that particular channel. Operation at power output levels below 100% will naturally be indicated by lower LED readings. The lowest value indicated is 0.4% of full power, which corresponds to
2.0watts RMS output into 4 ohms. Operation below that power level will not be indicated, since the lowest LED is calibrated at 0% or standby. As mentioned, this LED should be illuminated whenever the amplifier is operating with AC mains power applied under zero signal conditions. To the right of each ladder the calibration is “dB below full power.” This is a conven 
ent sea le that indicates the amount of power amp headroom left for any signal condition.
INPUT SENSITIVITY CONTROLS (4)
The CS 1200X features a 31 detented, calibrated sensitivity control for each channel, Each control is labeled to show the actual input sensitivity ratings of the amplifier for various settings in decibel volts necessary to attain the full-output power rating. Thus, maximum input gain (minimum sensitivity rating) is achieved at the full clockwise setting, and this setting yields maximum mixer/system headroom. A setting of less than full clockwise will yield lower system noise at the expense of mixer/system headroom. A more thorough discussion of input sensitivity follows later in this manual.
MAINS POWER SWITCH (5)
The front panel of the CS 1200X contains a conventional on/off rocker switch. When the ampli- fier is plugged into a suitable power source, activating this switch should light both channel “0” array LEDs after the power-up delay sequence is completed (approximately two seconds). You should also be able to hear the output relays close (click). If the amplifier is cool, the fan should start on low-speed operation. If only one channel “0” indicator lights, then the possibility exists of an internal “fault.” If neither channel “0” indicator lights, check the rear panel circuit breakers and the mains power source. It’s always a good idea to check to see that the cooling fan is opera- tional, especially on a new unit. The possibility exists that due to shipping and handling, the fan bearings may be too tight to allow low-speed fan operation. If this is the case, immediately seek professional help. The CS 1200X must have normal fan operation to provide adequate cooling for the unit. Without air flow, the amplifier will “thermal” very quickly under any signal condi- tions.
