Audio Database

The

Nakamichi ZX-7
188,000yen(around the 1981 time)

Description
 
The stereo cassette deck which aimed at the threshold of the tapes performance by carrying a variegated calibration functionality.

The manual calibration organization is carried, it carries out in order of the azimuth of the recording head, a sound-recording regeneration level, and a bias using the adjustment mechanism arranged in the panel side, and the best condition united with the using tapes is acquired.
If a tapes selector is first set to ZX (metal), SX (CrO2), or EX (normal) and an azimuth switchpoint is pushed from the status of a sound-recording pause, a tapes will start and the sound-recording play of the 400Hz testing tone will be carried out.
Azimuth adjustment will be completed, if a regulating knob is turned so that the red indicator amplifier of a center may light up. Next, if an azimuth switchpoint is turned OFF, it will be automatically set to level adjustment mode. Looking at the indicated value of a level meter, a coordination volume is turned so that it may be set to 0dB also with a L/R channel.
If a bias coordination switchpoint is finally turned ON, the sound-recording play of the 15kHz (-20dB) testing tone will be carried out, the indicated value of a level meter carries out a 20dB sensitivity up, and like level adjustment, the bias coordination volume of L/R is turned so that a level meter may be set to 0dB.
If a reset button is pushed when all the coordinations are completed, a tapes will be automatically rewound by the start location and a coordination will complete it.

The mechanism control using a 4 bits of N-MOS microprocessor is adopted. Thereby, the relationship of operation information and the present operating state is considered for deck itself, and the more exact mechanism drive is enabled.
The operationality of soft touch operation and the stability are improving much more by this, and also the autoplay back, an easy queuing and following sound recording, etc. have also realized multi-functionalization.

Once it sets the channel balance of a recording level and right and left, after that, a master fader control switchpoint can perform the fade-in of a recording level, and a fadeout automatically.
The switchpoint serves as a two-step, and if it pushes once and detaches, if it keeps pushed, it can choose 2 speed for 2 seconds for 6 seconds.

In addition to Dolbey B NR, Dolbey C NR is carried and the sound-recording play simultaneous monitor is enabled by adopting a Dolby NR processor for exclusive use as a sound-recording system and each play system.
The mechanism control by a 4 bits of N-MOS microprocessor is adopted. It remains as it is, the deck itself considers the relationship of the ordered operation information and the present operating state, and the silence operation common to the deck of a Nakamichi constitutes the logical circuit of making a mechanism drive more correctly.

Moreover, the sound-recording saturation caused by the anti saturation network circuitry by the momentary Dainyuu power is suppressed.

The frequency-dispersion type double capstan scheme is adopted as a mechanism, and the tapes run which put the tapes and was stabilized with 2 sets of capstans and a pinch roller, and the uniform head touch are realized. Furthermore, in order to avoid an overlap of a flutter periodicity, two capstan diameters and a fly-wheel diameter were changed, and the reduction of rotation unevenness and the modification of a modulation noise are realized. Moreover, the ill effect by fine oscillation of the pressure ununiformity of a pad or pad spring material is prevented by equipping a tapes pad lifter.

In order to prevent making a flutter increase because the oscillation produced from a motor and other body of revolution gets across to a tapes,Compared with iron, the big aluminum alloy of the damping characteristics was used as a chassis material, by carrying out the outsert of the resin to this, the harmful fine oscillation was absorbed and the occurrence of the vibration is prevented.

According to the mechanism by a microprocessor control and a motor drive, operation sound has realized the small proper tape transport. If an operation button is pushed, a control motor will be operated by command of a microprocessor and a mechanism will be operated.
Not using the solenoid plunger, a merit, like there is little power consumption with few temperature rises with few tapeses and the damages to transport has been obtained by operation sound being small and a tapes being contacted soft with the scheme of driving a cam by a motor.
The PLL servo motor is adopted as a main motor, a rotational frequency variation is detected, the signal and phase of a reference-signal oscillator are compared, and it is controlling to the exact rotational frequency.

The original discrete 3 head scheme which special-purpose-ized three heads, a sound recording, a play, and an erasure, in the head part, respectively, and the structure top also made separate completely is adopted.
The P-8L type which adopted the lamination core of Krista Roy and prevented the loss by a 0.6-micron narrow gap is adopted as the head for a play. Moreover, the R-8L type of a 3.5-micron gap with the lamination core of Krista Roy is adopted as the recording head like the reproducing head. And the double gap type E-8L type which uses a sendust core at a ferrite core and a leading end is adopted as the erase head.

The double NF circuitry which applies the negative feed back to an electrolytic capacitor is adopted as a sound-recording equalizer circuitry, a playback-equalizer circuitry, and monitor amplifier, and the direct-current stabilization is attained at the same time it suppresses low distortion generated by a capacitor.
And sound-recording amplifier and the recording head were linked directly, and the tone-quality failure by a coupling capacitor is prevented. Furthermore, buffer amplifier is used for the sound-recording amplifier input side, and the improvement in a tone quality, such as IC-izing headphone amplifier, is aimed at.

The wide-range light emitting diode peak level meter of 50dB full scale which carries out digital display of the "-40dB-+10dB" to each right and left by 16 segments is carried.
This meter operates also as meter for a coordination at the time of level / bias calibration, and especially at the time of a bias coordination of 20dB, indicated value rises so that it may be easy to adjust.

The tape counter of the digital display by light emitting diode is carried.

The REC-Mute functionality is carried, and only while pushing the REC MUTE switchpoint, a non-signal sound recording can be performed.

The MPX filter is carried.

It is possible to use a general audio timer and to perform an absence sound recording, an alarm clock play, etc.

By an optional remote Control unit, tapes operation including a sound recording and a play can be operated by remote control.

Mechanism Microprocessor

Rating of a mode
Form Stereo cassette deck
Track format 4 track two-channel stereophonic system
Head Three heads (erasure x1, sound-recording x1, play x1)
Motor (for tape transports) For capstans :P LL servo motor
For reels: DC motor
Tape speed 4.8cm/s
Wow and flutter 0.04%or less WTD RMS
0.08%or less WTD Peak
Frequency characteristic (recording level -20dB) 20Hz-21kHz±3dB (ZX tapes)
20Hz-20kHz±3dB (SX, EXII tapes)
A comprehensive SN ratio (400Hz, 3% THD)
IHF A-Wtd rms)
Dolby B NR on: 66dB or more (70 microseconds, ZX tapes)
Dolby C NR on: 72dB or more (70 microseconds, ZX tapes)
A comprehensive distortion (400Hz, 0dB) 0.8% or less (ZX tapes)
1.0% or less (SX, EXII tapes)
Cancellation ratio 60dB or more (100Hz, 0dB)
Channel separation 37dB or more (1kHz, 0dB)
Crosstalk 60dB or more (1kHz, 0dB)
Bias frequency 105kHz
Input sensitivity/impedance Line: 50mV / 50kohm
An Output voltage/impedance
(400Hz, 0dB, output level maxima)
Line: 1V/2.2kohm
Headphone: 45mW/eight ohms
DC output only for a black-box series ±10V or 125mA maxima
Power source AC100V, 50Hz/60Hz
Power consumption A maximum of 40W
Dimensions Width 450x height 135x depth of 300mm
Weight About 9.5kg
Option Remote Control unit RM-200 (6,000yen)