(Often abbreviated DSI) A synthesizer manufacturer founded by Dave Smith, who was also a co-founder of Sequential Circuits. The company released its first product, the Evolver, in 2002; several variations on the Evolver followed over the next few years. In 2008, they released the Prophet 08, Smith's modern variation on the classic Prophet-5. Products that followed included the Mopho, a low-cost monophonic synth sharing the Prophet 08's voice architecture, and the Tetra, a four-voice version of the Mopho. In 2011, the company introduced the Tempest, a drum machine based on Smith's ongoing collaboration with Roger Linn.
In 2015, DSI introduced the Prophet-12 , a op of the line synth incorporating many of the features of the discontinued Poly Evolver. It was a hybrid synth with a digital oscillator section, but analog VCFs and VCAs.
In 2018, DSI changed its name to Sequential Inc. (without the "Circuits), after Yamaha, which had purchased the assets of the original Sequential Circuits in 1987, returned the name to Smith. (Yamaha was reported to have made this gesture at the insistence of Roland's Ikutaro Kakehashi). The Prophet-6, a re-creation of the Prophet-5 with one additional voice and some other modern features, was the first product released under the new Sequential name. Smith then collaborated with Tom Oberheim on the OB-6, a modern version of the Oberheim OB-8. This was released under the Oberheim name (after Gibson returned the name and trademarks to Tom Oberheim), but was manufactured and marketed by Sequential. Since then, Sequential has issued a bevy of new products. The "Rev4" Prophet-5 is a re-creation of the original, accompanied by a new single-manual version of the Prophet-10; the Prophet Rev2; the Prophet X with sampling capability, and the Pro 3 monphonic synth.
DSI/Sequential has been noted for its successes at restarting production of several Curtis and SSM integrated circuit designs from the 1980s for use in its current products. They commissioned Dave Rossum to design the 2140 VCF, a new version of the SSM 2040.