Installation And Connection; Bridge Mode - Peavey CS 3000G Operating Manual

INSTALLATION AND CONNECTION

The Peavey CS 3000G 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-l/2" high
and is cooled by automatic two-speed internal fans. All of 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 CS 3000G 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 of the front. However, 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
amplifierwill start up in "Low Speed" fan operation, and will normallystayat low speed operation unless sustained high power
operating levels occur. Then as the amplifier's "Heat Sinks" heat up, the automatic thermal sensing circuitry will cause high
speed operation to occur. Depending on 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 airflow occurs due to blockage of the amplifier inlet/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 on 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 shorted, 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.

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
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 CS 3000G power amplifier can actually drive 70 volt systems directly without using expensive matching
transformers. The real advantage of such an approach is primarily cost.
70 volt distribution systems are very common in applications where rather large numbers of relatively small loudspeakers
are used for background music and paging. Such systems require the use of 70 volt transformers at each loudspeaker.
Another common use for the Bridge mode is in subwoofer applications where very high power levels are required to
adequately reproduce the extreme low frequencies. Such enclosures usually contain 2 or 4 loudspeakers to handle the
power levels involved. For Bridge mode usage, the enclosure impedance must be 4 or 8 ohms; never below 4 ohms! Also
make sure that the enclosure can handle 3000 watts reliably
DDT COMPRESSION
Peavey's patented DDT compression system enables the sound man to maximize the performance of the amplifier/speaker
combination by preventing the power amp from running out of headroom (clipping). This compression system is activated
by a very unique circuit that senses signal conditions that might overload the amplifier and activates compression (reduces
the amp gain) when clipping is imminent. Threshold of compression, then, is clipping itself and no specific threshold control
is used. This technique effectively utilizes every precious watt available for the power amplifier to reproduce the signal while
at the same time minimizes clipping and distortion, and thus significantly reduces the potential of loudspeaker degradation
and damage. The DDT system is an automatic, hands-off approach to the problem of power amplifier clipping. Since the
a more important roll in continuous performance by preventing each channel from clipping and overloading. Continuous
operation at clipping can cause the circuit breaker to trip, but with the DDT activated, this problem is minimized. For this
reason you should always have the DDT compression system enabled.
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