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GENERAL INFORMATION
High quality amplifiers adjusted to operate at low inherent distortion levels must function in the Class A
region. The efficiency of a Class A amplifier falls somewhere between 30 and 35%. This means that an amplifier
which is capable of producing 120 watts of audio power must consume a minimum of 350 watts of AC power.
With ordinary program material, only a small portion of this 350 watts of power is converted into audio en ergy.
Everything else is converted into heat energy.
It is therefore evident that an amplifier designed to produce 120 watts of audio power must be constructed
to dissipate a great amount of heat while operating on an extended basis without deterioration of its perform -
ance. The Citation Il basic amplifier has been designed in just that way. The selection of components and their
positioning in the chassis has been given careful consideration and will provide many years of trouble free opera -
tion.
The Citation II power transformer is potted with a chemical compound called “PERMAFIL” which is
specifically selected because of its high heat conductivity. “PERMAFIL” carries the heat away from the core and
the winding to the outer can where it is rapidly dissipated. As a result the transformer can, after extended use,
will feel hot to the touch even though the inner core and windings are operating at a conservative temperature.
A slight red glow within the KT88/6550 output tube is normal and there should be no cause for concern.
This will not affect the life or performance of the tube. A bright cherry red plate indicates the tube is running
away and the bias and output circuit should be checked immediately.
VOLTAGE AND RESISTANCE CHECKS
Refer to the complete voltage and resistance chart for correct readings.
TUBE REPLACEMENT
The use of balanced output tubes is preferred although not mandatory. There is a statistical rate of
probability that matched tubes will age at a more equal rate than unmatched tubes requiring less frequent ad -
justment. If it is necessary to replace a KT88/6550 output tube, it is advisable to replace both tubes of the
channel. Matched KT88/6550’s are available at most stores or through Harman-Kardon.
