Created by Wirral engineer Tom Hardiment, and tested by his partner Cat, the Groovetube is a new prototype plasma synthesizer. The instrument makes wild and crazy sounds with fluorescent tubes, and can be controlled with a magnet.
Lit fluorescent tubes are filled with plasma – a low pressure electrified gas that can make oscillations at audible frequencies. With suitable control over the plasma in the tube, they found this instability could make an amazing range of sounds… that could also be controlled with a magnet! (Listen to their videos with headphones, to hear details of the sound).
Playing with sound created in a glowing tube is tactile, surprising and absorbing, and they decided to develop a new kind of electronic instrument.
Groovetube
A prototype was demonstrated and a first-generation machine made available for pre-order on Kickstarter for people to try out a new way to make noise – an experimental machine to be experimented with! This has helped support its development into a proper synthesiser, which is now complete – the first batch of instruments will be built and delivered over the next few weeks.
It is a plasmaphone, and so an electronic instrument. It is also a bit like an acoustic wind instrument in having sound produced by waves in a tube, although they are different kinds of wave. Some of the noises do sound like wind instruments and even rushing air.
How does it work? Plasma is excited in the tube using a low-power RF generator. The machine is basically a valve preamp with electrical current sourced from the plasma tube, which introduces noise to affect the character of the sound. The nature of the plasma noise is controlled by regulating the amount of plasma in the tube and level of current passed through the tube. The magnet effect works because magnetic fields bend electron paths, making them more efficient in the plasma. At locations along the tube this has a different effect on the discharge as a whole, and so the sound.
About the developers
Tom and Cat share a passion for electronic and experimental music. Cat has tested the machine’s performance throughout its initial development, making her a pioneer voyager in plasma sound, while Tom has been responsible for creative vision and engineering. They live with their family in the Northwest of England.