AKAI GX-400Dpro

Commentary

Professional tape deck with tape deck.

GX head is used for the head part.
The GX head uses Akai's unique single hard glass for the core material, and the whole structure is wrapped with super crystal. The single crystal is used for the core material, which is advantageous in terms of magnetic characteristics, has good electromagnetic conversion efficiency, and has excellent high-frequency characteristics. In addition, since the noise is reduced by an epoch-making method, an S/N ratio superior to that of Permalloy or general ferrite is realized. In addition, the single crystal does not wear like Permalloy even after a long period of use, and unlike general ferrite, the single crystal does not lose particles on the tape contact surface, and does not peel off or crack on the surface. Thus, excellent abrasion resistance is ensured.
In addition, the super hard glass that covers the core is excellent in abrasion resistance, and has a characteristic that it does not accept iron oxides like magnetic tape, dust and dirt.

The head section is equipped with a 2-track recording GX head, a 2-track playback GX head, a 4-track playback GX head, and a full-track erasing head.

The mechanism section employs a double-capstan drive mechanism using a newly designed AC servo motor.
The capstan drive motor uses an inner rotor 3-speed AC servo motor. In this motor, the voltage supplied to the stator winding is controlled by the pulse detected by the rotational speed detection coil, and a constant rotational speed is maintained at all times. As a result, accurate rotational speed and torque are obtained regardless of fluctuations in external load conditions.
In addition, tape speed deviation is reduced by using advanced electronic control circuit which is protected from unnecessary hum.

Two 6-pole eddy current inner rotor motors are used for the reel drive motor.

Equipped with Akai's own air dump type tension arm.
When the tension arm is lowered, it lowers with normal force, but only when tension is applied to the tape, the one way air damper works to prevent sudden large tension on the tape. However, the air damper does not work when the tape is raised slowly. Therefore, even when the operation button is pressed suddenly from the state where the tape is loose, there is no worry that the tape will be cut or wound into the flange.
In addition, the one way air dump / tension arm prevents lateral movement during rapid feed and rewinding, protecting the edge of the tape and allowing it to be wound neatly on the reel.

The system control consists of 8 relays, 4 plungers and a logic circuit for driving them, including the one for switching the signal of the amplifier section. In addition, all the plungers are noiseless so that no unpleasant shock sound is generated during operation.

A direct function change system has been adopted. Recording, playback, fast forward, rewind, and stop can all be operated with one touch. There is no need to press the stop button every time the operation is changed.

The amplifier section is composed of a high-grade circuit design including a constant voltage circuit and a first stage equalizer. Each amplifier uses a PNP-NPN type transistor direct-coupled circuit to reduce noise and increase dynamic margin.
The recording amplifier consists of a 3-stage direct-coupled circuit of NPN-PNP-NPN to achieve low noise. In addition, since the GX head with focus field bias is used, peaking is done by the CR circuit instead of the LC circuit. As a result, harmonic components are removed, resulting in a low distortion rate and improved square-wave characteristics.

The microphone amplifier has four independent circuits built in.
Each has sufficient gain and a dynamic margin of more than 55 dB, as well as a dedicated step-type volume for two channel mixing recording using four microphones.

Equipped with a tape selector switch, compensation characteristics can be switched to match the low-noise tape.
It uses a method that varies the amount of peaking during recording for low-noise tapes.

The recording amplifier section is equipped with Akai's own A. D. R system (Automatic Distortion Reduction System).
This automatic distortion reduction circuit was used in the Akai cassette deck and was newly developed for two tracks. In this A.D. R system, the distortion is eliminated by controlling the head current so that the high-frequency signal does not exceed the saturation level of the tape, in order to eliminate the distortion factor of the high-frequency signal and the accompanying mid-range and low-frequency beats by utilizing 100% of the dynamic range of the tape.
On the circuit, variable impedance characteristics between source and drain of FET are used.

You can use the pause switch to pause during recording and playback.
You can also use the Cue switch to check the playback sound during fast forward and rewind.

Equipped with an A.P. F (Automatic Program Finder) switch.
By using the sensing foil, you can automatically rewind from the playback mode and play from the rewind mode. This enables auto-repeat playback with auto-rewind and auto-play.

Model Rating

Type	Tape deck
Recording track system	2-track 2-channel stereo
Recycled track system	2-track 2-channel stereo 4-track 2-channel stereo
Maximum use reel	No. 10
Tape speed	38cm/s, 19cm/s, 9.5cm/s
Wow and flutter	0.035% RMS or Less (38cm/s)
Recording (playback) compensation characteristics	NAB characteristics
Frequency characteristic	38cm/s : 30 Hz to 27 kHz ± 3 dB (0 VU recording)
Velocity deviation	± 0.5%
Distortion factor	1% or less (1 kHz, 0 VU)
Signal-to-noise ratio	58 dB or more
Recording bias frequency	160 kHz ± 10 kHz
Crosstalk	50dB
Input Sensitivity / Impedance	Mic : 0.5mV/600 Ω ~ 10k Ω Line : 50mV/50k Ω Din : 10mV/30k Ω (Low), 250mV/60k Ω (High)
Output level	0.775V(0dB) Variable range : 0 to + 6 dB
Output impedance	100 Ω (Optimum Load Impedance 10k Ω or More)
Headphone out	Maximum 50mV/8 Ω
Heads	2-track recording GX head GX head for 2-track reproduction 4-track regenerative GX head Full track erase head
Microphone amplifier dynamic range	55dB
Fast forward / rewind time	120 seconds or less (when 740m tape is used)
Motor	For Capstan : 3-Speed AC Servo Motor For Reel : 2 x 6 Pole Eddy Current Inner Rotor Motors
Semiconductor used	Transistor : 64 FET : 2 Diode : 65 pcs
Pwer	100 VAC ~ 240 V, 50Hz/60Hz
Power consumption	160W maximum
External dimensions	Width 457x Height 589x Depth 258 mm
Weight	30.5kg
Attachment	Empty reel Reel hub adapter Connection code Sensing foil Spare fuse