Set sensitivity to maximum, set elimination to 0 and threshold to 2-3 go outside and airtest the unit. The elimination feature is worthless and you lose lots of depth. You should hear a break in the threshold at roughly 12 to 13" with the 8" coil when passing a quarter in front of the coil in an even somewhat rapid steady manner. The key is listening to the very low whispers that break the threshold at the mentioned distance. If you hear the break your unit has proper gain. At 9" it should be pretty loud and a noticeable break/sound. I had one and was a great unit, very well built and deep but they will not "discriminate" iron without losing gold.