ARP 2500（1970）

ARP Instruments Inc. (subsequently referred to as ARP) was founded in 1969 and based in the state of Massachusetts in the U.S. The name came from the initials of one of the founders, Alan Robert Pearlman. Co-founders included Lewis G. Pollock and David Friend. It was an age when gigantic modular systems dominated the synthesizer world. However, the tuning of these instruments was usually unstable and each manufacturer struggled with this problem. ARP decided that the development of a highly stable oscillator was important so they dedicated research and product development towards achieving this goal.

The model they first developed was the ARP 2500, a large modular synthesizer. The design on this model used a large number of matrix switches, placed above and below the knobs and switches of the panel, replacing the patch cord design that was used on other manufacturers' products of the time. This unique design strategy eliminated the complex tangles of patch cords that obscured the panel. Thanks to ARP's research, tuning was now extremely stable and the ARP 2500 became a hit product as a research tool for universities. It even appeared in the film “Close Encounters of the Third Kind” (1977) as a device used to communicate with an alien spacecraft.

ARP makes a great leap: the ARP 2600

ARP 2600 (1971)

The following year, 1971, marked the appearance of what was to become one of ARP's most iconic instruments: the ARP 2600. The ARP 2600 was a mid-sized synth that was more compact than the ARP 2500, more portable, and more streamlined to program. It had a three-VCO architecture in which each module was connected internally, or “normalled”, while allowing extremely complex sounds to be created by using patch cables to “break” these normalled connections. Its wide possibilities for sound design earned it a place first in the educational market, and then in recordings by numerous musicians as well as in film music production. (The most well-known example is that the voice of R2-D2 in the film "Star Wars" was created using an ARP 2600!) Another major feature rarely seen in other synths was that the ARP 2600 was equipped with built-in speakers and a spring reverb. This gave the 2600 a unique sound and also a highly personal playing experience, which appealed to artists such as Stevie Wonder and Joe Zawinul.

After it went on sale in 1971, the ARP 2600 continued to evolve over the course of its lifetime in both specification and appearance. The first production run of the 2600 in 1971 featured a distinctive metal body with blue panels, nicknamed the Blue Marvin. The same year, there was a model change that was popularly known as the 2600C Gray Meanie due to its metal body and gray panel. Subsequently another model change occurred, resulting in the 2600P, the now widely familiar suitcase-type unit in which the sound engine and keyboard section are in separate pieces. Minor improvements continued, and models later than 1975 are called the 2601. In the latter half of the 1970s, the keyboard also changed from the previous 3604 to the duophonic-capable 3620. In 1977, a new version adopted the black panel with orange silk-screening that was to become ARP's signature color.