Akai 4000D (1970–1973)
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. Marketed as a basic model in the 4000 series, it was designed for stereo and monaural recording using a 4-track 2-channel system. The unit features a 3-head configuration—separate record, playback, and erase heads—allowing for simultaneous monitoring during recording. It supports tape speeds of 19 cm/s and 9.5 cm/s, with NAB equalization and a 1 μm head gap 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, made with low-noise crystal ferrite material developed through Akai’s proprietary magnetic technology. These heads offer superior dynamic response, electromagnetic conversion efficiency, and resistance to wear and dust buildup compared to Permalloy or Sendust types. The transport employs a 3-head system with independent heads, enabling real-time monitoring during recording. A 1 μm head gap is achieved via ultra-precision machining. The drive system uses a single 4-pole induction motor paired with a large flywheel for stable tape movement. It features a 2-lever operation mechanism, tape selector for optimizing performance with different tape types (e.g., Scotch #211 or #1500), and independent line and microphone input circuits to support mixing. The unit includes a VU meter linked to a monitor switch for input/output level display, 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 developed as the base model in the 4000 series lineup, offering core professional-grade features in a consumer-accessible package. It served as an entry point into Akai’s GX-head-equipped reel-to-reel range, emphasizing reliability and high-fidelity performance for home recording enthusiasts.
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