Output Transistor Protection - Halcro Eclipse mono Owner's Manual

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Table of Contents

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

parameters in table 3!

As we do not wish to set your house on fire we have

limited the peak output current to 15 A.

One also has to question the belief that an amplifier

should be capable of such unreasonably high output

currents. Consider the following facts:

o Most loudspeakers have impedances of 4

ohms (not 1 or 2 ohms)

o All valve amplifiers are output current limited,

and yet the industry does not consider this a

problem, which is inconsistent with the belief

that maximum available current limiting is a

problem

o All well designed loudspeakers have

impedances that do not deviate excessively

from their nominal impedances and hence no

excessively high currents are required anyway

o If indeed a 4 or 8 ohm loudspeaker does have

an impedance of 1 ohm at a particular

frequency, one must wonder where the heat

generated is dissipated if this load is

predominantly resistive or why the coupling is

so poor if this load is predominantly reactive

Hence we believe that these excessively high output

currents are:

o Not required for well designed loudspeakers

o Highly dangerous

Many people have listened to maximum available

current limited amplifiers played through different

loudspeakers without encountering any current

limiting problems, that is, obvious "cracking" sounds

at very loud listening levels, except for loudspeaker

or voltage overloads which are independent of

current limiting.