Yamaha S90

The Yamaha S90 is a professional-grade synthesizer keyboard released by Yamaha in 1998. It is a 61-key, velocity-sensitive keyboard with a built-in 16-track sequencer and a variety of sound-generating capabilities. It has been used by a variety of artists, including Herbie Hancock, John Legend, and Coldplay.

The Yamaha S90 works by allowing users to create and manipulate sounds using a variety of parameters. It has a wide range of sound-generating capabilities, including FM synthesis, waveform synthesis, and sample-based synthesis. It also has a variety of effects, including reverb, chorus, and delay. Additionally, it has a built-in 16-track sequencer, allowing users to create complex musical arrangements.