Halcro DM38 Owner's Manual page 10

dm38
Output current limiting
In terms of maximum available output current, there are basically 3 amplifier type
options:
a. An amplifier with a reasonable limit placed on the maximum available output
current.
b. An amplifier with no limit placed on the maximum available output current, which
will either blow a fuse or self destruct if excessive current is drawn, for example
through a dead short.
c. An amplifier with a very high limit placed on the maximum available output
current, but designed not to blow a fuse if this very high current is drawn.
If the maximum current drawn from an amplifier with maximum available current
limiting is reached under very loud music conditions (amplifier type a. or c. above),
highly obvious "cracking" overload sounds may be heard. Note that this overload
sound may also occur if a loudspeaker overloads or if any amplifier suffers voltage
overload.
There is an expectation in the audiophile electronic industry that a high end amplifier
should be capable of delivering exactly double the output current for a halving of the
loudspeaker impedance (down to 1 ohm) at the maximum output voltage that the
amplifier can produce.
This requires an amplifier of type b. or c. above. The table below lists an example of an
amplifier rated at 150 Watts output into 8 ohms.
Loudspeaker
load
impedance
8 ohms
4 ohms
2 ohms
1 ohm
If the loudspeaker cable is inadvertently shorted out, these sorts of currents are quite
capable of causing some cables to catch fire. We know of one such instance with an
amplifier rated according to the table!
As we do not wish to set your house on fire we have limited the peak output current
to 15A.
Output Peak output
power voltage
150W 49V
300W 49V
600W 49V
1200W 49V
r.m.s. output Peak output
current
4.33A
8.66A
17.32A
34.64A
TM
current
6.12A
12.25A
24.5A
49.A
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