Independently researched Practical Guide
Metal Detector Sensitivity and Threshold Explained
Sensitivity controls how strongly the detector responds to weak signals and noise; threshold is an audible reference floor. Raising either without stability can hide targets instead of finding them.
Bottom line
Use the highest stable sensitivity and the faintest useful threshold
Noise cancel and ground balance first, then raise sensitivity until instability appears and back down. In threshold modes, set a barely audible steady tone so small rises, dips and nulls remain noticeable without fatigue.
Field guide
Starting points and hard limits
| Situation | Baseline | Action | Caution |
|---|---|---|---|
| Quiet mild ground | High stable sensitivity | Barely audible threshold if used | Maximum may still be unnecessary |
| EMI-heavy park | Noise cancel then lower sensitivity | Threshold unchanged | Single frequency may help if supported |
| Mineralized goldfield | Lower sensitivity | Stable true threshold | Ground noise can mimic gold |
| Wet salt | Dedicated Beach/PI mode | Reduce sensitivity if needed | Threshold cannot fix wrong architecture |
Method
Use a controlled workflow
Remove external noise
Noise cancel, separate nearby detectors and inspect coil cable.
Control ground response
Ground balance or use the correct salt/ground mode.
Raise to instability
Increase sensitivity, then back down until repeatable audio returns.
Set threshold last
Barely audible in true threshold modes; off where the manual recommends.
Decision analysis
What actually changes the result
Sensitivity is not transmitter power on every detector. It often changes receive gain or processing response; the exact control is platform-specific.
Threshold has two meanings. A true prospecting threshold carries ground/weak-target information, while a reference threshold on some discrimination modes simply supplies an audio baseline.
Instability reduces usable depth. Random chatter masks faint repeatable targets and forces the operator to ignore subtle audio.
FAQ
Seven questions specific to this page
Does maximum sensitivity give maximum depth?
Only in stable conditions; EMI and ground noise at maximum can hide faint targets.
What should threshold sound like?
A barely audible steady reference in modes designed to use a threshold.
Is threshold the same as volume?
No. Volume changes loudness; threshold sets the baseline level or reference tone.
Why does sensitivity need lowering after rain?
Wetter ground can become more conductive and increase ground response.
Should threshold be used in parks?
Only if the detector/mode uses it meaningfully; silent discrimination modes can be easier in modern trash.
Can Audio Gain increase detector depth?
It can make weak audio louder but does not create a target response the detector did not receive.
What is the correct adjustment order?
Noise cancel, ground procedure, sensitivity stability, then threshold/audio preferences.
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Use evidence, not copied numbers
Record the detector, mode, coil and conditions behind every useful result.
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