Slide each level to the lowest position on the preamp. This position is where none of the frequencies can be amplified by the internal preamp microphone. Plug the guitar cord into the guitar and into the main sound system amplifier. Turn the power to the main sound system amplifier on.
Set each of the main amplifier levels to 50 percent. This includes the volume, high, middle and low knobs. Push the power level test button on the preamp to test the battery life. If the battery is dead the preamp won't work and will need to be replaced. Look for the red light to come on when the button is pushed. If it comes on the battery is good, but if it remains unlit then the battery is dead.
Increase the volume slowly using the sliding knob on the preamp until the guitar is heard through the main sound amplification system. Strum the guitar a few times to determine volume adjustment levels. The volume can be adjusted throughout the length of the performance depending on the ambient noise of the crowd and other band instruments.
Set the high, middle and low sound frequency sliding knobs to 50 percent. Strum the guitar to listen for the balance between the highs and lows. If the guitar sounds like only the high note strings are sounding then lower the highs and bring up the lows. If the low note strings are overpowering the high note strings, then lower the lows and bring up the highs. Once a balance is struck fine tune the sound with the middle frequency knob. Move it up for a crisper sound and down for a duller sound.