Boss RT-2 Rotary Ensemble

The Boss RT-2 Rotary Ensemble is a rotary speaker effect in a Boss compact pedal, released in 2025. It recreates the sound and behavior of a spinning speaker cabinet, the effect most players know from organ records and psychedelic guitar, without the weight, cost or maintenance of the real thing. Boss says it drew on "cutting-edge DSP and an intensive study of the revered Leslie 122 cabinet" to build its most faithful rotary emulation yet¹.

A real Leslie cabinet uses a rotating treble horn and a rotating bass rotor to throw sound around a room, producing the characteristic doppler swirl. The RT-2 condenses that into a standard compact Boss enclosure, with a virtual rotor display of lights showing the treble and bass rotor speeds, stereo outputs, and a Drive knob that adds the tube-amp saturation a real Leslie's amplifier contributes².

A Leslie 122 in a compact pedal

Boss describes the RT-2 as delivering "authentic rotary speaker sounds and behaviors condensed into a space-saving BOSS compact pedal"⁶. The starting point is Mode I, which Boss calls a faithful reproduction of the most famous vintage rotary speaker design, realized with its latest modeling technology, and intended for guitar, bass, organs, electric pianos, synthesizers and more².

For players who have considered an actual Leslie, Pedal of the Day put the practical case plainly: the RT-2 is "about $2000 cheaper and weighs roughly 5% of a real Leslie cabinet, so transportation and maintenance are a cinch"⁷.

The pedal offers two stereo output modes: standard stereo (the default) or individual wet and dry outputs, which lets you keep a clean signal path alongside the effect².

The controls: Mode, Drive, Rise/Fall and Balance

The RT-2 keeps the control set small, in keeping with the compact format. Three modes cover the tonal ground, and a handful of knobs and switches shape the response²⁸.

The three modes each take the rotary sound in a different direction²:

• Mode I: A faithful reproduction of the most famous vintage rotary speaker design. Guitar World's Jonathan Horsley called it "straight-up vintage, which gives us strong Leslie vibes"³.
• Mode II: The vintage sound with a wider tonal range, giving increased spatial performance when paired with overdrive and distortion pedals. Horsley noted it "opens up the tonal range"³.
• Mode III: Enhanced definition with intense modulation and drive settings, adding power and presence to arpeggio playing and solos².

The Rise/Fall control matters because the transition between slow and fast rotor speeds is a big part of how a rotary speaker feels to play: a real Leslie's rotors take time to spin up and down, and shaping that ramp changes the character of the swell. Delicious Audio notes users can adjust rotor balance and speed transition times for customized response⁹.

Boss's own articles suggest pushing the Drive control "to conjure a more harmonically saturated sound redolent of psychedelic rock and amped-up acid jazz"¹⁰¹¹, and remind readers the pedal "isn't made solely for guitarists; it combines beautifully with synths, strings, and even vocals"¹¹.

External control

Beyond the onboard switches, the RT-2 supports advanced control with external footswitches or an expression pedal for speed, brake and other functions². Guitar World's Alex Lynham found this is where the pedal earns its keep for vibe-style playing: "It's possible to attach an expression pedal to control the rate. Doing so results in something that can replace a Uni-Vibe on your board"⁵.

History: from the RT-20 to the RT-2

The RT-2 is a return to a concept Boss had already visited. The RT-20 Rotary Ensemble, launched in 2005 as part of the Twin Pedal Series, brought the swirling sound of a rotary speaker into pedalboard reach, and stayed in production until 2019¹. Guitar.com reported the original was discontinued in 2019 and that Boss "has revisited the concept now in classic compact" form⁸.

Much of the RT-2's tonal DNA traces directly back to the RT-20¹. The two differ in format and features: the RT-20 was a larger twin-pedal unit with four modes, three classic Leslie rotary speaker cabinet tones plus a sound based around the Uni-Vibe, and an input for the optional EV-5 expression pedal for manual speed changes¹². It also ran on six AA-size alkaline batteries¹². The RT-2 drops the dedicated Uni-Vibe mode, moves to the compact single-pedal format, and runs on a single 9V battery or adapter⁵.

What reviewers said

Guitar World's Alex Lynham reviewed the RT-2 and summed up both its strengths and its limits⁵:

Alex Lynham, Guitar World⁵

His verdict list praised the "excellent sounding rotary effect" and noted that "it is not cheap but has everything you'd want from a compact rotating speaker emulator," while his criticism was that "more notable differences between the modes would be welcome"⁵. The review also records the pedal as made in Malaysia⁵.

At launch, Guitar World's Jonathan Horsley confirmed availability and the $239 price³, and MusicRadar reported the same US price with a UK price of £229¹³. Guitar.com's launch coverage gave the retail price as $239.99⁸; the two figures differ only in the cents, and both date from July 2025.

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