Hz. A bypass switch is also provided if you wish to use an external crossover. If you are not using an external crossover, we recommend that you use the one provided within the unit for optimum performance!Phase adjustment - 0°/180° This control allows you the "reverse" the phase of the subwoofer's output signal 180° to correct for any possible mismatch and resulting cancellation between the subwoofer and your main speakers/amplifier. Then move the switch from one position to the other and listen for a change in low frequency output. The correct position will have a greater amount of apparent low frequency output. Subsonic - 20Hz/35Hz This adjustment alters the low frequency limit of the subwoofer. In certain movie theater installations which suggest that the extreme low bass be limited, move the switch position to 35Hz and the response will be attenuated below this frequency. 3 Crossover switch - In/Out This switch allows the electronic crossover circuitry to be removed from the signal path. This is preferable in certain installations which route the signal through external processors with a crossover circuit of their own, such as the new digital units. For all other installations which do not have a separate electronic crossover we recommend you leave the internal crossover IN to provide optimum performance. Auto turn on function With this function in the "auto" position, your subwoofer can be safely left with the main power switch on continuously. The subwoofer will turn itself on automatically when an audio signal is present. If no signal is present for approximately 15 minutes, the unit will switch to standby mode. [. . . ] To provide the power for driving this massive loudspeaker, we incorporated an extremely efficient Class D switching amplifier. This new amplifier features our patent pending energy recovery circuit design which drastically reduces wasted energy (heat) as compared to traditional switching designs. One that is capable of running cool to the touch and providing 1000 or 1250 watts (RMS - depending on the model) of power!At typical listening levels, the HGSX produces less than 1% harmonic distortion with input signals extending to 20Hz. [. . . ]