The Akai GX-635 D is a reel-to-reel tape recorder manufactured by Akai in the 1970s. It is a stereo three-head system with auto-reverse capability. The GX-635 D features a built-in Dolby NR system for noise reduction and has separate left and right channel recording level controls. It also has VU meters for monitoring the input and output levels. The tape speed can be adjusted between 7.5 and 15 inches per second. The GX-635 D has both balanced and unbalanced input/output connections and supports various tape reel sizes.