Sonic Research


True Strobe Display

Easy to read display instantly shows the slightest difference in pitch of the note played from the indicated note. The ring of LEDs is a true stroboscope, driven directly by the analog input signal and a precision internal frequency reference. This gives zero latency and instantly shows the slightest tuning error.

True Bypass / Muted Output

The output of the ST-300 is muted when the tuner is on, and when off the input signal is passed directly to the output. It is completely disconnected from all internal circuitry and the tuner puts zero load on the signal.

Extreme Accuracy

The internal timing generator is calibrated at the factory to maintain a precision of ±.02 cents.

Chromatic Mode

Permits tuning to any of the 12 notes from C0 to C8, in any temperament.

Open Tuning Modes

Tunes to preset or user defined tunings. In this mode the tuner only recognizes notes that are defined for the specified tuning. The tuner comes with a number of pre-defined tunings for stringed instruments. These can be edited by the user.

Power On Restore

The ST-300 remembers the settings for mode, drop tuning and A4 changes. No battery is necessary.

Flat Tuning

Lowers all pitches up to six semitones.

Reference Pitch Change

By default, the tuner uses A4=440Hz as the reference pitch. This can be changed in increments of .1Hz, over the range of 300.0 Hz to 599.9 Hz.


The ST-300 can operate in the equal temperament or any 12 note temperament the user desires. The ST-300 can store a total of 5 different temperaments, in addition to the equal temperament.

Battery or External 9 Volt Operation

The Turbo Tuner ST-300 can operate for 12 hours continuous from a standard alkaline battery. This is enough for about 1,000 tune ups. It also works with any 9 Volt adapter designed for stomp boxes.

Low Battery Indication

When there is about an hour of battery life remaining, a low battery warning is shown on the note display every 2 minutes.



4.4" (11.2cm) x 2.4" (6.1cm) x 1.4" (3.4cm) HxWxD


246 g / 8.7 oz (including battery)


True bypass, muted output. Zero load on signal when tuner is off. Output muted when tuner is on.

Can also be configured to pass the signal through while tuning.

Tuning Range

C0 (16.35 Hz) to C8 (4,186.0 Hz)


+/- .02 Cents (calibrated crystal oscillator)

Reference Pitch

A4 = 300.0 Hz to 599.9 Hz in .1 Hz increments.


Input, Output (1/4") external 9 VDC, parallel 9 VDC

Power Supply

9 Volt Alkaline Battery(included), or external 9 Volt DC adapter (optional).

Power Consumption

48 mA typ. Gives 12 Hour continuous operation with alkaline battery.