I turn it on and set Sens. at 10, then I put the Bandido in Auto-Tune all metal and adjust for a just audible Threshold hum. then lower coil tfrom 8 inches to 1 inch above ground on a clean metal free piece ground. Use a brisk up and down motion and note what the threshold does. If the Threshold gets louder as coil approaches ground turn GB knob counterclockwise a little at a time under there is no noticeable rise of Threshold hum...... if it get quiet as coil nears ground turn clockwise a little at a time until you get a neutral setting,,,,,,easy as that.