The Akai GX-630D SS is a vintage 4-channel Quadraphonic reel-to-reel tape deck produced between 1976 and 1979. As the "SS" (Surround Sound) designation highlights, it was Akai's final and most sophisticated true quadraphonic consumer tape deck, making it a highly collectible piece of audio history today. 

Key Features & Specifications

• Indestructible Heads: Built with Akai's legendary Glass and X'tal (crystal) Ferrite (GX) heads. These heads resist physical wear almost entirely, retaining original factory audio clarity for decades. 
• 4-Channel / Quadraphonic Design: Features four discrete microphone inputs and dedicated monitoring controls to record and play true 4-channel surround sound audio. 
• Large Reel Capacity: Supports standard 7-inch and professional 10.5-inch large tape reels. 
• Robust 3-Motor Drive: Relies on a highly stable three-motor tape transport mechanism to drastically reduce wow and flutter.
• Dual Speeds: Operates at 3.75 ips (inches per second) for prolonged recording time and 7.5 ips for high-fidelity studio-quality sound.
• Pitch Control: Includes a built-in pitch modification knob allowing for a 5% adjustment in playback speed.