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If the ground balance adjustment is incorrect, there will be a difference in the sound as
the search coil is either moving toward or away from the ground. It sounds like you are
either pulling the sound out the ground, or pushing the sound into the ground.
•
If the sound is louder as you raise the search coil, increase the ground balance
setting.
•
If the sound is louder as you lower the search coil, reduce the ground balance
setting.
NOTE: Experienced users often prefer to adjust the ground balance to get a weak but
audible response when lowering the search coil, This is called adjusting for positive
response.
Positive and negative response
The purpose of ground balancing is to adjust the metal detector to ignore ground
minerals. If the setting is incorrect, ground minerals will give either a positive or a
negative response, depending on which direction the adjustment is off.
Positive Response
If the GND BL setting is too high a number, the response of minerals will be positive.
This means that when the search coil is lowered to the ground in Pinpoint or ALL METAL
Mode, the sound will get louder as the search coil approaches the ground. The sound
will grow quieter as the search coil is raised. What, if anything, you will hear in DISC
Mode depends on the discrimination setting.
When searching in an ALL METAL Mode, if ground balance is properly set to cancel the
ground, and you sweep over a positive hot rock, the rock will give a “zip” sound similar to
that of a metal object.
Negative Response
If the GND BAL setting is too low a number, the response of minerals will be negative.
When the search coil is lowered to the ground in Pinpoint or ALL METAL Mode, the
machine will be silent. The machine will sound off as the search coil id lifted away from
the ground. What, if anything, you hear in DISC Mode depends on the Discrimination
setting.
When searching in ALL METAL a negative hot rock will produce a “booing” sound after
passing over it, making it difficult to know where it is located. It will not have the sound
and “feel” of a metal object.