David Vorhaus’ Kaleidophon, an early electronic Unfretted instrument

David Vorhaus has been involved in electronic music since the late sixties after meeting with and later working with Delia Derbyshire and Brian Hodgson from the BBC Radiophonic Workshop.

Classically trained and playing double bass he admits he was not comfortable with keyboards so looked towards making an instrument that would allow him to control synthesised sounds.

David Vorhaus
David Vorhaus – picture © Marc Sethi

The Kaleidophon

Kaleidophon, close up – picture © Marc Sethi

The Kaleidophon in the picture above must date from 2000 onwards – evidenced by the blue LED indicator lamp. Earlier versions can be see in the video archive below. While it is not quite a fretless guitar, the playing technique is similar, it is a fascinating alternative.

In David’s own words….
I made the ribbons for the Kaleidophon using thermal paper which has a carbon underlay with a wax coating. I got hold of some of the material before they put the wax on and, amazingly, its resistance was quite linear. Obviously paper wasn’t robust enough so I got them to put it on plastic. Eventually these were made for me by the French Space Agency because the person who worked for Ozalid in the UK, who made the original strings for me, died and took the manufacturing secret with him.

The triggering is activated by pressing on the strings and the fingerboard is velocity-sensitive so you can hit it harder to get a louder note or a different effect. There are controllers at the bottom for the right hand and other devices such as chromatic switches to make it behave like a fretted instrument. It can also be semi-fretted, which corrects you if you’re close to the right note but still lets you do slides.

The instrument itself generates voltage control, but I can feed it into my CV-to-MIDI converter and use it to control just about anything. – David Vorhaus

The instrument was a joint winner of an International Electronic Music Instrument Competition in Austria: David shared the prize with the Fairlight CMI, and he soon became close friends with Fairlight designer Peter Vogel, who went on to help David with some of his designs.

Video archive

David Vorhaus plays the Kaleidophon
Filmed by Coldcut’s Matt Black


David Vorhaus talks about two of his analogue inventions – the MANIAC analogue sequencer, and the Kaleidophon from 1979.


1976 BBC Tomorrow’s World – Kaleidophon

1976: Tomorrow's World: Kaleidophon

#OTD 1976: BBC Archive's rock band is now auditioning for a Kaleidophon player. You must be this good, and have your own Kaleidophon. You know – a Kaleidophon? "The mixed marriage between a violin and a plastic drainpipe"

Posted by BBC Archive on Friday, 2 December 2016



Sound on Sound – February 2002

Red Bull Music Academy


More Unfretted Instruments

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