The Siel Expander 80 is a vintage analog synthesizer from the 1980s. It was used by a variety of artists, including Depeche Mode, New Order, and Jean-Michel Jarre. The Expander 80 is a monophonic synthesizer with two oscillators, a low-pass filter, and an envelope generator. It also features a built-in chorus effect and a noise generator. The Expander 80 is capable of producing a wide range of sounds, from warm and mellow to aggressive and distorted. It is also capable of creating complex soundscapes and textures.