| The value jumps by an octave | The detector is alternating between the head's fundamental and a stronger overtone. | Tap more lightly, move closer to the tested lug, and use the target range as context. Repeat several taps before adjusting. |
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| The value changes around the head | Lug tension is uneven, or the opposite head is still contributing. | Mute the other head firmly and compare opposite lugs in a star pattern. |
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| A low drum shows no stable pitch | The microphone may roll off at low frequencies, or the room is dominating the reading. | Measure near-lug targets first, move the microphone closer, and verify the center result by ear. |
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| The center hit does not match the lug target | That is expected: they are different acoustic measurements. | Compare center hit with the assembled-fundamental target and lug taps with the selected head target. |
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