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Setup
The amplifier has three sets of connections and one switch: The first connection and switch is
the AC line power system. The amplifier's voltage and current rating are indicated on the
bottom. It will be either 240 volts, 120 volts, or 100 volts, all with a 3AG slow blow type fuse.
The frequency rating of the AC line source is 50 to 60 Hz.
Your amplifier is provided with a standard AC power cord which fits into the line receptacle
located just below the power switch. The amplifier is equipped for operation with an earth
ground provided by the AC outlet. Do not defeat this ground. The chassis of the amplifier is
connected directly to this earth ground, and the audio circuit ground is connected to the
chassis and earth through a power thermistor, which gives a ground safety connection but
helps avoid ground loops. While the amplifier is equipped with an AC inrush suppresser, the
turn-on AC draw will peak (half cycle) at roughly 50 amps on a 120 volt system.
The second connection is at the input, which occurs through a balanced XLR or standard
RCA unbalanced connector. The input impedance of the amplifier is 10 K ohms unbalanced,
and 25 Kohms balanced differential.
The third connection is the amplifier output connection. Connect the 5-way output connectors
to loudspeaker plus and ground, using the cable of your choice. The space is tight around the
output connectors, so use some care to insure that the hot output connection does not short to
the chassis or other connectors. We have provided two sets of output connections in parallel
to facilitate bi-wiring to the loudspeaker.
The amplifier draws 300 watts from the wall at all times, and during idle operation nearly all of
this energy will appear as heat on the heat sinks. Good ventilation is vital to the proper
operation of the amplifier. It has been adjusted for optimal performance at room temperature,
but will work well between 50 and 90 degrees Fahrenheit (10 to 33 Celsius). You should
leave at least six inches clearance on the sides and top. The amplifier should not be placed
in a closed cabinet which does not have forced air ventilation.
This amplifier runs hot. The heat sinks will warm up in about an hour to a temperature which
will not be comfortable to touch for more than a moment or two, which is 120 to 130 degrees
Fahrenheit (50 to 55 degrees Celsius). This is normal, and there is a thermal shut off system
which will shut down the amplifier at internal temperatures in excess of 160 deg. F. and 70
deg. C.
It takes at least an hour of warm up time to get the best performance out of the amplifier. It
will take that long to reach operating temperature and exhibit lowest distortion and noise. This
is not a subjective judgement, but based on actual distortion and noise measurements. You
may find somewhat greater residual noise coming through the loudspeaker when the amplifier
is first turned on, but it will decrease as the amplifier warms up.
The amplifier does not require any maintenance. While the design is conservative, this is a
hard running amplifier, as single ended Class A operation is the least efficient operating
mode. In fifteen years the electrolytic power supply capacitors will get old. Depending on
usage, you will begin to have semiconductor and other failures between 10 and 50 years after
date of manufacture. Later, the sun will cool to a white dwarf, and after that the universe will
experience heat death.
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