Above is a late model Arp 2600 (2601)

Most likely from 1976 according to this reputable web site

Arp 2600 Versions and History

This is an early version of the Arp 2601 with the Moog 4012 filter encapsulated

but most other modules are un encapsulated. Inside this Arp 2600

Below is the left side

Below is the right side of the Arp 2600

Below is a close up view of the top left of the Arp 2600

Below is a close up view of the VCO 2 and VCO3 of the Arp 2600

OSC Sync Switches at top, Middle position no sync,

Other 2 positions = synced to other 2 OSCs

Below is a close up view of the filter and envelope of the Arp 2600

Five audio inputs to the filter. Three control inputs

Below is a close up of the output section of the Arp 2600

Below is a close up of the bottom left of the Arp 2600

Below is a close up of the Voltage Processors and the Sample and Hold of the arp 2600

Below is a close up of the bottom right of the arp 2600

Below is the keyboard of the Arp 2600

Below The Arp 2600 in its cases and ready to go

Above tag on bottom side of main unit -Arp Model 2601 Synthesizer S/N 2601-0064

Below nestled in its own flight case with 1 inch foam on all sides

Below the Keyboard in its case

Page 2 Inside the Arp 2600