The Gibson Clavioline is a single manual mini-key piano attachment with a tube preamp and amplifier, made from about 1934-1965. The sound made famous in Telstar and in The Beatles' 'Baby I'm A Rich Man', it uses a basic square wave.

The original design was by Constant Martin in France, and many companies licensed it. Selmer were perhaps the most famous maker in the UK, but Jorgensen in Germany was another, and Gibson in the US. The common design feature was a metal-cased keyboard, complete with internal tube tone-forming circuitry. The case attached by metal sliders to rails that could be screwed to the underside of your piano keyboard - or you could use the Clavioline as a stand-alone instrument on a metal stand. There is a Set of rocker switches underneath the keyboard for tone choice. The tube amplifier and speaker are in a case, which the Clavioline keyboard folds into for transport.

Although the tone is quite variable, the sound is distinctive, and instantly recognizable, due mainly to the simple envelope employed - and maybe also to its monophonic nature, which somehow gave melodies a different feel from exactly the same line played on an organ. It may be the glitches which provide its charm. Gibson licensed the Clavioline design from Constant Martin and made the American Clavioline version in 1954. Al Kooper plays one on BS&T's first album, Child is Father to the Man, and I think the specific tune is 'Meagan's Gypsy Eyes.' Also used on 'Sweet Pea' by Tommy Roe, 'Just a Mirage', Tommy James, and Del Shannon's 'Runaway'. A really cool instrument, it's the big brother to the Clavioline used on 'Telstar'.

Good condition, functional but has issues. Powers up, although the power light on the amplifier does not light. Keys play, but seem to just play one pitch, with a variable pitch underneath, and a quavering quality. The tone switches do change the sound, volume control works, and the octave switch works.

Includes the tube amplifier / speaker, which forms the case that holds the Clavioline, the Clavioline keyboard, 3-legged tripod stand, and power cable with split-off multi-pin cable that powers the Clavioline. Also has the service manual (which appears to be original). And includes the expression knee-lever, which is integral to the sound of the Clavioline.

Full pictures are here, along with a video of the instrument being played:

https://drive.google.com/drive/folders/1rSXB0kPlwqEIRB92uAWtyN6DwBvGPExU?usp=drive_link

Great review at Sound on Sound:

https://www.soundonsound.com/reviews/story-clavioline