It sports clear text labels and front panel screen printed graphics indicating the function of different sections of controls, and the signal flow between them.

The following year, ARP adopted this improvement and introduced the Model 3620 duo-phonic keyboard, which also included delayed vibrato as well as single and multiple triggering functionality.

Model 2600 “Blue Meanie” (early 1971): The earliest 2600s were assembled in a small facility on Kenneth Street in Newton Highlands, Massachusetts, during ARP's infancy as a company.

[5] The first significant user of the 2600 was Edgar Winter, who connected the keyboard controller of the 2600 to the main unit via a long extension cord, allowing him to wear the synth around his neck like a keytar.

Dubbed the TTSH ("Two Thousand Six Hundred"), this project allows a hobbyist to build their own synthesizer for a fraction of the price ($499USD for a panel and PCB set) of the original.

The re-issue adds features, including: the ability to select between the 4012 and 4072 filter types found in the 1970s versions, balanced XLR outputs, MIDI, a basic sequencer / arpeggiator, and a flight case for travel.