Akai 4000D (1970–1973)

Name: Akai 4000D
Brand: Akai

A Japanese-built reel-to-reel tape recorder from the early 1970s with a 3-head system and GX head technology

Overview

The Akai 4000D is a reel-to-reel tape recorder made in Japan by Akai Electric Co., Ltd. between 1970 and 1973. It was the basic model in the 4000 series. It records stereo and monaural on a 4-track 2-channel system. The 3-head setup has separate record, playback, and erase heads, so you can monitor the tape while you record. Tape speeds are 19 cm/s and 9.5 cm/s, with NAB equalization. The head gap is 1 μm, achieved through ultra-precision processing.

Specifications

Product type	Reel-to-reel tape recorder
Production years	1970 - 1973
Manufacturer	Akai Electric Co., Ltd.
Made in	Japan
Color	Silver / Black
Track system	4-track 2-channel stereo / monaural system
Tape speed	19cm/s, 9.5cm/s (± 2%)
Wow and flutter	0.08% RMS or less (19cm/s)
Frequency characteristic	30 Hz ~ 24 kHz ± 3 dB (19cm/s), 30 Hz ~ 16 kHz ± 3 dB (9.5cm/s)
Distortion factor	1.0% at 19cm/s, 1 kHz, 0 VU
Signal-to-noise ratio (S/N)	60dB (JIS)
Crosstalk	40dB
Erasure rate	70 dB or more
Recording bias frequency	100kHz
Heads	3 heads (record, play, erase) — Recording: GX head / Playing: GX head / Erasing: erase heads
Motor	One 4-pole induction motor
Fast forward / rewind time	120/150 seconds (60Hz/50Hz, 370m tape)
Recording time	2-hour stereo recording (9.5cm/s, 370m tape used)
Input - Microphone	0.25 mV / Impedance 600 Ω
Input - Line	70mV/100k Ω or more
Input - DIN	2mV/10k Ω
Output - Line	0 ~ 775 mV (maximum, 0 VU) / Load impedance 50k Ω or more
Output - DIN	0.3 V (max., 0 VU)
Output - Headphone	0 ~ 100mV/8 Ω (maximum, 0 VU)
Semiconductor used	Transistor : 11 / Diode : 4 pcs / Integrated circuit Linear ICs : 4 units
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	36W
External dimensions	Width 440x Height 315x Depth 230 mm
Weight	13.2kg
Original price	¥69,800 (around 1978)
Attachment	Model 17 (No. 7) Empty Reel x1, Connection code x2
Sold Separately	Dust Cover DC-4000 (¥5,000)

Design

The Akai 4000D uses GX heads for both recording and playback. They are made from a low-noise crystal ferrite material developed through Akai's own magnetic technology. Compared to Permalloy or Sendust heads, they offer better dynamic response, better electromagnetic conversion efficiency, and more resistance to wear and dust buildup. The 3 independent heads allow real-time monitoring during recording, and the 1 μm gap comes from ultra-precision machining. A single 4-pole induction motor drives the transport, paired with a large flywheel for stable tape movement. Operation is by a 2-lever mechanism. A tape selector optimizes performance for different tape types (e.g., Scotch #211 or #1500). The line and microphone input circuits are independent, which supports mixing. A VU meter linked to a monitor switch shows input and output levels. The unit also has a 4-digit index counter, temporary stop and auto-stop mechanisms, and adjustable output levels for line and headphone outputs.

Context

The Akai 4000D was the base model in the 4000 series lineup. It offered core professional-grade features in a consumer-accessible package, and it was the entry point into Akai's GX-head-equipped reel-to-reel range. The emphasis was on reliability and high-fidelity performance for home recording enthusiasts.