VP330 Vocoder Plus was another unique instrument in the history
of electronic keyboards.
It was essentially a string synth
with a simple vocoder built in. Many people used it for the vocoder
(Phil Collins on "In The Air Tonight" for example) but
many used it for its mellow 'choir' preset (constructed by filtering
the raw oscillators of the string section to create an 'aaah' sound).
Tony Banks of Genesis replaced his Mellotron with a Vocoder Plus
on tour to have a more portable and reliable choir sound in tracks
such as 'Los Endos' (it didn't sound anywhere as majestic though!)
and the choir sound was a favourite of the Japanese fusion band