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MXR Enters the Tuner Market with the New Turbo Tuner M400 Built around Sonic Research’s precision strobe technology, MXR’s first-ever tuner pedal promises extreme accuracy, extensive tuning customisation, and flexible signal routing. MXR is stepping into new territory with the launch of the Turbo Tuner M400, the brand’s first-ever tuner pedal. Developed in collaboration with Sonic Research, the new stompbox brings the company’s renowned Turbo Tuner technology into a compact MXR enclosure, combining professional-grade tuning accuracy with a feature set designed for both guitarists and bass players. At the heart of the M400 is a true strobe tuning system rated at ±0.02 cents of accuracy. Alongside its high-precision tuning capabilities, the pedal offers programmable presets, alternate temperaments, adjustable display brightness, and a choice between true bypass and buffered operation. Precision Tuning with a True Strobe Display The M400 uses a genuine strobe display rather than a simulated needle or conventional moving indicator. Its LED ring responds to pitch variations, rotating in one direction when a note is sharp and the opposite direction when it is flat. As the instrument approaches the correct pitch, the movement slows until the display settles. MXR rates the tuner’s accuracy at ±0.02 cents across a range from C0 to C8, making it an exceptionally precise option for players who demand fine adjustments when tuning their instruments. For bass players, that precision is particularly relevant when setting up an instrument, matching tuning across multiple basses, or working with extended-range instruments where consistent intonation and tuning stability are essential. The display also features four brightness settings, allowing players to adjust visibility for different environments, from dim rehearsal rooms to brightly lit stages and outdoor performances. Designed for Everyone The Turbo Tuner M400 includes chromatic mode, which tracks all twelve notes, alongside dedicated guitar and bass modes that identify strings by number rather than note name. It also provides five programmable instrument presets, including three additional slots initially configured for standard guitar, Drop D, and six-string bass tunings. These presets can be customised for instruments with up to 12 strings, with tuning offsets adjustable in 0.1-cent increments across a range of ±50 cents. The pedal also supports alternate temperaments, giving players the ability to move beyond standard equal temperament and customise tuning for particular musical requirements. For bass players experimenting with alternate tunings, extended-range instruments, or non-standard musical systems, this level of flexibility makes the M400 more than a conventional plug-in-and-tune pedal. True Bypass or Buffered Operation The M400 offers a choice between true bypass and buffered operation, allowing players to configure it according to their signal chain. In true-bypass mode, the pedal mutes the output while tuning and removes itself from the signal path when switched off. Buffered operation provides three selectable configurations: muting the output while tuning, keeping the instrument signal active while the tuner runs, or leaving the tuner active and using the footswitch as a mute. The buffer option is particularly useful for players running long cable lengths or larger pedalboards, where maintaining high-frequency response can become a consideration. Compact Design and Practical Connectivity The Turbo Tuner M400 follows the familiar MXR stompbox format, with a die-cast aluminium enclosure designed to integrate easily into an existing pedalboard. Its connectivity includes standard instrument input and output connections, a 9V DC power input, and a dedicated output for passing power to another pedal. A USB-C connection supports firmware updates and access to the tuner’s editing software. The pedal can also run from a 9V battery, providing an alternative for players who prefer not to rely exclusively on an external power supply. Pricing and Availability The MXR Turbo Tuner M400 has a US suggested retail price of $149.99 and is beginning its rollout through retailers. European pricing and availability may vary by market. By combining Sonic Research’s established strobe tuning technology with MXR’s familiar pedal format, the M400 represents a significant addition to the brand’s catalogue. For bass players looking for a compact tuner with extremely fine accuracy, extensive preset customisation, and flexible signal-routing options, MXR’s first entry into the tuner market is certainly one to watch.