Boss TU3 Tuner

The Boss TU-3 is a chromatic pedal tuner in the familiar Boss compact stompbox body, and it is the pedal many players reach for when they need to tune mid-show. It reads any note you feed it, displays your pitch on a bright 21-segment LED meter with a High-Brightness mode that Boss says cuts through harsh outdoor glare, and it does its job with plus or minus one-cent accuracy¹². It replaced the Boss TU-2 in the lineup and has been a stage standard ever since¹³.

What sets the TU-3 apart from a simple tuner in a box is that it also works as a buffer. Boss says its circuitry includes a high-quality signal buffer that converts the pedal's output to low impedance, eliminating treble loss and tone dulling with long cables and true-bypass chains². That is one reason it sits at the front of so many pedalboards.

What it does and how you control it

The TU-3 offers a choice between Chromatic mode, which reads any pitch, and a Guitar/Bass mode tailored to those instruments¹. The display is a 21-segment LED meter, and the High-Brightness mode is there for daylight and outdoor stages where dim tuner displays wash out¹. MusicRadar's review quotes the accuracy at +/-1 cent over a 23-segment LED display⁶.

Two settings matter to gigging players:

• Drop tuning: up to six semitones below standard pitch, plus bass tuning up to three flats⁶.
• Reference pitch: adjustable over a range of 436 to 445Hz, so you can tune to something other than A440⁷.

EarthQuaker Devices' pedalboard guide adds a practical warning about the flat settings: "Just make sure you don't accidentally set it to 1/2 step down when your band plays in standard tuning; they will never [forgive you]"⁸.

The buffer, and why the TU-3 is not true bypass

The TU-3 uses a buffered output rather than true-bypass switching, a point MusicRadar notes "may be an issue for the tone-obsessed"⁶. Guitar World's beginner pedal guide lists buffered bypass as the pedal's one drawback⁹. Boss's own position is that the buffer is a feature, not a compromise: the TU-3's buffer converts the output to low impedance, which keeps the signal clear and strong down long cable runs and through chains of true-bypass pedals²¹⁰.

Caroline Guitar Company made a similar point about the TU-3's predecessor years earlier, noting that the TU-2 "does triple duty as a tuner, a mute, and a buffer"¹¹¹. Boss describes the TU-3 and the TU-2 before it as the stage tuners of choice for two decades running²¹.

Powering other pedals

The TU-3 runs on 9V DC, center negative, drawing 20mA¹. It can also act as a small power hub: using the recommended Boss supply and a PCS-20A daisy chain, the TU-3 will supply a total of 200mA to up to seven other Boss compact pedals⁶. For a small board built around Boss compacts, that is one less power supply to buy.

TU-3, TU-3W and TU-3S

The current Boss lineup includes the standard TU-3 plus two variations²:

The TU-3W, announced in 2016, provides tuning functions equivalent to the TU-3 at its core, with redesigned circuitry and what Guitar World called "the most transparent audio pass-through possible"¹³¹². Boss's Waza Craft article describes it as bringing "Waza Craft mojo to the world's leading stompbox tuner"¹⁴. The TU-3S, announced the same year, offers the same industry-standard performance in a scaled-down size, always on and ready to go, with the pedal switch eliminated¹²¹³.

Where it came from

What reviewers and players say

Guitar World's beginner pedal guide summed the TU-3 up as "Super accurate, built like a tank, easy to use," with buffered bypass listed as the minus⁹. Guitar.com's review of a competing tuner called the Boss TU-3 "pretty much the industry standard, and good enough for countless professional pedalboards"⁴. Boss describes its compact pedals as renowned for being nearly indestructible, delivering years of trouble-free operation under tough touring conditions².

The TU-3 shows up on professional boards across genres. Premier Guitar's rig rundowns have spotted a Boss TU-3 Chromatic Tuner keeping Rise Against's guitars in check¹⁵ and a Boss TU-3 tuner on Umphrey's McGee's boards¹⁶. In a Boss interview, Winyah's Thomas Rowland said of his TU-3: "I've had it forever, my mom bought it for me when I was like 14. It's been on my board for almost ten years now"¹⁷.

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