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turn really is maximum compression range), the input sensitivity control should be set at
Ihe
maximum clockwise setting. This is always the best setting to start with. If, however,
the
ampti-
fier is used in a small club, church, or studio application where the full-output capability of
the
power amplifier is seldom needed, or there is no need for large amounts of
headroom
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
the
expense of
headroom capability by increasing the power amplifier
sensitivity
as in the following example:
if, instead of a sensitivity rating of
+3
dB
V,
we adjust the CS
1200X
to a rating of
+
t2dB
V,
overall system
noise
wilt be improved by
9
dB,
and the system headroom will decrease
9
dB.
DDT’lM
COMPRESSION
The CS
1200X
is a compact and powerful amplifier that features a new type of dynamic com-
pression. This compression system enables the user to maximize the performance of the
ampti-
fier/speaker 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
the
amplifier and activates compression when clipping is imminent. In
other
words, compression takes place whenever signal conditions exist that prevent
the
amptil‘iers
from
faithfully reproducing the input signal. In this case, threshold is clipping itself, and
no
specific
threshold control is provided. This technique effectively utilizes every 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
Ihe
problem of amp clipping. Because of the dynamics of music and vocals, it is quite common
lo
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 amplifier
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
the
square
wave power of the CS
1200X,
and defeating the
D9T
system opens up the door for
sevcrc
clipping! Often studio engineers
feel
the need to defeat the DDT compressor, for fear it
might
color the sound in studio listening. The DDT compressor is only activated when clipping is
imminent.
LJntit
this occurs, it’s simply a passive friend. The only reason the dcfcat switch is
there in the first place is to allow check-out technicians to evaluate the power amplifier at clip-
ping. Valuable performance
illformation,
such as power- supply ripple and regulation, can only
be assessed when
an
amplifier is allowed to clip.
THERMAL SYSTEM
The CS 1200X has a unique
thermal
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
CF;M
fan mounted on the back panel of the unit provides an almost unrestricted airflow through
Ihe
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).
Under
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