Precision Power DCX 300.4 - Manual (Page 11)

CURRENT DRAW
The following is a basic formula to be used as a guide to determine
current draw. Your new
DCX amplifier is more efficient than most
other amplifiers. This formula is to be used as a guideline. Using wire
of a larger gauge can only improve the current transfer of your
system. Do NOT use smaller wire gauge.
Total RMS output X 1.5 = Total Input Wattage
Total Input Wattage = Current Draw (in Amps)
Supply Voltage
Example: A DCX amplifier has two channels at 250 watts per
channel RMS rating into 4 ohms (250X2 = 500 watts).
You would use the formula in the following way:
500 W X 1.5 = 750 watts
750W = 62.5 Amps total current draw
12V
If the same amplifier is driven into a 2 ohm stereo or 4 ohm mono
load, double its 4 ohm RMS rating. All
DCX amplifiers will effectively
double their power at this load.
500W X 1.5 X2 = 1500 watts
1500W = 125 Amps total current draw
12V
If you are using more than one amplifier, add up the total current
draw for all of them and choose the appropriate gauge based on the
grand total.
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