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Boss TU-12 Tuner

Roland have now applied microprocessor technology to the humble tuning aid, the result being a versatile and accurate device ideally suited for stage conditions.

In addition to an 8-LED note display, the TU-12 features a moving coil tuning needle matched with another pair of LEDs indicating sharp or flat signals.

Pitch Selection

The LED display has several functions, the first of these being overall pitch selection. After the unit is switched on, the 'Pitch' button should be held down and the adjacent 'Down' and 'Up' buttons used. These allow selection of A=440, 441, 442, 443, 444 or 445 Hz. Once the Pitch button is released the figure selected becomes the reference standard for the unit.

Chromatic Scale

The power switch has three positions, Off, Guitar, and Chromatic. In the Chromatic scale mode, all the segments of the LED display are in use. These are C, D, E, F, G, A, B, and a Sharp indicator. The LEDs show the nearest note while the meter gives a more accurate reading from A=440 plus or minus 50 cents.

Guitar Scale

With the power switch in the 'Guitar' position, the first four LEDs represent E, A, D, G (for Bass guitars) and the fifth and sixth B and E (for 6-string guitars). In the Guitar mode, the 'Up' and 'Down' buttons are used to step the display along these positions until the string to be tuned is reached.


The meter on the left of the unit covers a range of plus or minus 50 cents, or 10 Hz. An arrow-shaped LED to the left of the meter indicates that the sound being input is slightly flatter than the note indicated on the LED display: another LED to the right indicates that it is slightly sharper. When both LEDs are illuminated the sound is in tune, with further visual confirmation being given by the meter.

Construction and Operation

The tuner is based on a quartz crystal oscillator running at 3.579545 MHz. Internally it's very neatly constructed, all of the components being mounted on one double sided PCB. The three miniature push buttons are raised above this on their own miniature PCB.

The digital processing is done inside a large 72-pin flat pack LSI chip, which uses the crystal as a reference. Many of the other components, such as the meter and LED display, appear to be custom-designed for Roland.

In Use

The tuner is used in conjunction with acoustic instruments via the built-in condenser microphone. Although this should ideally be held near the soundboard or strings of an instrument, it in fact works at quite a distance provided that there is not too much background noise.

For electric or electronic instruments there are a pair of jack sockets for input and output on one end of the tuner. Passing the sound through the tuner causes no distortion or loss of volume, so the unit can be left on or off as desired while playing.

The Tuner is reasonably fast to use, highly accurate and, what is more important, highly visible. It's pocket-sized, operates from a PP3 battery, and is well constructed. The TU12 is not cheap, but if you need a reliable tuner — and most working musicians do — it will give good value for money.

The Boss TU-12 Digital Processing Chromatic Tuner is distributed by Roland UK, (Contact Details), and has a recommended retail price including VAT of £49.00.

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Electronics & Music Maker - Copyright: Music Maker Publications (UK), Future Publishing.


Electronics & Music Maker - May 1983

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