Korg Z1

The Korg Z1 is a synthesizer from 1997 (manufactured until 1999), which uses multiple synthesis forms including physical and analog modelling synthesis based on the Korg OASYS.

Peter Gabriel was introduced to the Z1 by synthesizer expert Paul Wiffen, who was working for Korg at the time - this was during the recording of Up or OVO in the late 1990s. Paul felt the 'Decimate' effect on the synth suited Peter's tastes for crude sounds, so he reached out to one of Peter's engineers about it and was invited to bring the synth to the studio. There he ended up doing treatments on one of Peter's vocals via feeding through the filter for a harsher and more menacing sound. Previously, Brian Eno did treatments in a similar way (referred to as "Enossification") on Peter's vocals in places of Genesis' The Lamb Lies Down On Broadway in 1974.

However, Paul's vocal treatments didn't make the final cut on either Up or OVO. Perhaps these were lost as the songs evolved into their final iterations, or it featured on a song that was omitted.

Further info

 * Wikipedia