USING SUBSONIC FILTER AND PHASE CONTROL
Using the Subsonic Filter.
Subsonic
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20 
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Models HA1000,HA700M, and HA1000M are equipped with a variable 20~50Hz subsonic filter. This filter avoids the reproduction of inaudible low frequencies on the amplifier which could damage the subwoofers because they can generate over- displacement of the subwoofer cone. You would want to set the frequency point where you want the filter not to produce frequencies below that point. Generally, human ears cannot hear low frequencies below 20 Hz.
Using the Phase Control.
Phase
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Mono subwoofer amplifier models, HA700M & HA1000M are equipped with acontinuously adjustable phase lag control on subwoofer(s) from0 to 180 degrees. This control helps to align the phase shift of a subwoofer for a smooth blending, without canceling the bass fromother speakers or subwoofer(s).
SETTING THE GAIN
Fine tune the amplifier's input sensitivity.
The gain control has been included to allow adjustment to properly match the signal output of the radio. This is one of the most misunderstood adjustments. This is not a volume control and you will not get more power out of the amplifier in the maximum position!
It may seem to deliver more output, but actually the system is only Playing louder faster as you turn the volume control on the radio.
By rotating the control in the clockwise direction, the amplifier's input will become more sensitive and the music will play louder. Ideally, to properly level match the system the goal is to achieve maximum output from the amplifier without distortion at about 3/4 of the radio volume control.
To properly set the gain, start by setting the gain to its minimum position and turn the main radio volume up to 3/4 of maximum volume control. Then slowly raise the amp gain control until the system gets loud but before the point of distortion. It is very important when making these adjustments that you do not over drive the speakers that may be permanently damaged. The gain control should be adjusted very slowly. It may help to have another person assist you by adjusting the gain control while you listen for distortion.
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