DB Drive SPA150.4, SPA90.4 Input Level, Adjustments And Settings, Fine Tune The System, Min Max

ADJUSTMENTS 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.

Filter selection for channel 1 & 2		Filter selection for channel 3 & 4
Adjust the frequency to the			Adjust the frequency to the
desired point for speakers 1 & 2.			desired point for speakers 3 & 4.
Bass Boost @ 45Hz			Bass Boost @ 45Hz
			*0~18dB Channels 3 & 4
*0~18dB Channels 1 & 2
			Only in Lowpass
Only in Lowpass
	input		remote
	ch 1	ch 3
x-over			x-over
low full high		low full high
0dB 18dB 60Hz 400Hz	min max	min max	60Hz 400Hz 0dB 18dB
bass freq	input	input	freq bass
boost	level	level	boost
	ch 2	ch 4	spa150.4
			classAB 4 channel amplifier

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FINE 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

Min Max

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