Peavey CS 1200X User Manual

Page 14

turn

really is maximum compression range), the input sensitivity control should be set at

maximum clockwise setting. This is always the best setting to start with. If, however,

fier is used in a small club, church, or studio application where the full-output capability of
power amplifier is seldom needed, or there is no need for large amounts of

capability,

the full-clockwise setting may not be the wisest choice. Then too, such applications often require
low system noise. In this case, it is possible to reduce the overall system noise at

expense of

headroom capability by increasing the power amplifier

as in the following example:

if, instead of a sensitivity rating of

we adjust the CS

to a rating of

overall system

wilt be improved by

and the system headroom will decrease

COMPRESSION

The CS

is a compact and powerful amplifier that features a new type of dynamic com-

pression. This compression system enables the user to maximize the

of the

combination. We have determined through much research that the compression

circuitry should prevent the power amplifier from running out of headroom (clipping)

and

should

be as simple to operate as possible to avoid undue complication for the

user.

This compression

system is activated by our exclusive DDT compression circuitry, which senses conditions that
might overload

amplifier and activates compression when clipping is imminent. In

words, compression takes place whenever signal conditions exist that prevent

from

faithfully reproducing the input signal. In this case, threshold is clipping itself, and

specific

threshold control is provided. This technique effectively utilizes

precious

watt available

from the power amplifier. Techniques using external compressors/limiters are usually less
effective, severely limit output power levels and require additional controls, and add complexity
to an already complicated system. The DDT system is an automatic, hands-ofl‘approach to
problem of amp clipping.

Because

of the dynamics of music and vocals, it is quite common

activate the DDT compression circuitry almost constantly during a high-level performance, since
this is what it was designed to do: i.e., to maximize the dynamics available from the
within its power-output capabilities regardless of power supply/AC line voltage variations and
load impedance selection. Defeating the DDT compression should be very carefully considered
before one just “flips the switch.” Most loudspeaker systems simply cannot handle

square

wave power of the CS

and defeating the

system opens up the door for

clipping! Often studio engineers

the need to defeat the DDT compressor, for

color the sound in studio listening. The DDT compressor is only activated when clipping is
imminent.

this occurs, it’s simply a passive friend. The only reason the

switch is

there in the first place is to allow check-out technicians to evaluate the power amplifier at clip-
ping. Valuable performance

such as power- supply ripple

and

regulation, can only

be assessed when amplifier is allowed to clip.

THERMAL SYSTEM
The CS 1200X has a unique

system that employs a tunnel-type heat sink design to

provide maximum cooling for the 32 power transistors (16 for each channel). A single 100
fan mounted on the back panel of the unit provides an almost unrestricted airflow through
tunnel to provide the lowest possible operating temperature for the power devices. This approach
is so efficient that even continuous operation into 2 ohms will not cause a thermal shutdown
unless the ambient air temperature is considerably higher than normal (above 40” C).