Martin Audio – MA1400 Amplifier
E
NGLISH
9
6.5
Power consumption
There are three ways to determine the power/current consumption of the amplifier:
First, the peak current draw at full power output. Under this condition the amplifier will operate for less than 2
minutes before thermally limiting or blowing the mains fuse.
Second, the maximum expected average current under worst case program material, which is 1/3 of full power
according to the FTC-standard. At this level the music will be in the state of constant clip and is therefore the
highest power level one can obtain without completely obliterating the program material.
Lastly, the "normal operating power", as defined by EN 60065 as a measurement level for approval and testing to
this standard. The normal operating power is measured using pink noise, with an average output power equal to
1/8 of full power. The one-eighth power is the maximum volume music can be re-played without continuous
amplifier clipping, and corresponds to a headroom of 9dB's, which is very low for normal program material.
6.5.1
Calculation
The current draw can be calculated by dividing the mains input power by the mains voltage.
We recommend that you design the power distribution for at least the required current at 1/8 power, and 1/3 power
for heavy-duty demands such as concert touring and Industrial music etc.
The heat power can be calculated as follows:
If a headroom figure of 9dB is used with a 4 ohms load on each output of the amplifier. The 1/8 power per channel
is 700 / 8 = 87 watts, and the total output power = 2 x 87 = 175 watts.
The mains power consumption from the chart above is then 760 watts.
The heat power produced is the difference between the power consumption and output power;
760 - 175 = 585 watts total for the amplifier.
MA1400 HEAT POWER
1/3 POWER
1/8 POWER
1/3 POWER
1/8 POWER
1/3 POWER
1/8 POWER
WATTS
Kcal/hour
BTU/hour
8 Ohm
407
324
350
280
1390
1110
4 Ohm
683
585
590
500
2330
2000
2 Ohm
1225
963
1050
830
4180
3290
1/3 Power level = Average power with music as programme source. The amplifier driven to clip level
1/8 Power level = Normal operating power with music as programme source, 9dB headroom
Power
1/3 Power
1/8 Power
Idle
[W]
note 1
note 2
MA1400
8 ohms
2x
425
690
430
90
4 ohms
2x
700
1150
760
90
2 ohms
2x
1050
1925
1225
90
note 1
Average power with music as program source. The amplifier driven to clip level.
note 2
Normal music power with 9dB headroom, IEC standard power rating.
MAX OUTPUT POWER
MAINS INPUT POWER
All material © 2007. Martin Audio Ltd. Subject to change without notice.
