Akai GX-635 DB is a reel-to-reel tape recorder manufactured by Akai in the 1970s. It is a two-track, two-channel recorder capable of recording and playing back in both stereo and mono. The GX-635 DB features a three-motor transport system for improved stability and accuracy. It has multiple speed options including 7.5 and 15 inches per second. The reel sizes it supports are 5-inch, 7-inch, and 10.5-inch. The GX-635 DB also includes features like auto-reverse, tape tension control, and sound-on-sound recording. It has both line inputs and outputs for connecting to other audio equipment. The machine has gained popularity among vintage audio enthusiasts for its sound quality and durability.