Akai GX-635D 4-Track Auto-Reverse Stereo Tape Deck — 6 GX Heads, 3 Motors — Serviced — Original Wooden Case

The Akai GX-635D is widely regarded as one of the finest reel-to-reel decks Akai ever produced — part of what enthusiasts fondly call Akai's "holy trinity" — and this is a clean, serviced example ready for many more years of use.

This Unit

Professionally evaluated with all functions tested and passed. Basic preventive maintenance completed: fully lubricated, new belts, tested for functionality, and transport alignment performed. Cosmetically the unit presents very well overall. There is a small imperfect repair to the bottom-right corner of the wooden case, visible under certain lighting conditions (see photo 9), but overall the unit presents very well with no other significant cosmetic issues. Multi-voltage design (110/120/220/240V), currently configured for US current. Please see video demonstrating basic functions.

About the GX-635D

Introduced in 1979, the GX-635D represents Akai at the height of its engineering. It is built around the technologies that earned Akai its reputation for longevity:

Akai's legendary GX (Glass & Crystal Ferrite) heads in a 6-head configuration — two GX record, two GX playback, and two erase heads, enabling full auto-reverse recording and playback in both directions. The GX head design is renowned for exceptional wear resistance; these heads are famous for measuring nearly like-new even after decades of service, which is a substantial part of this deck's enduring appeal and value.

Three-motor direct-drive transport — one AC servo motor for direct-drive capstan control and two eddy-current outer-rotor reel motors. This delivers stable, precise tape motion and the smooth, reliable transport Akai built its name on.

Feather-touch logic control for the transport, with both-way (bi-directional) recording, real-time counter (up to 99 min), pitch control (±6%), REC mute with timing, timer-start standby, independent left/right record-level controls, mic and line inputs, and switchable tape/monitor settings. The 4-track quarter-track format maximizes tape efficiency and ensures compatibility with the vast library of prerecorded and consumer-recorded quarter-track tapes.

The GX-635D handles up to 10.5-inch reels and presents beautifully in its wood-sided case with the classic Akai silver faceplate.

Verified Specifications

• Track system: 4-track, 2-channel stereo, auto-reverse (both-way record & playback)
• Heads: 6 total — 2 × GX record, 2 × GX playback, 2 × erase
• Motors: 3 — 1 × AC servo direct-drive capstan, 2 × eddy-current direct-drive reel motors
• Tape speeds: 7½ IPS (19 cm/s) and 3¾ IPS (9.5 cm/s)
• Reel capacity: up to 10.5 inch reels
• Frequency response: 30 Hz – 27 kHz (7½ IPS, WR tape); 30 Hz – 25 kHz (3¾ IPS)
• Wow & flutter: <0.03% WRMS (7½ IPS); <0.04% WRMS (3¾ IPS)
• Signal-to-noise ratio: better than 62 dB (DIN 45500)
• THD: <0.5% (1 kHz, 0 VU, 7½ IPS)
• Erase ratio: better than 70 dB (1 kHz)
• Crosstalk: better than 40 dB (1 kHz)
• Channel separation: better than 55 dB (1 kHz)
• Bias frequency: 100 kHz
• Pitch control: greater than ±6%
• Real-time counter: up to 99 min 59 sec
• Rewind speed: 120 seconds for 1800 ft tape
• Inputs: Line 70 mV (100 kΩ), DIN 2 mV, Mic 0.25 mV
• Outputs: Line 0.775V (20 kΩ), DIN 0.3V, Headphones 100 mV (8 Ω)
• Remote: compatible with Akai RC-18.70R remote control
• Power: Multi-voltage 110/120/220/240V, 50/60Hz, 70W
• Dimensions: 440 × 483 × 256 mm
• Weight: approx. 21 kg (46 lbs)
• Year introduced: 1979

Shipping

Securely packed for safe delivery worldwide. Local pickup also welcome. Quoted international shipping rate is to Australia, the farthest destination from my US location — please inquire for a quote to your specific international address. This is a heavy, delicate, and valuable machine and will be fully insured.