En If Charlie Parker… dicen que Paul McCartney está jugando con este Tubon entre bambalinas de un concierto en Alemania pero en otros sitios dicen que el instrumento en cuestión pertenecía a un grupo sueco llamado The Shakers que estaba examinando. Sea como sea, tampoco se encuentra mucha información sobre el aparato más allá del blog de un aficionado que hace unos años estaba reconstruyendo uno de estos instrumentos:
The Tubon is a tube-shaped electronic monophonic instrument with a guitar-strap. It is primary a bass instrument with preset sounds like tuba, contrabass, electric bass etc, and is played staccato. It was made in the late ’60s in Gothenburg, Sweden by a company called Joh Mustad AB. The same company also made the tube organs Bergman Klavitron and Klavinette. The Mustad Tubons also seem to have been sold in the UK under the «Livingston» brand. Numerous swedish pop and rock acts used this instrument in the late 60s and early 70s, but there are also images showing Paul mcCartney playing one. However, I find no evidence that the Tubon actually found its way onto a Beatles record. Ralf Hütter in Kraftwerk also used one of these in their early years as a bizarre kraut band.