The ARP 2500 is the first product of ARP Instruments, Inc., built from 1970 to 1981. It is a monophonic analog modular synthesizer equipped with a set of sliding matrix switches above each module. These are the primary method of interconnecting modules. There are rows of 1/8" miniphone jacks at the end of each row of matrix switches, to interconnect rows of switches. The main 2500 cabinet can hold 12 modules, and optional wing cabinets can each hold 6. The matrix switch interconnection scheme allow any module's output to connect to any other module's input. This is unlike the patch cords of competitive units from Moog and Buchla which can obscure control knobs and associated markings, but it has the disadvantage of greater cross-talk.