Competing vibrations
Open strings can resonate sympathetically even when you pluck only one string. A tuner may alternate between the fundamental, an overtone, and another ringing string. Rest both hands lightly on unused strings before each note.
Signal problems
Microphone tuners struggle with fans, voices, television audio, and reflections in a noisy room. Electric guitars should use a clean tone, sufficient volume, and preferably the neck pickup. Avoid distortion, chorus, delay, and reverb while tuning.
When the string is the problem
A very old, kinked, dirty, or loosely installed string may not produce one stable pitch. If the note audibly wavers after correct winding and seating, replace the string and check the nut and bridge contact points.
Step-by-step check
- Stop all six strings with your hands.
- Choose one string and release only that string.
- Pluck once with moderate force.
- Wait briefly for the pitch to settle.
- Move closer to the microphone or improve the direct signal if the display still jumps.
Reliable tuning habits
Work with one string at a time, use a moderate and repeatable picking attack, and let the initial pitch settle briefly. Make the final adjustment by approaching the target from below so slack is taken out of the tuning post and nut. After all six strings are close, repeat the entire pass because every tension change can slightly affect the other strings.