Crest Audio Stereo Amplifier - Manual (Page 5)

Crest Audio Pro Series Power Amplifiers Page 3
Cooling Requirements
The Professional Series amplifiers use a forced-air cooling system to maintain a low, even operating temperature. Air is drawn into the
amplifier by fan(s) on the rear panel, courses through the cooling fins of the back-to-back (tunnel-configured) channel heat sinks, and
then exhausts through the front panel slots.
If either heat sink gets too hot, its sensing circuit will open the output relay, disconnecting the load from that particular channel. If the
power transformer overheats, another sensing circuit opens the output relays on all channels until it cools to a safe temperature.
It is important to have an adequate air supply at the back of the amplifier and enough space around the front of the amplifier to allow
the cooling air to escape. If the amp is rack mounted, do not use doors or covers on the front of the rack; the exhaust air must flow
without resistance. If you are using racks with closed backs, use fans on the rear rack panel to pressurize the rack and ensure an ample
air supply; also make sure that there is one (1) standard rack space opening for every three mounted power amplifiers.
The Professional Series amplifiers are supplied with cooling fan air filters. The filters snap in place over the fan housing. Any filter will
decrease airflow somewhat, so use the filter only when the amplifier is used in a dusty environment without a filtered air supply. The
filter element must be cleaned or replaced periodically (see the section on Amplifier Maintenance for filter service procedures).
Operating Precautions
Make sure the mains voltage is correct and is the same as that printed on the rear of the amplifier. Damage caused by connecting the
amplifier to improper AC voltage is not covered by any warranty. See the Connecting Power section for more information on voltage
requirements.
Note: Always turn off and disconnect the amplifier from mains voltage before making audio connections. Also, as an extra precaution,
have the attenuators turned down during power-up.
Although the Professional Series amplifiers have AutoRamp circuitry, which raises the signal level gradually after the output relay clos-
es, it is always a good idea to have the gain controls turned down during power-up to prevent speaker damage if there is a high signal
level at the inputs. Whether you buy or make them, use good-quality connections, input cables, and speaker cables, along with good
soldering technique, to ensure trouble-free operation. Most intermittent problems are caused by faulty cables.
Consult the Wire Gauge Charts to determine proper gauges for different load impedances and cable lengths. Remember that cable resis-
tance robs amplifier power in two ways: power lost directly to resistance (I
2 R loss), and by lowering the total load impedance. Also
make sure the mode switch is correctly set for the desired application. See Sections on Stereo, Parallel, and Bridged Mono Operation
for more information.
The Crest Audio Model 7301 Power Amplifier
The Model 7301 is specifically designed for use in bi-amplified systems; because of its dissimilar channel design, the specifications
are reported in a separate fashion. The 7301 power specifications were obtained by driving the low frequency channel with a 100 Hz
signal and the high frequency channel with a 1 kHz signal.
The Crest Audio Model 10004 Power Amplifier
The Model 10004 power amplifier is unique in that it is a high-power, four-channel amplifier. Offering the advantages of Crest Audio’s
Power Density engineering design philosophy, this amplifier provides 1400 watts at 2
Ω
from each of the four channels. All four chan-
nels have independent LED indicators, attenuation, and input /output connections. Power switching and NexSys interfaces are config-
ured in pairs of two. Because a channel may have to drive more than one speaker line, each channel has two pairs of output binding
posts. The red binding posts are hot (+), while the black binding posts are at signal ground (-).