AKAI GX-285D
¥ 159,000 (around 1973?)
Commentary
A high-grade stereo tape deck GX-280D with a Dolby NR system.
The head uses Akai's characteristic Glass & Single Crystal GX head (GX head).
A unique single crystal is used for the core material of the GX head, and the whole is wrapped in ultra-hard glass.
The single crystal is made of a single crystal and has excellent electromagnetic conversion efficiency and high-frequency characteristics because there is no gap inside the core compared with permalloy and general ferrite. In addition, S/N has been improved compared with permalloy and general ferrite by reducing noise.
In addition, since it has excellent abrasion resistance, it can be precisely processed into a narrow gap and the gap depth can be made shallow. This realizes the best head touch and sharp focus magnetic field (focus field).
These features make it possible to reduce the high-frequency loss due to the excellent magnetic characteristics, reduce the compensation amount of the equalizer on the recording amplifier side to compensate for the loss of the head, and enable high-level recording by the increase of dynamic margin especially during recording.
Equipped with a Dolby system to reduce tape noise.
The principle is that when recording on tape, when the input signal is only in a range lower than a certain level, or when the overall volume is small and noise is conspicuous, the volume is automatically increased with emphasis on the high range and the overall volume difference is compressed.
Then, during playback, it automatically reduces by the augmented amount to return to the original balance, which reduces noise by the restored amount.
A direct capstan drive system has been adopted for the tape running system.
The outer rotor motor, control winding and speed detection gear are integrated into an integrated structure, and an AC servo control motor is mounted, which is designed to detect motor speed purely electrically and compensate for changes in rotational speed by electromagnetic brake using servo circuit and frequency oscillator. Thus, constant rotational speed is maintained without being affected by fluctuations in power supply voltage or power supply frequency.
In addition, two 6-pole eddy current outer rotor motors are used for the reel drive, providing excellent driving characteristics.
It is equipped with a tape switching switch. When using a low-noise tape, it can be set to S. R. T to show its characteristics.
Equipped with a monitor switch, you can compare the sound before and after recording simply by switching the monitor switch alternately between Source and Tape.
Line recording level control and microphone recording level control are installed independently.
The sound-on-Sound system allows you to enjoy multiple performances by one person or overlapping recordings, the Sound-with-Sound system is convenient for language and instrument training, and the Line-microphone input mixing recording is available.
Equipped with a direct function change system, you can record, play back, fast forward, rewind, and stop all with one touch operation. You do not need to press the stop button every time you switch.
Equipped with an automatic stop mechanism that automatically stops the reel rotation at the end of the tape.
It also comes with a convenient automatic shut-off feature that automatically shuts off the entire unit.
Equipped with a 4-digit index counter.
Equipped with a pause button that allows you to temporarily stop the tape running during recording and playback.
Model Rating
| Type | Stereo tape deck |
| Track system | 4-track 2-channel stereo / monaural system |
| Maximum use reel | No. 7 |
| Tape Speed | 19cm/s, 9.5cm/s |
| Wow and flutter | 0.08% RMS or less (19cm/s) 0.12% RMS or less (9.5cm/s) |
| Recording (playback) compensation characteristics | NAB characteristics |
| Frequency characteristic | 30 Hz to 24,000 Hz ± 3 dB (19cm/s) 30 Hz to 19,000 Hz ± 3 dB (9.5cm/s) |
| Distortion factor | 1.5% or less at 1000 Hz, 0 VU |
| S/N | Normal : 50 dB or more Dolby : 58 dB or more |
| Erasure rate | 70 dB or more |
| Crosstalk | Mono : 70 dB or higher Stereo : 50 dB or more |
| Recording bias frequency | 100kHz |
| Heads | 4-track recording GX head 4-track regenerative GX head Erasing head |
| Motor | 2-speed servo control outer rotor motor (1 for Direct Capstan Drive) 6 Pole Eddy Current Outer Rotor Motor (one each for feed and take-up reel) |
| Fast forward / rewind time | 60/75 seconds (370m Tape Specification), 60Hz/50Hz |
| Recording time | 2-hour stereo recording (9.5cm/s, 370m tape specification) |
| Output jack | Line (2 systems) : 1.23 V (0 VU) / 100 Ω (optimum load impedance : 20k Ω or more) Headphone (1 system) : 30 mv ~ 40mV/8 Ω |
| Input jack | Microphone (2 systems) : 0.8mV/10k Ω Line (2 systems) : 150mV/150k Ω |
| DIN jack | 0.4V/50mV (High) 5 mv (Low) / 68k Ω |
| Semiconductor used | Transistor : 39 Diode : 32 pcs Linear ICs : 2 units |
| Power supply voltage | 100 VAC ~ 240 V, 50Hz/60Hz |
| Power consumption | 33W ~ 130W |
| External dimensions | Width 435x Height 460x Depth 260 mm |
| Weight | 21kg |
| Attachment | 1 x 7 Empty Reel Connection code x2 One sensing tape Two spare fuses |