BOSS TU-3 Chromatic Tuner for Guitar and Bass, 21-Segment LED Meter

When you need to check tuning between songs or before a set, the BOSS TU-3 puts a dedicated tuner in a stompbox-style format for guitar and bass. Its 21-segment LED meter gives you a clear visual reference, with a high-brightness mode designed to remain visible in bright outdoor conditions.

Choose chromatic mode for a broad range of notes, or guitar/bass mode to tune by string number. That option supports 7-string guitars and 6-string basses, making the TU-3 useful for more than standard string setups.

For players deciding between a tuner attached to an instrument and a pedalboard-style tuner, the TU-3 brings tuning into a compact BOSS stompbox body. Its visual feedback also suits quick checks when you want to focus on the meter rather than rely on a sound-based indication.

Worth noting

The TU-3 is accurate to +/- one cent, and its Accu-Pitch Sign function provides visual confirmation when tuning is complete. Together, these features make it straightforward to see both the tuning movement and when you have reached the target. The meter’s brightness control lets you adjust its display, while the high-brightness mode is especially useful for outdoor playing where glare can make a standard display harder to read.

Chromatic mode handles note-by-note tuning, while the dedicated guitar/bass mode displays notes by string number. For alternate tunings, Guitar Flat mode supports drop tunings up to six semitones below standard pitch. That gives guitarists room to change pitch without giving up the familiar pedal-based tuning workflow.

Who it’s for

This tuner is suited to guitarists and bass players who want a dedicated stage tuner with readable visual feedback. The string-number mode is handy for players who prefer to identify a string directly, including those using 7-string guitars or 6-string basses. Chromatic mode is a practical fit when you need to tune outside a standard guitar or bass setup, and Guitar Flat mode supports players working with lower drop tunings.

A clip-on tuner can make sense when keeping the tuner on the instrument is the priority. The TU-3 takes a different approach: a stompbox format for players who want tuning as part of their stage or pedalboard setup, with a meter designed for quick visual checks.

Tips for day-to-day use

Select the tuning mode that matches your instrument and approach: chromatic for note-based tuning, or guitar/bass mode for string-number guidance. If you play a 7-string guitar or 6-string bass, the supported string modes help you work through the instrument’s strings in sequence. For drop tunings, use Guitar Flat mode and choose the setting that matches the intended pitch, up to six semitones below standard.

On a bright outdoor stage, the high-brightness mode can help keep the LED meter visible. Follow the meter as you tune, then use the Accu-Pitch Sign as a visual check that tuning is complete. This makes the TU-3 well suited to a quick pre-set check or a brief adjustment between songs.

Final verdict

The BOSS TU-3 brings accurate, visual tuning and flexible guitar and bass modes together in a stage-ready stompbox format. It’s a practical choice for players who want string-number guidance, chromatic tuning, support for alternate drop tunings and a bright meter for onstage checks.