DB Drive Speed Series Amplifier SPA SPA90.2 - Manual (Page 7)

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A
DJUSTMENTS AND SETTINGS
The “Speed Series” amplifiers are equipped with built-in variable crossover networks allow-
ing you to select the crossover mode (i.e. Low-Pass/Full/High-Pass or On/Off) and the
desired crossover point. For example if you wish to drive a pair of subwoofers, you can
select the “Low Pass” setting on the amplifier to filter out high frequencies. This will send
only low frequencies to your subwoofers (see example settings below). The crossover point
should be determined by the speakers operating range. Please refer to speaker manufac-
tures recommended crossover point.
F
INE TUNE THE SYSTEM
Fine tune the amplifier’s input sensitivity
The gain sensitivity control for the “Speed Series” amplifier is located on the side panel.
This gain control has been included to allow adjustment to properly match the output of the
radio. This is one of the most misunderstood adjustments. By rotating the control in the
clockwise direction, the amplifier’s input will become more sensitive and the music will play
louder. 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. Ideally, to properly level
match the system the goal is to achieve maximum output from the amplifier without distor-
tion at about ¾ of the volume control.
To determine if the amplifier’s gain is set properly, turn the system on and slowly increase
the volume control. You should be able to use about ¾ volume before the system gets loud
but not distorting. It is very important when making these adjustments that you do not over
drive the speakers (at point of distortion) this will cause permanent damage to the speakers.
If you are unable to achieve ¾ volume before distortion you will need to adjust gain control
(in this case you would reduce the gain). The gain controls should be adjusted very slowly.
It may help to have another person to assist you by adjusting the gain controls while you
listen for distortion.
Input Level
bass
boost
input
level
freq
0dB 18dB
bass
boost
0dB 18dB 60Hz 400Hz
freq
60Hz 400Hz min max
input
level
min max
x-over
low full high
x-over
low full high
input
ch 1 ch 3
ch 2 ch 4
remote
spa150.4
classAB 4 channel amplifier
Adjust the frequency to the
desired point for speakers 1 & 2.
Adjust the frequency to the
desired point for speakers 3 & 4.
Filter selection for channel 1 & 2 Filter selection for channel 3 & 4
Bass Boost @ 45Hz
*0~18dB Channels 3 & 4
Only in Lowpass
Bass Boost @ 45Hz
*0~18dB Channels 1 & 2
Only in Lowpass
Min Max