Synthesizer design and manufacturing company founded by Alan R. Pearlman, and the second largest such company after Moog Music for most of the 1970s. Originally founded under the name "Tonus" in 1968, the company was renamed using founder Pearlman's initials when it released its first product, the lavish and expensive 2500 modular system, in 1970. Despite the 2500's high cost, it soon became popular with university music departments. ARP's next product, the semi-modular 2600, provided many of the functions of a modular in a smaller pre-configured case; it established ARP among first-rank synth and keyboard players of the decade.