BOSS GM-800

The BOSS GM-800 is a guitar and bass synthesizer in pedal form, released by BOSS in 2023 as the first of its new GM-series synths¹. It is a dedicated synth sound module: instead of processing your normal guitar signal, it takes the divided-pickup signal from a GK-5 (guitar) or GK-5B (bass) pickup through BOSS's newly developed Serial GK interface and drives it with the ZEN-Core sound engine derived from Roland's flagship synthesizers². BOSS describes the result as "natural playability and boundless creative range"³.

Tones, Rhythm parts and Scenes

The GM-800 is a Scene-based platform. Each Scene holds four Tone parts plus a Rhythm part filled with acoustic and electronic percussion sounds³. The onboard library carries over 1200 Tones and 70 Rhythm sounds², and there are 150 user-configurable Scenes, of which 100 come with pro sounds ready to play immediately³.

Effects are handled per part and across the whole Scene:

• Each Tone and Rhythm part has a dedicated MFX processor with over 90 effect types, including distortions, filters, mod effects, delays, and more⁵
• Every Scene adds two more FX for processing the combined sound, plus chorus/delay and reverb effects with independent send levels from each part⁵

Delicious Audio's write-up framed the architecture the same way: "Operating on a Scene-based platform, the GM-800 packs four Tone Parts, a Rhythm section, and an array of synthesis parameters"⁶.

Footswitches, control jacks and MIDI

On the floor, the GM-800 gives you four footswitches, which by default handle Scene selection and two unique control settings such as pedal hold, pitch bend, or Tone control². Two external control jacks are also available, each supporting up to two footswitches or an expression pedal², so a player can expand hands-free control without reaching for a MIDI controller.

For studio and stage integration, the unit carries five-pin MIDI I/O, which BOSS says lets you interface with MIDI equipment from vintage to modern².

Firmware updates and versions

The current system program is Ver.1.50, released in July 2026⁷. It added a TRACKING MODE to GK SETTING that prioritizes responsiveness and reduces latency, improved system stability, and fixed an issue where the unit's operations were sometimes disabled⁷.

On the driver side, GM-800 Driver Ver.1.1.0 for Windows 10/11 was released in May 2024 and is compatible with the GM-800 Ver.1.10 or later; a matching Ver.1.1.0 driver exists for macOS⁸. A Parameter Guide PDF is available from BOSS's owner's manual pages⁹.

From the Roland GR series to the GM-800

The GM-800 did not appear from nowhere. BOSS's own history of Roland and BOSS guitar synthesizers describes 2023 as the year the ZEN-Core-powered GM-800 "bridges" a revolutionary new wave of guitar synthesizer inspiration¹, and the company positions it as the first of the new GM-series synths, "boasts an extraordinary range of natural and abstract sounds"¹⁰. It is also a break from the old 13-pin hardware: the GM-800 is a dedicated guitar synthesizer sound module moving away from conventional 13-pin connectivity, using the Serial GK digital interface over a quarter-inch TRS connection²⁵.

Delicious Audio put the lineage plainly:

That history reaches back to instruments like the Roland GR-300, and forward to BOSS's current synth lineup, including the BOSS SY-1000 and Boss SY-200. BOSS describes the GM-800 as expanding and elevating the concepts behind many historic Roland GR products, merging its latest pitch and string tracking advancements with a cutting-edge sound engine⁶. That engine is the ZEN-Core sound engine, derived from flagship Roland synthesizers². The GM-800 was released in 2023 as the first of the new GM-series synths⁴¹⁰.

For players weighing it against other synth pedals, the GM-800's distinction is that it is a guitar synthesizer with the newly developed Serial GK interface rather than a pitch-tracking stompbox²⁵.

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