M400 Turbo Tuner

The MXR Sonic Research Turbo Tuner M400 is a high-precision chromatic strobe tuner developed in collaboration with Sonic Research, featuring the tuning capabilities of the ST-300 with additional selectable buffering. Its true strobe display provides pitch detection across eight octaves, from C0 to C8, with guaranteed accuracy of ±0.02 cents. The pedal supports five customizable open-tuning modes, five alternate temperaments, drop tuning up to six semitones, and adjustable A4 reference pitch from 300.0 to 599.9 Hz in 0.1 Hz increments. A high-brightness display offers adjustable dimming for different lighting conditions. Three output modes provide true-bypass and buffered operation. Additional features include settings memory, a low-battery indicator and operation from a 9V battery or external 9V DC power supply.