A few years back, Dean Miller created the Tele Servo Bender, a modified guitar that used servos to sound like a lap steel. His latest project moves to the low end, with a self-contained, battery powered FM Synth Bass with four voices and six operators. And lots of LEDs.

The FM Synth is built around a sliced acrylic cylinder that was cut at a certain angle to give a taper. The four strings that you might find on a traditional electric bass have been replaced with 500 mm (19.6 in) ThinPot Linear Position Sensors that sit in grooves so that they're flush with the neck, which is also home to four potentiometers. Behind the neck, Miller has secured 120 addressable LEDs that can supply an onstage light show or set to fire up when a fretting finger is detected.

The brains of the operation is a Blackfin+ DSP (digital signal processor) running an FM synthesis library. Miller says the DSP is similar to a general purpose microcontroller but designed specifically to handle digital signals, such as audio or video.

"The DSP CPU will have specific instructions for common signal processing tasks like fractional multiplies, complex multiplies, will have hardware support for looping without wasting CPU cycles, and hardware support for generating addresses of circular buffers without wasting clock cycles among other things," he said recently on a Reddit post.

The "strings" are tapped and slapped by the picking hand on a roughly smartphone-sized custom trigger area.

The FM Synth is an impressive one-off DIY build and not available to buy, but you can see it in action in the video below.