GX635D

About the GX635D

Manufactured in Japan in the late 1970s, the Akai GX-635D is a 4‑track, 2‑channel stereo/monaural open‑reel tape deck with auto‑reverse playback and bi‑directional recording. It accepts up to 10.5‑inch reels via adapter hubs and provides two tape speeds, 3¾ and 7½ ips, with pitch control. The transport uses a 3‑motor configuration (one AC servo capstan motor and two reel motors) and a 6‑head layout with two GX (Glass & Crystal Ferrite) record heads, two GX playback heads, and two erase heads, giving very low wear and long‑term head stability. Frequency response extends up to about 27 kHz at 7½ ips, with wow and flutter around 0.03–0.04% and signal‑to‑noise ratio roughly 62–70 dB, placing the deck among Akai’s higher‑performance consumer machines of its era.