HOW TO SET GROUND BALANCE

What is Ground Balancing?

The amount of minerals in the soil varies from location to location. Sometimes the composition of minerals change within a small amount of area. Other locations, the mineral composition in the soil will be fairly consistent over a large area. The type of minerals contained in the soil will also vary according to location. For instance, one of the more common minerals present in soil is iron, and some areas of the country have high concentrations present.

Without some method of "ground balancing", the metal detector would be detecting all the minerals present in the soil, therefore not seeing through them, an thus, small or deeper targets would not override the signals produced by the minerals. In extremely mineralized soil, the metal detector would hardly be able to detect a target laying on the surface of the soil.

Ground balancing the detector is simply, the term used to describe the function of adjusting the metal detector to ignore the minerals in the soil so that they are not detected by the metal detector.
Various manufactures utilize different ground balancing options offered on their models such as:

Preset Ground Balancing

Auto Ground Balancing

Manual Ground Balancing

Combination of any preset and manual ground balancing

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Preset Ground Balancing

If the metal detector has the preset ground balancing feature, it has the ground balance adjusted in one set position by the manufacturer, and cannot be adjusted by the user. The manufacturer has adjusted the ground balance of the particular model to an adjustment that they feel will allow the detector to function properly over a wide sampling of soils with varying degrees of mineralization, from highly mineralized to none.

The results of using the factory preset will enable the detector to function throughout the world with its area of varying mineralization. However, since the detector has the ground balance adjustment preset, areas of mineralization which are higher that the adjustment from the factory, will cause the detector to have a "positive" ground balance, and likewise, an area of little or no mineralization will cause the detector to have a "negative" ground balance. To try to better simplify all this, let's assume that the factor made the metal detector with the "preset" ground balance feature. The detector's ground balance adjustment has been set by the factory to ignore "X" amount of minerals. Now suppose you are in a location of the world which has a high concentration of iron in the soil, and the amount of concentration was "X plus" . Since the detector was set to only ignore "X" amount of minerals and your area had more than that present, the metal detector is going to detect the extra amount of minerals present. Likewise, if your location has a concentration of "less than X" minerals, the mineral concentration would be less than the metal detector has been preset for, and would be trying to ignore more signal than it needs to.

The factory preset method of ground balancing will enable the particular metal detector to function pretty good in any location, but performance will vary greatly from location to location. In some locations, the degree of loss of performance will be minimal, in others it will be quite profound.

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Auto Ground Balancing

If a metal detector has an auto ground balancing feature, it tries to compensate for the varying amount of minerals in the soil, by sensing the mineralization and automatically adjusting the ground balance to achieve the best performance. The good side of this feature is, it gives a little more accurate control of the ground balance of the metal detector versus mineralization, as compared to the preset ground balance feature mentioned above. Also, normally, the metal detectors with this feature are a little more expensive than the ones with the preset feature. I have read that if the detector by chance happened to be over a target at the exact time that the "auto" feature was ground balancing the detector, that the target would not be detected. I do not know this to be a fact, only what I have read, but it kind of makes sense to me.

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Manual Ground Balancing

A metal detector which has the manual ground balancing feature is just what it says, the ground balance adjustment has to be done manually by the user. The adjustment will be made by means of a "knob" or "touch pad" control, depending on the particular metal detector and model. We will touch base next on how to manually ground balance the detector.

Imagine you are listening to music on a radio. To increase the volume, you would adjust it by raising the volume control. To decrease the volume you would lower the volume control. What has this got to do with ground balancing a metal detector? Well! The way I figure it, if you cannot operate a radio, you should not purchase a metal detector with a manual ground balance! Not really, manual ground balancing a metal detector is quite easy.

Almost all metal detectors have to be in the "all metal" mode before making a manual ground balance adjustment to the metal detector. Also, most metal detectors have what is called a "threshold sound" when in the "all metal mode."

The threshold sound is simply a background sound or noise that the metal detector produces when in the "all metal mode." The volume of the "threshold sound" should be set to the level that enables the user to faintly hear the consistent sound.

Now to actually go through the process of manually adjusted the ground balance of the detector, the first, and probably the most important factor is to find a spot of the ground you are going to be detecting, which is not close to any large metal object, and free from any metal targets. Once the metal detector has been placed in the "all metal" mode of operation, and the "threshold sound" level has been adjusted to be able to steadily, but faintly, hear the threshold sound, raise the metal detector coil above the ground about one and a half or two feet. From this point on, until the metal detector has successfully been ground balanced, it will be most important to focus on the audio level of the threshold sound. While focusing on the audio level, lower the coil of the detector to the ground. Now, remember the radio volume we talked about earlier? If the audio level of the threshold sound became less or went completely quite, raise the adjustment on the ground balance control, exactly the same way you would increase the volume on a radio. Now, likewise, if the level of the threshold sound gets louder or increases, decrease the adjustment of the ground balance control, just the same way you would decrease the volume level of a radio.

Continue to raise and lower the coil, as described in the fore-mentioned paragraph. This can be in a continual "pumping motion" of raising and lowering the coil and adjusting the ground balance control until the audio level of the threshold sound is steady or unchanging. Remember, if the threshold volume level gets louder when the coil is being lowered to the ground, turn the ground adjustment down. If the threshold volume decreases as the coil is lowered to the ground, increase the ground balance control.

Once you have the metal detector adjusted so the threshold sound level is the same while pumping the detector up and down to the ground, the metal detector is properly ground balanced.

Some metal detector users prefer to have the ground balance adjustment set slightly on the positive side (so the threshold level faintly increases as the coil is lowered to the ground.) Adjusting the ground balance in this slightly positive level will enable a little more depth in areas which have little to no trash targets present.

One thing to remember is that the advantage of a metal detector with the manual ground balance control is that it enables the metal detector to be more versatile in a wide variety of ground mineralization conditions. A proper adjustment of the manual ground balance will enable a little more depth over most equal detectors without the manual adjustment. However, an improper adjustment of the manual ground balance could and in all probability decrease the depth performance of the metal detector greatly.