long-term current draw. Read more about the AFS limiter under “Protection” on page
16
. There is also a
Technical Note on our website
www.labgruppen.com
: AFS limiting and power consumption.
It is more useful to state the
current draw
in different loads and output power levels. These figures can
be found on the specification sheet. The current draw is measured in Ampere rms. This figure
corresponds to the minimum value of the mains fuse needed.
We recommend you to design the power distribution at least for the current at 1/8 power, and for 1/3
power for heavy-duty demands like discotheques, etc.
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.
Last
, the "regular operating power" as defined by the safety standard IEC 65/ANSI/UL 6500 and used
by a majority of safety agencies. The regular operating power is measured by using pink noise, and with
an average output power equal to 1/8 of full power. The one eighth of the total power is as loud as you
can play music while making some attempt to avoid obvious clipping. It also corresponds to a headroom
of 9dB, which is very low for regular audio program.
able 3
SKTKN= `~äÅìä~íáçå=
e calculated as in the following example:
4 ohms load on an amplifier
tts, and
to the chart above is then 1975 watts. This chart shows the active
he
heat power produced
is the difference between the power consumption and output power:
roduced in watts, in kcal per hour, and also in BTU per hour.
he
efficiency
can also be calculated, it being the output-power divided by the input-power:
Power*
AFS activated
1/3 Power
1/8 Power
Idle
[W]
[W]
**
***
fP 6400
8 ohms
2x
1300
1300
1230
575
105
4 ohms
2x
2300
1450
1975
900
105
2 ohms
2x
3200
1850
2950
1290
105
* = Will be reduced by AFS limiter.
** = Average power with music as program source. The amplifier driven to clip level.
*** = Regular music power with 9dB headroom, IEC standard power rating.
MAINS INPUT POWER
MAX OUTPUT POWER
T
The
heat power
can b
We consider a headroom of at least 5dB (1/3 of full power) and a
producing 2300 watts per channel. The 1/3 power per channel is accordingly 2300 / 3 = 767 wa
total output 2 x 767 = 1534 watts.
The power consumption according
power consumption of the amplifier with different loads and power levels.
T
1975 - 1534 = 441 watts per amplifier.
The chart below shows the heat power p
1/3 Power* 1/8 Power** 1/3 Power* 1/8 Power** 1/3 Power* 1/8 Power**
[W]
[W]
kcal / h
kcal / h
BTU / h
BTU / h
fP 6400
8 ohms
363
250
310
220
1240
850
4 ohms
442
325
380
280
1510
1110
2 ohms
817
490
700
420
2790
1670
* = Average power with music as program source. The amplifier driven to clip level.
** = Regular music power with 9dB headroom, IEC standard power rating.
HEAT POWER
T
1533 watts / 1975 watts= 78%.
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