5 Advanced Features and Options
5.3 Options
5.3.1
Available in limited quantity through Crown’s Parts Department, the
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5.3.2 Input Sensitivity Switch
The Input Sensitivity Switch is located inside the back of the amplifier (Figure 5.1). It is set at the factory to 0.775 volt for rated output into 8 ohms. It can also be switched to a sensitivity of 1.4 volts, or a fixed voltage gain of 26 dB (4.8 volts for rated output).
How to change the input sensitivity:
1.Turn off the amplifier and disconnect its power cord from the AC mains power receptacle.
2.Remove the PIP module (two screws).
3.Locate the sensitivity switch access hole inside the chassis opening as shown in Figure 5.1. It is located just above the phone jack inputs.
4.Set the switch to the desired position noted on the access hole label. The position toward the front panel sets the sensitivity to 1.4 volts for rated output, the middle position provides a voltage gain of 26 dB, and the position toward the back panel sets the sensitivity to 0.775 volt for rated output.
5.Replace the PIP module and restore the power.
5.3.3 Input Ground Lift Switch
The Input Ground Lift switch is located on the rear panel (Figure 5.1) and can provide isolation between the input signal ground and the AC ground. It affects only the phone jack inputs and has no effect on the input connec- tors on the PIP module. Sliding the switch to the left iso- lates or “lifts” the grounds by placing an impedance between the sleeve of each phone jack and the circuit ground.
When a PIP module is plugged into the amplifier, only the noninverted and inverted signal lines are connected in parallel with the corresponding lines of the input phone jacks. The signal grounds are not paralleled. For exam- ple, XLR pins 2 and 3 are connected in parallel with the tip and ring of the corresponding phone jack. However pin 1 of the XLR is not connected in parallel with the sleeve of the phone jack.
Figure 5.1 Input Sensitivity and Ground Lift Switches
1Note that the
Operation Manual | page 15 |