Level Control (gain control adjustment)
The level control is not a volume knob, it is used to match the relative output level (voltage) of your source unit to the input circuit of your amplifier. The level control determines how far you have to increase the volume on your source unit for the amplifier to reach full power.
Level control can also be known as;
- gain control
- input sensitivity
If you have your level control set too low, your amplifier will not be able to reach full power and this could allow the source unit to clip, which in turn will result in a distorted signal being delivered to your speakers. This is especially relevant with low voltage sources (lower than 2.5 volts - typically OEM units). With higher voltage sources (2.5 volts or higher) if the level control is set too high, the amplifier will be able to reach full power at a lower volume control setting from the source unit. This will allow the amplifier to be driven into clipping*.
The level control settings should generally be set lower, meaning a higher setting on the volume control of the source, to minimise amplifier clipping.
Guide to Setting Level Control
If you do not have the technical equipment (oscilloscope) the following steps will assist in setting your amplifier level:
1) Once you have installed the audio system, turn both the source unit and amplifier power off
2) Adjust the amplifier level control to the minimum setting
3) Turn the power on for both the source unit and the amplifier and adjust the volume control of your source unit to approx 3/4 of the maximum volume level.
4) Slowly increase the level control until it reaches the maximum level you are comfortable with or untill it starts to clip. If it starts to clip, reduce the level control until you have a clean undistorted signal.
*Clipping or distortion is the audible sign of an unclean signal - in basic terms, you will hear a distorted sound