Effects in the MD-500 include many new Prime types developed with cutting-edge BOSS tech, plus authentic sonic recreations of vintage classics like the CE-1 Chorus Ensemble, Roland Dimension D, ‘70s script phaser, ‘80s tri-chorus, and numerous others. With the ability to use two patches at once with A/B Simul mode, the MD-500 can likely cover all your mod needs with one convenient pedal. And by inserting drive pedals in the MD-500’s flexible external loop, it’s easy to place mod effects before, after, or around the loop as needed for the very best sound.

Studio-level sound with first-in-class 32-bit AD/DA, 32-bit floating point processing, and 96 kHz sampling rate

12 modes and 28 modulation types, all with deep editing parameters

Classic mod effects and BOSS originals, newly enhanced with cutting-edge technology

A/B Simul mode for using two patches at once, with your choice of series/parallel connection and mixed or split A/B output

Insert Loop function allows you to use mod effects before, after, or around drive pedals

Graphic LCD and intensive real-time control options

297 onboard patch memories and hands-on controls

Selectable buffered-bypass or true-bypass operation

MIDI I/O for interfacing with MIDI control devices

USB-MIDI for connecting to the MD-500 Editor/Librarian or a DAW

Runs on four AA-size batteries or PSA-series AC adapter

Twelve Modes and 28 Mod Effect Types

The MD-500 includes 12 modes with 28 different mod effect algorithms, and every one of them has been newly developed specifically for this pedal. All the go-to standards are here: chorus, vibrato, flanger, phaser, tremolo, rotary, classic vibe, and ring mod. Auto wah and touch wah effects are on hand too, plus BOSS originals like Slicer and Overtone. Slicer fans will welcome the ability to program custom patterns, an additional feature to the original SL-20 Slicer pedal. And with the MD-500’s spot-on recreation of Roland’s Dimension D from the 1980s, you can add amazing width and depth with one of the most revered studio rack effects of all time.

Prime Tone

For the MD-500, standard effects like chorus, flanger, phaser, and others have been refreshed with BOSS’s advanced new Prime algorithms. Using ultra-fast, high-powered DSP and the latest technology, BOSS engineers have reimagined these essential effects for enhanced expression, extended range, and maximum transparency. With an array of adjustable parameters per type, you have a massive range of sound-shaping potential at your fingers. Some effects even have all-new parameters never seen in BOSS effects before, such as the “Bell” and “Sweetness” settings included in the Prime Chorus algorithm.

Extraordinary Sound

The MD-500 features 32-bit/96 kHz AD/DA, exceeding all industry standards for pedal-based effects. All internal processing is 32-bit floating point and runs at a 96 kHz sampling rate as well, delivering pristine sonic quality that goes beyond the highest-level digital processors used in top pro studios. And with selectable true-bypass or buffered-bypass operation, you can choose the best setting to suit the needs of any pedalboard setup.

Advanced Interface, Intuitive Operation

The MD-500 is equipped with a large LCD that clearly shows the patch name and other vital performance information. It also makes it easy to view and adjust the unit’s deep editing parameters and advanced control features. With the grab-and-go panel knobs, you have top-level access to essential adjustments like depth and effect level, plus two parameter controls that change dynamically with the selected effect type. And via USB, you can connect with the free MD-500 Editor/Librarian on your computer for remote editing, patch backup, and more.

A/B Simul Mode and Insert Loop Function

A/B Simul mode further extends the MD-500’s versatility by letting you run two patches at once. A selectable series or parallel connection enables all sorts of tone-shaping possibilities, and you can even send each effect to its own separate output if you like. The MD-500 also features an external loop that lets you insert gain and drive pedals and set the ideal effect order on a per-patch basis. For example, you can place a phaser or classic vibe before a drive pedal in one patch, and a chorus or flanger after the drive in the next. And when you’re in A/B Simul mode, it’s even possible to position the loop between two different mod effects.

Intensive Real-Time Control

With its freely assignable switches and extensive real-time control support, the MD-500 delivers unmatched expression and performance flexibility. By default, the A, B, and TAP/CTL switches offer control for patch/bank selection and bypass, plus tap tempo or real-time adjustment of one or more parameters. If you like, the switches can be customized to access three different mod patches, A/B Simul mode, and other functions. Via the rear-panel CTL 1,2/EXP jack, you can plug in up to two footswitches for further control, or an expression pedal to adjust wah, effect rate, and other parameters. MIDI I/O is also included, enabling further creative possibilities with advanced setups.

MD-500 Modes and Algorithms

Chorus—Four types: Prime, CE-1 Chorus, CE-1 Vibrato, and TRI-CHO.

Flanger—Two types: Prime G (for guitar) and Prime B (for bass).

Phaser— Three types: Prime G (for guitar), Prime B (for bass), and Script.

Classic Vibe—Two types: Chorus (mixed output) and Vibrato (effect-only output).

Vibrato—Two types: Prime and Scanner (tonewheel organ-style vibrato).

Tremolo—Four types: Prime T and Prime P, plus Twin and Deluxe amp-style tremolo.

Dimension—Models the legendary Roland SDD-320 Dimension D rack unit; includes the original four sound modes and an all-new fifth mode, plus a user setting for saving any combination of modes.

Ring Mod—Classic ring modulation effects, plus Intelligent mode for enhanced clarity when playing scales.

Rotary—Vintage rotating speaker effect with slow and fast speeds.

Filter—Auto wah and touch wah (with independent types optimized for guitar and bass), plus pattern filter type.

Slicer—Original BOSS effect derived from the popular SL-20 Slicer, with programmable options not available in the SL-20 pedal.

Overtone—Original BOSS effect based on the MO-2 Multi Overtone pedal; uses MDP tech to alter the input signal’s pitch and harmonic characteristics, allowing you to create unique new sound textures.