Audio Database

ZX-7
Commentary

Equipped with various calibration functions, this stereo cassette deck aims at the limit of tape performance.

It is equipped with a manual calibration mechanism. Using the adjustment mechanism arranged on the panel surface, the recording head azimuth, recording and playback level, and bias are performed in this order, so that the best condition can be obtained according to the tape used.
First, set the tape selector to ZX (metal), SX (CrO2) or EX (normal) and press the Azimuth switch from the recording pause state to start the tape and record and play the 400 Hz test tone.
The azimuth adjustment is completed by turning the adjustment knob so that the red indicator amplifier in the center lights up. Next, when the azimuth switch is turned off, it is automatically set to the level adjustment mode. While watching the indication on the level meter, turn the adjustment volume so that it is 0 dB for both the L and R channels.
Finally, when the bias adjustment switch is turned on, a test tone of 15 kHz (-20dB) is recorded and played back. The sensitivity of the level meter is increased by 20 dB. Similarly to the level adjustment, the L/R bias adjustment volume is turned so that the level meter reaches 0 dB.
When all adjustments are complete, press the Reset button to automatically rewind the tape back to the start position and the adjustment is complete.

The mechanism control by N-MOS4-bit microprocessor is adopted, and the silent operation common to the Nakamichi deck is left as it is, and the deck itself considers the relation between the commanded operation information and the current operation state, and constructs a logic circuit to drive the mechanism more accurately.
As a result, the operability and stability of the soft touch operation have been further improved. In addition, multifunctional functions such as auto playback, easy queuing and follow-up recording have been realized.

Once you set the recording level and left / right channel balance, you can use the master fader control switch to automatically fade in and fade out the recording level.
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.

In addition to the Dolby B NR, a Dolby C NR is also installed. By using a dedicated Dolby NR processor for both recording and playback, simultaneous monitoring of recording and playback is possible.
In the C-type, two noise reduction processors (high level stage and low level stage) receive 10 dB each, and a total noise reduction of up to 20 dB is achieved. In addition, a sliding band method is adopted in which the frequency at which the operation starts is variable according to the input level and frequency component, preventing bleeding phenomenon.
An anti-data network circuit reduces recording saturation caused by large instantaneous saturation.

The mechanism employs a frequency-distributed double capstan system. The tape is sandwiched between two sets of capstan and pinch rollers to achieve stable tape travel and uniform head touch. In addition, the diameters of the two capstan and of the two capstan and the flywheel are changed to reduce rotation unevenness and improve modulation noise. In addition, by installing a tape pad lifter, adverse effects due to uneven pad pressure and slight vibration of the pad spring material are prevented. flutter

In order to prevent the flutter from increasing due to the vibration generated by motors and other rotating bodies being transmitted to the tape, we use aluminum alloy, which has a larger damping property than steel, as the chassis material. Plastic is out-plated on this alloy to absorb harmful microvibrations and prevent resonance.

The microprocessor control and motor-driven mechanism realizes low sound at the time of operation and suitable tape drive. When the operation button is pressed, the microprocessor commands the control motor to operate the mechanism.
By driving the cam with a motor instead of using a solenoid plunger, we have obtained advantages such as low sound at the time of operation, less damage to tape and transport due to soft contact with tape, less temperature rise, and less power consumption.
The main motor uses a PLL servo motor that detects rotational speed fluctuations, compares the signal of the reference signal oscillator with the phase, and controls the rotational speed to an accurate value.

The head section is dedicated to each of the three recording, playback and erasing heads, and uses a unique discrete three head system that is completely separated from the structure.
The P-8L type is used for the playback head, which uses a laminated core made of quartz and a narrow gap of 0.6 microns to prevent losses. The R-8L type is used for the recording head, which uses a laminated core made of quartz and a gap of 3.5 microns. The E-8L type is used for the erasing head, which uses a ferrite core and a Sendust core at the tip.

The recording EQ circuit, playback EQ circuit and monitor amplifier use a double NF circuit that applies negative feedback to an electrolytic capacitor. This reduces distortion caused by the capacitor and stabilizes direct current.
The recording amplifier is directly connected to the recording head to prevent deterioration of sound quality caused by the coupling capacitor. In addition, a buffer amplifier is used for the input side of the recording amplifier, and the headphone amplifier is integrated into an IC to improve sound quality.

Equipped with a 50 dB full-scale wide-range LED peak level meter that digitally displays -40dB to + 10 dB with 16 segments each on the left and right.
This meter also functions as an adjustment meter for level / bias calibration, and the indicated value is increased by 20 dB increased by 20 dB so that adjustment is easy.

Equipped with a tape counter with digital display by LED.

It has a REC mute function so that you can record without a signal only while the REC MUTE switch is pressed.

Equipped with MPX filter.

You can use a general audio timer to record your absence or play an alarm clock.

Tape operations such as recording and playback can be remotely controlled by the separately sold remote control unit.

Model Rating
Type Stereo cassette deck
Track format 4-track 2-channel stereo system
Heads 3 heads (1 erase, 1 record, 1 play)
Motor (for tape drive) For capstan : PLL servo motor
For Reel : DC Motor
Tape speed 4.8cm/s
Wow and flutter 0.04% or less WTD RMS
0.08% or less WTD Peak
Frequency response (recording level -20dB) 20 Hz ~ 21 kHz ± 3 dB (ZX Tape)
20 Hz ~ 20 kHz ± 3 dB (SX, EXII tape)
Overall SN ratio (400 Hz, 3% THD
IHF A-Wtd rms)
Dolby B NRon : 66 dB or more (70 μ s, ZX Tape)
Dolby C NRon : 72 dB or more (70 μ s, ZX Tape)
Total Distortion Factor (400 Hz, 0 dB) 0.8% or Less (ZX Tape)
1.0% or Less (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 Sensitivity / Impedance Line : 50mV/50k Ω
Output Level / Impedance
(400 Hz, 0 dB, maximum output level)
Line : 1V/2.2k Ω
Headphone : 45mW/8 ohm
Dedicated DC output for black box series ± 10 V, 125 mA max.
Pwer 100 VAC, 50Hz/60Hz
Power consumption 40W max.
External dimensions Width 450x Height 135x Depth 300 mm
Weight Approx. 9.5 kg
Sold Separately Remote Control Unit RM-200 (¥ 6,000)