Onde Magnétique is a boutique instrument company founded by synthesist and sound designer Scott Campbell, hand-building cassette-based electronic instruments in New Orleans, Louisiana. The shop's flagship product is the OM-1 Cassette Synthesizer, an analog instrument that exploits the way a sustained tone recorded to tape changes pitch as the tape's playback speed shifts. Loosely inspired by the Mellotron and the Ondes Martenot, the OM-1 plays back a special cassette of continuous tones through eight pressure-sensitive keys, each paired with a tuning knob, and accepts CV/Gate input for control over pitch and volume from external sequencers.

Alongside the OM-1, which has been issued in aluminum, white, and black-and-gold finishes, the company also produces a Cassette Tape Echo. The instruments have drawn attention from outlets like MusicRadar, FACT Magazine, Synthtopia, and New Atlas, and have found a following among ambient and experimental musicians interested in the textures of magnetic tape.

Onde Magnétique has 2 products cataloged on Equipboard, including Effects Processors and Tabletop Synthesizers. Their gear is featured by 3 artists, with the strongest followings in Electronic, Stage & Screen, and Pop. Notable users include Junkie XL, Andrew Huang, and Drum & Lace.