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INSTALLATION AND CONNECTION
The Peavey VX-1.5K commercial series power amplifier is designed for durability in commercial installations
and the quality of performance required in studio and home applications. The unit is a standard rack-mount
configuration. 3 1/2" high and is cooled hv automatic two-speed internal fans. All the input and output
connections are on the back, panel. The front panel contains LED indicators for power and DDT activation,
detented/calibrated sensitivity controls, and a mains power switch.
INDUSTRIAL AND COMMERCIAL INSTALLATIONS
For commercial and other installations, where sustained high power operation is required, the VX-1.5K should
be mounted in a standard 19" rack. It is not necessary to leave rack space between each amplifier in the stack,
since the fan pulls air in from the rear and exhausts the hot air out the front. An adequate ''COOL" air supply
must be provided for the amplifier when rack-mounted. The internal fan must have a source of air that is not
preheated by other equipment. The amplifier will start up in 'LOW SPEED" fan operation, and will normally
stay at low speed operation unless sustained high power operating levels were to occur. Then as the amplifier's
"HEAT SINKS" heat up. the automatic thermal sensing circuitry will cause high speed operation to occur.
Depending upon signal conditions and amp loading, high speed fan operation may continue, or it may cycle
continuously between high and low. This situation is quite normal.
If cooling is inadequate due to preheated air, or a reduction of air flow occurs due to blockage of the amplifier
inlel/outlet ports, or if the amplifier is severely overloaded or short circuited, then the amplifier thermal sensing
system may cause temporary shutdown of that particular channel. This is indicated by the channel power LED on
the front panel ceasing to illuminate. Depending upon available cooling air, operation should be restored in that
channel relatively quickly, and the power LED will be illuminated. In any event corrective action should be
taken to determine the cause of the thermal shutdown. If the amplifier is not severely overloaded or shotted, and
air flow is normal in and out of the unit, then steps should be taken to provide a cooler environment for all the
amplifiers. As a general rule, the cooler electronic equipment is operated, the longer its useful service life.
STUDIO AND HOME INSTALLATION
In most low to medium power applications, the VX-1.5K can be mounted in any configuration. It is desirable
that, if at all possible, the unit be located at the lop of an equipment stack. This will prevent possible overheating
of any sensitive equipment by the hot air rising from the power amplifier. As a general rule, most home and
studio requirements will never cause high speed fan operation. If it does, however, this may indicate that you
have not taken the necessary steps to provide adequate cooling. Remember, dosed up in a cabinet, the VX-1.5K
will have severe cooling problems, even at low power levels. Again, inadvertent short circuit or sustained over¬
loaded usage could also cause temporary thermal shutdown. Also, most home wiring and electrical circuits are
only 15 AMPS. Two VX-1.5K*s could cause a power panel 15 AMP circuit breaker to trip if a severe overload
occurs.
BRIDGE MODE
The bridge mode on stereo amplifiers is often misunderstood as to the actual operation and usage. In basic terms,
when a two channel amplifier is operated in the BRIDGE mode, it is converted into a single channel unit with a
POWER RATING equal to the sum of both channel's power ratings, and at a LOAD RATING of twice that of
the single channel rating. In this case the VX- 1.5K is rated at 750 W RMS per channel into 2 ohms. Thus the
BRIDGE RATING is 1500 W RMS into 4 ohms (minimum load). Bridge mode operation is accomplished by
placing the mode switch in the "BRIDGE" position, connecting the load between the RED binding posts of each
channel, and using channel A as the input channel. All the channel B functions as an input are defeated and they
serve no purpose in bridge mode.
A popular application for BRIDGE mode operation is to drive sound distribution systems in large public address
applications. In this mode, the VX- 1.5K power amplifier can actually drive 70 volt systems directly without
using expensive matching transformers. The real advantage of such an approach is primarily cost.
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