(Not to be confused with the Synclavier) A computer-controlled polyphonic analog synthesizer originally designed by film-score musician David McLey, circa 1975. The McLeyvier hardware included a keyboard console with a video terminal, and a separate equipment rack containing a DEC LSI-11/23 minicomputer and the sound-producing hardware boards. Specifications for the synth are hard to find, but apparently all routing between components was controllable by the computer. The computer and its operating system software was, by most descriptions, the outstanding feature of the synth. McLey designed the software such that it could do sequencing, patch control, score generation, and a wide variety of transformations on the music being created.
The McLeyvier was developed and offered by a company named Hazelcom Industries in Toronto, and begin appearing at trade shows starting around 1980. Reports from the time suggest that Hazelcom brought it to market prematurely; the software was not finished and crashes during demonstrations were frequent, which put off potential buyers. McLey eventually lost interest in the project, and Hazelcom hired electronic musician / computer scientist Laurie Speigel to be the lead software engineer for the project. Speigel worked extensively with the synth herself, producing music with it as part of the process of shaking out the software. (Of those times, Speigel said later: "In some ways the McLeyvier was absolutely wonderful. In other ways, it was absolutely infuriating.") Unfortunately, by the time Hazelcom was ready to start shipping McLeyviers, the Fairlight CMI had beaten it to market; the Fairlight had many of the same features and was a digital synth to boot. Hazelcom made a rush attempt to replace the McLeyvier's analog synth circuitry with digital, but they were too far behind; they eventually threw in the towel around 1985.
Comments by Speigel suggest that only about eight McLeyviers were completed. Very few musicians other than Speigel herself are known to have owned or worked with one. Canadian film composer Paul Hoffert was one; here is his opening them to the TV show The Hitchhiker, composed and performed on a McLeyvier. No McLeyviers are known to be in working condition today.