The balancing act
I feel that ground balancing is very important and yet one of the least understood aspects of metal detecting, so I thought I'd do my best to make it a bit simpler. I like comparing ground balancing a detector to a more familiar process such as tuning your car radio.
Ground balancing(GB), also known as "tuning" your detector is very important for getting those really deep faint signals. Much like tuning in a distant weak radio station. The trick is to get a good strong signal through the background noise. Background noise is that static you hear on your radio in between stations. A metal detector has the same kind of background noise to deal with. That background noise can be interference from nearby electronics, sun spots, ground minerals and trash.
As important as proper tuning of your car radio to hear those faint stations, so is proper GB/tuning your detector to hear those faint targets.
Not all detectors have the same GB abilities. You have Auto GB(more on this later), Manual GB and Auto Tracking. Some detector manufactures advertise having Auto GB when this is a play on meaning, and misleading. One would think that Auto GB means it automatically adjusts the GB for best performance, when in fact it is a factory set GB, and is not always set to give you optimum performance in some ground conditions. I like the analogy that Auto GB is like welding your gas pedal half way down and calling it cruse control.
Manual GB is the preferred method for optimum performance. It allows you to fine tune your detectors GB so that hearing and identifying those very faint signals is easier. The process is to hold the coil about waist height and in all-metal mode listen for a change in the threshold as the coil is lowered to the ground. Of course this has got to be done over ground that is free from any targets. If when the coil is lowered to the ground and the threshold changes(lower of higher) then your GB is not set for optimum performance. If your detector has no GB adjustments, then you've got nothing you can do. For shallower targets(closer radio stations) this isn't much of an issue, but you probably won't hear those deep faint(far way stations) targets. When a detector is properly GB's there will be no changes in the threshold when lowered from the waist to the ground. Also called a neutral GB.
TIP: Experienced detectorist often prefer a slight positive GB. This means the detector is set so that there is a slight rise in the threshold as the coil is lowered to the ground. This setting can give you a slight more gain on those very deep faint signals.
Auto Tracking is a feature, offered by some of the high end detectors, that can track changes in the ground minerals, and adjust automatically on the fly to maintain optimum performance. Just as the background noise(ground minerals) can change on your car radio as you move, so can the background noise on your detector. Auto Tracking monitors the ground changes and adjusts as needed. Some detectors such as the White's DFX even gives you a way to adjust the ground tracking. Very aggressive ground tracking can give the very best in performance in certain conditions, but having too aggressive tracking can cause false signals.
