The Electronic Music Studios EMS Synthi VCS3, aka The Putney, is a portable synthesizer introduced in 1969. It was designed by David Cockerell.

Wendy Carlos had this to say about the Synthi VCS3:

The PUTNEY is a real toy. Its components are highly unstable/unpredictable and the selection made is highly gimmick orientated and does not by any stretch of the mind permit any subtle sounds & exp. to be constructed. It also has a so-called touch-sensitive keyboard which has to be tried to be believed, it’s that awful. No feel or physical feedback at all (as there is in a piano, for example); again, another great concept worked out in ignorance (and the one I tried worked backwards: softer touch = louder sounds!) But it is small & portable & groups might like it for special effects.

Notable users include: Brian Eno, The Who, Pink Floyd, TONTO’s Expanding Head Band, Jean Michel Jarre, The Chemical Brothers & Tangerine Dream.

The EMS Synthi VCS3 originally retailed for £330. Amazingly, it’s still in production (see discussion in comments).

Here’s another EMS Synthi VCS3 demo video:

Features:

A solid Aformosia cabinet housed the following modules, interconnected by means of a matrix patchboard:

• 3 x Voltage Controlled Oscillators.
• Noise Generator.
• 2 x Input Amplifiers.
• Ring Modulator.
• Voltage Controlled Low Pass Filter.
• Trapezoid Envelope Generator.
• Voltage Controlled Reverberation.
• Meter.
• 2 x Stereo Output Amplifiers.
• Joystick.

Resources:

• EMS still sells the EMS Synthi VCS3
• Keyboard’s Mark Vail on the EMS VCS3
• A guide to EMS VCS3 mods and servicing