Peavey CS 400x - Bridge Mode Operation; DDT Compression System

speed fan operation. If it does however, this may indicate that you have not taken the necessary
steps to provide adequate cooling. Remember, closed up in a cabinet, the CS-400X will have
severe cooling problems, even at low power levels. Again, inadvertent short circuit or sustained
overloaded usage could also cause temporary thermal shutdown. Also, most home wiring and
electrical circuits are only 15 AMPS. Two CS-400X'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 chan¬
nels' power ratings, at a LOAD RATING of twice that of the single channel rating. In this
case, the CS-400X is rated at 300 watts RMS per channel into 2 ohms. The BRIDGE RAT¬
INGS is 600 wans RMS into 4 Ohms (minimum load). Bridge mode operation is accom¬
plished 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 channel B
functions as an input are defeated, and they serve no purpose now.
Another application for BRIDGE mode operation is to drive sound distribution systems in very
large public address applications. In this mode, the CS-400X 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 domestic applications where large numbers of relatively small loudspeakers arc used for
BACKGROUND MUSIC AND PAGING. Such systems require the use of 70 volt TRANS¬
FORMERS at each loudspeaker. Another common use for the BRIDGE mode is in
SUBERWOOFER applications where very high power levels are required to reproduce
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 the enclosure can handle 600 watts reliably.
DDT:
Peavey 's patented DDT compression circuitry enables the sound man to maximize the perfor¬
mance 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 is then clipping itself, and no
specific threshold control is used. This technique effectively utilizes every precious w att
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 CS-400X power amplifier now uses a circuit breaker for over-
current protection, die DDT compression system plays an even more important roll in continu¬
ous performance by preventing each channel from clipping and overload. Continuous opera¬
tion at dipping can cause the circuit breaker to trip, but with the DD f activated, this problem is
minimized. For this reason, you should always have the DD T compression system enabled.