AKAI GXC-740D

Commentary

Stereo cassette deck with 3 heads.

A 3-head configuration is used for the head part.
The 3-head system, which can be used exclusively for recording and reproducing heads, can be designed to fully display the characteristics required for each head, enabling recording and reproduction taking full advantage of the performance of tape.

Newly developed REC/PB combination GX head is used for the head.
This head uses an ultra-narrow gap of 4 μ for the recording head gap and 1 μ for the reproducing head gap. This improves high-frequency linearity, which is a weak point of the cassette, and provides frequency characteristics that extend flatly from low to high frequencies. The GX head also maintains excellent initial characteristics due to its wear-resistance characteristic.
The REC/PB Combination GX Head has 2 gaps for the pad of the cassette half which is made for 1 gap. Moreover, the surface shape has been devised so that the tape touch can be sufficiently taken. The parallelism of the recording gap and the reproduction gap and the direction deviation between channels are suppressed to the extent that they have almost no effect by using the ultra-precision processing technology, and the azimuth loss and phase deviation are suppressed.
In addition, although the recording / reproducing head is adjacent to the recording / reproducing head at 4.5 mm, a special shielding method is adopted to reduce the effect of magnetic flux leakage (field-through) during simultaneous recording and tape monitoring. In addition, the contour effect, in which the low-frequency range fluctuates during playback, is dealt with by processing the head tip.
The time difference during simultaneous recording and tape monitoring is limited to 0.1 second.

Closed-loop double capstan system is adopted for the mechanism.
In this system, two pairs of pinch rollers and a capstan shaft cut off the tape feed and take-up sides to keep the tension in the loop constant at all times, prevent the tension from changing due to the tape winding diameter, and keep the touch of the tape to the head stable.
For parts that make up the running diameter, such as capstan shafts, belts, flywheels and pinch rollers, attention has been paid to improve dimensional accuracy and eliminate machining errors, including 3 mm φ capstan shafts with a mirror polished finish with a roundness error of 0.1 μ.

The capstan motor uses a small-size CPG built-in AC servo motor, which has been used in AKAI's open reel decks, for use in cassettes. The CPG built-in AC motor has a large rotational torque and accurately controls the rotation with the help of a servo amplifier. The CPG built-in AC motor has a large AC voltage detected by 40 gears inscribed on the fixed and rotating parts, and a frequency generator is built into the motor. This minimizes runout in the detection part and ensures smooth rotation.

A double independent drive system has been adopted in which the capstan and reel stand are separately driven by a dedicated rubber belt, so that no unnecessary burden is imposed on the rotation of the capstan, and stable tape travel is achieved.

Adopts a direct function change mechanism by adoption of a plunger.

Adopts a lock type pose mechanism.

A display lamp using LED is mounted.

Equipped with a VU meter and a peak level indicator that responds at + 7 dB.

Equipped with Dolby B NR as a noise reduction system.

It is equipped with ADR system.
In this method, the equalizer characteristics are automatically adjusted according to the sound volume and frequency band so that the high-frequency signal does not exceed the saturation level of the tape and over-recording is performed in accordance with the recording condition of actual use. This expands the high-frequency recording limit and enables recording taking advantage of the dynamic range of the tape.
You can play the ADR system can be played on any cassette deck.

The line and microphone can be mixed.

Equipped with a 3-position tape selector that also supports Ferrichrome tapes.

It is equipped with an MPX filter switch to improve the high-frequency characteristics in normal recording.

Equipped with a REC calibration volume that can adjust the level of each tape.

A housing lamp is mounted on the top of the cassette holder, and a reflector is used to illuminate the tape monitoring window of the cassette half from the rear so that the condition of the tape can be checked.


Equipped with a linear motion mechanism, the head, which moves up and down frequently, is moved in a straight line by the function of the linear shaft and bearing together with the block, eliminating the rattling of the front, back, left and right.
This improves the reliability of the mechanism and enables more faithful recording and playback.

There was a wood case as an option sold separately.

Model Rating

Type	Stereo cassette deck
Track system	4-track 2-channel stereo system
Tape speed	4.75cm/s
Wow and flutter	0.07%WRMS
Frequency characteristic	30 Hz ~ 18 kHz ± 3 dB (When Ferrichrome Tape Is Used) 30 Hz ~ 16 kHz ± 3 dB (When Chrome Tape Is Used) 30 Hz ~ 15 kHz ± 3 dB (When Using Low-Noise Tape)
Distortion factor	1.0% (1 kHz, 0 VU)
Signal-to-noise ratio	54dB When Dolby NR is used : 6 db improvement (1 khz), 10 db improvement (5 khz or more)
Bias frequency	100kHz
Heads	Recording : GX Combination Head x1 Erase Head x1
Motor	One AC servo outer rotor motor with built-in CPG
Fast forward and rewind time	70 seconds or less (C-60 tape)
Input level	Mic : 0.3mV/-69dB/600 Ω ~ 10k Ω Line : 70mV/-21dB/100k Ω
Output level	Line : 0.775 V (at 0 VU) / 20k Ω or more Headphone : 50mV/8 Ω
Pwer	100 VAC, 50Hz/60Hz
Power consumption	31W
External dimensions	Width 440x Height 142x Depth 306 mm
Weight	10.5kg
Attachment	Connection code x2 One small screwdriver
Sold Separately	Wood Case CB-700 (¥ 7,000)