Design History

The original concept for the Resonator began while experimenting with a DIY spring reverb project. Using the amplifier and circuitry from the reverb setup, I replaced the spring with two strings and a cheap tactile transducer (essentially a stick-on speaker) mounted onto a rack tom using scrap wood and whatever parts I had on hand.

One of the earliest challenges was finding a way to transfer vibration into guitar strings. Unlike the loose springs used in traditional reverb units, guitar strings require significant tension to stay in tune, making them far more difficult to excite. Borrowing inspiration from the design of a banjo, I used a drum skin as a flexible surface to provide tension for the bridge and allow vibrations.

To my surprise, the prototype actually worked, although only when driven beyond what such small and cheap parts could manage so it didn't work for long.

It was clear that the idea had potential but it needed many more strings than could fit on the small drum, leading to a long period of sketching and concept development. Although eager to keep building, life pushed the project aside for several years, until eventually I had the space, tools, and opportunity to return to it properly.

In the years following the initial concept, I continued playing in various bands while regularly revisiting the idea and refining its design in the background. It wasn’t until I moved into a warehouse with an informal workshop and music studio that I finally had the space and time to return to building it properly.

At that point, I settled on a layout of two rows of seven strings, which allowed for tuning up to two octaves of a scale. One of the most significant developments in this version was the introduction of a floating bridge system that clamps directly onto the strings. This idea was inspired by the type of capo used on lap steel guitars, where the strings sit too far from the fretboard for a conventional capo to function.

By mounting the transducer onto a secondary floating bridge, I was able to transfer vibration into the strings while avoiding the spatial and tuning limitations of a drum skin. This made it possible to fit many more strings into a much more compact area.

The main limitation of this design turned out to be the available power of suitable tactile transducers. The high tension created by multiple strings significantly increases resistance to vibration, requiring a substantial amount of power to drive the system effectively. I ended up burning out four transducers before concluding they weren’t a viable long-term solution.

Although I did manage to use this model on a few recordings before it failed, it ultimately spent more time stored in the workshop than in active use. Those recordings can be found at the bottom of the Gallery page.

At this stage, I became interested in how the Ebow works and began exploring whether it might be possible to use direct magnetic induction to vibrate the strings. The idea was to build a system where a magnet and coil assembly could push and pull the strings themselves with just the magnetic field. 

During this research, I came across a PhD project that applied a similar concept to a grand piano. However, that approach required a dedicated pickup, driver, and amplifier for every individual string, making it impractical for my purposes.

I experimented with a range of more unconventional ideas, including modified guitar pickups used as miniature speakers, but none of them produced effective results. It seemed that the magnetic field simply didn’t have enough “grip” on the strings unless it was positioned so close that it risked physical contact once the strings began to vibrate.

I then explored the idea of using a DC electromagnet mounted to the instrument body, acting on a steel disk clamped to the strings. My thought was that, by driving it like a speaker with a power amplifier rather than a DC supply, it might generate usable vibration. However, even with significant power, and a substantial amount of heat, the resulting string movement was minimal.

Although these driver concepts didn’t ultimately work, the experimentation helped move the project forward in other ways, including the introduction of cello fine tuners, which made precise tuning significantly more practical.

While exploring magnetic induction and coil winding, I was also developing the tuning system for the instrument. The goal was to keep the Resonator chromatically tuned while providing a reliable way to mute unwanted strings.

Early inspiration came from the Autoharp, which uses button-activated, felt-tipped levers to selectively dampen strings. This led to a simple way of thinking about the system: if you map all the strings along one axis and key signatures along the other, a clear and repeatable pattern emerges showing which strings should be active or muted for each key.

The real insight came from arranging the key signatures in the circle of fifths. In this layout, all keys that share a given note sit next to each other, and moving from one key to the next only changes a single note. This creates a continuous, structured relationship across all twelve keys.

From there, I realised this pattern could be wrapped into a cylindrical form and translated into a camshaft mechanism to drive the muting system mechanically. A prototype mock-up confirmed the concept in principle, but a system of this nature requires extremely tight tolerances and precise construction to function reliably.

At that point I had left the warehouse space, and it would be almost two years before I had access to a workshop again.