Boss RT-20 Rotary Ensemble Pedal

COSM-modeled Rotary Speaker Emulation Pedal with Overdrive Effects
Boss RT-20 Rotary Ensemble Pedal image 1
Boss RT-20 Rotary Ensemble Pedal image 1
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Boss RT-20 Rotary Ensemble Pedal
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The New Standard in Rotary Speaker Simulation!

From the Beatles to Jeff Beck, Santana to Stevie Ray Vaughan, many guitar greats have embraced the rotary speaker sound onstage and in the studio. BOSS proudly announces the newest member of its Twin Pedal series - the RT-20 Rotary Sound Processor. Employing COSM modeling technology, the RT-20 authentically reproduces classic rotary-speaker sounds. It offers adjustable Rise Time, Horn and Bass seed, Overdrive, and more. And not just for classic twirl, the BOSS RT-20 can be used to create unique overdrive and pulsating effects as well. This pedal sounds amazing, and offers a stunning graphical view of the virtual rotors on its built-in display.

BOSS RT-20 Rotary Sound Processor at a Glance:
  • Classic rotary speaker sounds using COSM technology
  • Easy to connect both guitars and keyboards
  • Stunning virtual rotor display

Classic rotary speaker sounds using COSM technology
Years of intensive research and development have made Roland and BOSS world leaders in modeling technology. Roland's breakthrough Composite Object Sound Modeling (COSM) uses the advantages of multiple modeling methods, and succeeds in accurately emulating existing sounds as well as producing sounds that have never before been created. With the BOSS RT-20, COSM is used to simulate classic rotary characteristics, and beyond. The virtual horn and bass speaker can be independently adjusted, while the BOSS RT-20's unique graphic display provides a real-time view of the rotation pattern and speed.

Easy to connect both guitars and keyboards
Guitars and keyboards alike can be plugged into the Easy to connect both guitars and keyboards. Use the Drive Type switch to optimize the effects for guitar or keyboard. Surround your listeners in animated sound with the RT-20's dual outputs, which enable true stereo effects. Add color by adding an expression pedal (such as the new BOSS FV-500H/FV-500L, optional), which lets you control parameters such as rotation speed seamlessly from slow to fast in real time. The BOSS RT-20's phone jack is handy for private practice and experimentation.

Stunning virtual rotor display
Thanks to its stunning visual display, the BOSS RT-20 might be the most eye-catching pedal in BOSS history. The spinning lights don't just look cool, they also show the audio-rotation characteristics of the RT-20 in real time. The center of the display, illuminated in red light, represents the virtual horn. The outside ring, illuminated in blue, displays the rotation of the virtual bass speaker. It's attractive while also being informative!

BOSS RT-20 Rotary Sound Processor Features:
  • Authentic rotary speaker sounds by COSM technology
  • Slow/fast transition time is adjustable from gradual to rapid change, optional Expression pedal can control speed in real time
  • Onboard overdrive effects
  • Adjustable mix balance between treble rotor and bass rotor
  • 4 types of sounds, from standard rotary speaker effects to rock-oriented tones, UNI-V, and more
  • Guitar/Keyboard switch
  • Dazzling virtual-rotor display
Take your guitar or keyboard for a spin with the BOSS RT-20 Rotary Sound Processor!

Additional Media

BOSS RT-20 Owners Manual

Tech Specs

Pedal Type Stereo Rotary Speaker
Inputs 2 x Instrument
Outputs 2 x 1/4", 1 x TRS (Headphones)
Batteries 6 x AA
Height 2.25"
Width 6.8"
Depth 6.25"
Weight 2.8 lbs.
Power Supply Included No
Manufacturer Part Number RT-20

Customer Reviews

Based on 15 reviews
Write your review

Great Product

I purchased an RT-20 Rotary Ensemble back in July 2016 and have been pleased with everything about Sweetwater and the pedal. My sales engineer, Ben Clemmer, was great to deal with and the pedal has functioned flawlessly. No, it is not a 122, 145, or 147 Leslie but I believe the RT-20 is as close as any pedal can get to sounding like an actual Leslie speaker. The adjustable rise time and overdrive make this pedal truly authentic sounding. I would purchase it again and will buy more from Sweetwater.
Music background: 30+ years guitar and keyboards,

Rotary Bliss!!

Great Rotary pedal. Cool retro vibe. Spot on Leslie simulation. Great roland/boss pedal with COSM tech. Cool Pedal. I use it often.
Music background: Hobbyist, Composer

Sounds Like A Leslie

The Boss RT-20 is phenomenal. You could use it for both keys and guitar, but I strictly use it for guitar. One of my favorite guitar sounds is the sound Frampton got on his Frampton Comes Alive album. He got that sound using Leslie cabinets. I know this because I've seen him several times. This pedal allows you to get that same sound without having to lug around a Leslie and it's extremely simple to use. It's the coolest effect in my guitar rig.
Music background: Pro Musician


The RT-20 Is What I've Been Waiting For. It Is By Far The Best Leslie Simulator On The Market. I Own An Oberheim OB-3 And Along With The RT-20 It Sounds Like A Hammond B-3 Along With A 122 Leslie Speaker. WAY TO GO BOSS!!!!
Music background: Pro Keyboard Player

Rotary effecct that really sounds like a Leslie

Not only great rotay and Univibe sounds, but this tool with both pedals pressed at the smae time makes a great clean boost for my Taylor acoustic. I have the expression pedal for it and am also using one of the Boss Fender Tube Reverb pedals, nice combination. The natural distortion and Marshall type distorion are pretty good
Music background: Guitar player
See also: Boss, Boss Chorus Pedals