The Circle Guitar: creating new kinds of music

The Circle Guitar is a conventional electric guitar that hosts a spinning sequencer wheel, able to strike the strings at speed creating rhythms up to 300bpm and adding multiple layers of sound. This new instrument relies on a control and motion system that achieves precision in rhythm control. 

The electric guitar has been the iconic instrument of popular music since the early 1950s. However, you may not have seen – or heard – an electric guitar quite like this. Instead of strumming or plucking the guitar in a conventional way, the Circle Guitar automatically strikes the strings at speed via a spinning, motorised wheel. 

The wheel can host up to 16 magnetically attached ‘picks’, the small tool guitarists use to pluck or strum the strings. This array strikes the strings on each revolution, with the speed of the wheel corresponding to a player-controlled beat of up to 300bpm. 

While the automatic string striking of the spinning wheel creates rhythms impossible to achieve by hand, this approach also frees up the hand normally used for strumming or plucking, enabling interaction with the guitar in new ways, such as two-handed chords or vibrato.  

What’s more, the guitar’s pickups, the transducers that capture the vibrations of the strings converting them into a signal that can be amplified, can segregate the sound of each individual string. Combining these features, the resulting effect creates a sound entirely different to a normal guitar. 

“Occasionally, you see or get to play something that makes you think in a totally different way. This is an extraordinary new guitar, and I’ve already put an order in to buy the first one,” says Ed O’Brien, guitarist with Radiohead, who has trialled an early version of the Circle Guitar. 

Circle Guitar, an innovative new instrument

A rhythm machine

The Circle Guitar was invented by the founder of Circle Instruments, Anthony Dickens, who describes the guitar as a rhythm machine. 

“For years I’ve been trying to find an original approach to electronic music production, and I’ve spent years wondering how I could make music influence design, and vice versa,” says Anthony. “This project started with the idea: when you strum the guitar, what if that strum never ended?” 

That’s when Anthony came upon the wheel concept and shortly found himself in a guitar shop where he customised a standard guitar design, adding a handle-driven wheel with multiple plectrums. Fast forward six years and Anthony’s design is electronically driven and programmed, with prototypes now in a second phase of development heading towards production.

The sequencer wheel can be controlled using three different modes. Producer Mode uses a DAW (digital audio workstation) or a hardware sequencer to program and trigger MIDI (musical instrument digital interface) note patterns to move the wheel; Pedal Mode uses a MIDI pedal to trigger the movement, and finally, Player Mode will work as a standalone mode where the player can trigger rhythms on the guitar itself, using a tap-tempo to set the speed and a set of buttons to change the wheel’s behaviour. 

The wheel speed can vary quickly to create different rhythms, stop-start strums, varying speed rolls, and swing patterns, achieving broad musical styles ranging from punk to ambient and techno to hip hop. Toggle switches can also fade the volume of each string up and down, and strings can also be turned on and off individually to play an ordered sequence of notes from a chord, known as an arpeggio (“like Donna Summer’s ‘I Feel Love’,” adds Anthony). 

Playing in a way that the human guitarist cannot

Producer Mode opens the potential of a producer working with the guitarist to manipulate the sound while the guitarist is playing, creating a new, collaborative way of writing music together.

“The whole purpose is to create new kinds of guitar music,” says Anthony. “We can make the wheel spin exponentially and logarithmically, strumming in ways the human hand cannot. As the wheel is perfectly in time, and with several audio channels arpeggiating each string of the guitar, we can even make it sound like multiple guitarists playing different things, all together in time.”

Yet for the other-worldly sounds that the Circle Guitar can create, and the futuristic appeal of the spinning sequencer wheel at the centre of the guitar’s body, the instrument still looks very much like a traditional electric guitar.

“When you create something new, you've got to bring people with you,” says Anthony. “If you take an accepted design and you move it too far beyond what people expect, there's resistance and people won't believe in it, so I wanted to make sure that the Circle Guitar was a familiar shape.”

The guitar is also manufactured from traditional materials, with the body made from alder, the neck made from maple, and the neck’s fretboard made from sustainable Richlite. The sequencer wheel and electronics are machined from aluminium and housed within the body of the guitar, along with Circle Instrument’s proprietary PCB and control programming for the maxon motor responsible for the wheel’s motion.

Enables complex rhythms beyond manual play

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Motion control and rhythm coordination

“In terms of control, the challenge was making the sequencer run positionally, in time, and at the right speed. Orchestrating this trio of factors is essential to achieve the precision, as well as the variation, in rhythm coordination,” says Anthony. 

To generate smooth motion, the role of the motor, driving the sequencer wheel via a belt, is crucial. For the first prototypes of the Circle Guitar, Circle Instruments over specified the design of the motor, selecting a device with excess torque for requirements, and a design that was too fast, where a beat above 300bpm becomes inaudible to distinguish. This oversized motor also expanded the footprint of the instrument.

Working with maxon, engineers have now specified a compact, flat design brushless DC motor that fits within the original contours of the guitar’s body. The motor comprises an innovative iron core winding and high performance, rare-earth magnets that optimise motion precision, enabling Circle Guitar to seamlessly switch between various rhythms of alternating speed. The compact motor design will also help reduce the overall production cost of the Circle Guitar. 

Photos copyright of Anthony Dickens and Simon Whitehead.