Nakamichi ZX-9

Commentary

This is a cassette deck based on ZX-7 with improvements mainly on the mechanism and amplifier.

The mechanism uses a direct drive system using Nakamichi's unique super linear torque DD motor.
This motor has been developed focusing on flutter components that do not appear in figures on specifications, and is designed to eliminate uneven torque of the motor, which causes flutter.
A general motor rotates by the repulsive force of S and N of the magnetic field, and when the coil moves from the S pole to the N pole, the pole is switched and the torque becomes 0 instantaneously. In order to eliminate this 0 torque state, a general motor increases the number of driving coils to use two or three phases. However, when each phase turns on or off alternately, torque unevenness occurs.
To solve this problem, Nakamichi has come up with a method that creates three torques that vary sinusoidally with time and ensures that the resultant torque is always 1 in order to maintain constant torque at any moment. This method is used in the Super Linear Torque DD Motor.
In the Super Linear Torque DD motor, the current supplied to the coil is a 2-phase sinusoidal wave and the magnet is also a ring-shaped one with star-shaped magnetization to form a sinusoidal wave with the strength of the S pole and the N pole, thereby eliminating torque unevenness.
By adopting this motor, we have achieved excellent characteristics in the double-capstan system in which lowering the wow flutter is difficult.

As a noise reduction system, Dolby B type and C type are mounted.

Equipped with 3 types of tape selectors.
In addition, in order to maximize the performance of each tape, it is equipped with a bias adjustment mechanism independent of the left and right, a recording and playback level adjustment mechanism independent of the left and right, and an azimuth adjustment mechanism.

The mechanism uses a closed-loop dual capstan system to reduce modulation noise, and in the ZX-9, by changing the diameters of the two capstan, the inherent resonance frequencies of the capstan can be changed to avoid overlapping of flutter periods.
In addition, two types of materials, aluminum and plastic, are used for the entire structure to absorb vibrations before they are transmitted to the head and tape.

N-MOS4-bit microprocessor is used for the mechanism drive part.
In the ZX-9, the tape control mechanism is driven by a motor and a cam, and the operating position is transmitted to the microcomputer by attaching a potentiometer to the control cam of the mechanism. This method enables quieter and smoother operation than the method of driving the mechanism with a plunger.
In addition, because it can move quickly, it is possible to find the head accurately like a open-reel.

The head has a 3-head configuration with completely independent recording, playback, and erasing heads.

The recording equalizer circuit and the playback equalizer circuit are connected directly to the head without using a condenser, thereby eliminating sound quality degradation.
In addition, the recording equalizer circuit and monitor amplifier are double-NF circuits that apply NFB to an electrolytic capacitor, and the playback equalizer circuit is DC-operated to reduce distortion.

Equipped with an auto-playback function, you can stop at the position of the tape counter 0000 after fast forward or rewind and start playback automatically.

With the Easy Queuing function, you can listen to your recording at a reduced speed in fast-forward or rewind mode. You can select a queuing speed of 1/3 or 1/6. You can also stop in queuing mode and start playback from a pause state.

It is equipped with -up recording function, you can switch to recording mode while driving during playback.

The master fader control function allows you to fade in and fade out.
The switch has 2 stages, and you can choose 2 speeds of 6 seconds when you press it once and release it, and 2 seconds when you keep it pressed.

Equipped with a Rec Mute function, you can record without a signal as long as you press the switch.

Equipped with a 50 db full-scale wide-range LED peak level meter that digitally displays -40dB to + 10 db with 16 segments for L/R respectively.
This meter can also be used as an adjustment meter for level / bias calibration. Especially for bias calibration, the indicated value is increased by 20 dB to make it easier to adjust.

Equipped with a tape counter with a digital LED display that allows for positive counting up to 9999 and negative counting up to -999.

Equipped with a timer recording and playback mechanism. By using a separately sold timer together, you can record your absence or play an alarm clock.

It can be operated from a remote location by using the optional remote control unit.

Model Rating

Type	Cassette deck
Track format	4-track, 2-channel stereo system
Heads	3 (1 erase, 1 record, 1 play)
Motor	For Capstan : FG Servo, Brushless / Slotless / Coreless / Super Linear torque DD motor For Reel : DC Motor
Tape speed	4.8cm/s
Wow and flutter	0.022% or less WTD RMS 0.045% or less WTD Peak
Frequency characteristic	20 Hz ~ 21 kHz ± 3 dB (Recording Level -20dB, ZX Tape) 20 Hz to 20 kHz ± 3 dB (recording level -20dB, SX, EXII tape)
Overall S/N ratio (70 μ s, ZX Tape)	Dolby C Type NRon : 72 dB or more (400 Hz, 3% THD, IHF A-WTD, RMS) Dolby B Type NRon : 66 dB or more (400 Hz, 3% THD, IHF A-WTD, RMS)
Overall strain rate	0.8% or Less (400 Hz, 0 dB, ZX Tape) 1.0% or Less (400 Hz, 0 dB, SX, EXII Tape)
Erasure rate	60 dB or More (100 Hz, 0 dB)
Channel separation	37 dB or More (1 kHz, 0 dB)
Crosstalk	60 dB or More (1 kHz, 0 dB)
Bias frequency	105kHz
Input	Line : 50mV/70k Ω
Output	Line : 1 V (400 Hz, 0 dB, maximum output level) / 2.2k Ω Headset : 45 mW (400 Hz, 0 dB maximum output level) / 8 Ω
Dedicated Output for Black Box Series	DC ± 10 v, 125 mA max.
Pwer	100 VAC, 50Hz/60Hz
Power consumption	45W max.
External dimensions	Width 450x Height 135x Depth 300 mm
Weight	Approx. 9.5 kg
Sold Separately	Remote Control Unit RM-200 (¥ 6,000)