Nakamichi 550

Commentary

This is a cassette deck that can be used as a stationary deck in the room and is also suitable for live recording.

A magnetic focusing type recording and reproducing head is used for the recording and reproducing head.
Recording is not performed in the head gap as generally believed, but in the decay process of the bias magnetic flux. This range is called the critical zone, which is the effective gap of the recording head. With conventional heads, delicate recording cannot be performed because this critical zone is wide. Even with a physically 1.5 micron gap, the effective gap is more than 2 microns. This is caused by the deformation of the pole piece around the gap.
To solve this problem, Nakamichi started by reexamining the head manufacturing process and removed distortion by specially processing the tip of the pole piece. This is called a magnetic focusing head.
By this magnetic focusing method, the critical zone is ideally focused, and the high-frequency distortion is minimized.

The drive section employs a newly developed duty control DC-servo motor for the 550 to reduce loss, thereby realizing high efficiency and stable rotation with less current and less wow flutter.

Energy-saving design is emphasized, and 15 hours continuous recording is possible with standard (super) D Battery.
Alkaline dry batteries can record data continuously for about 45 hours.

Built-in DC/DC converter.
This maintains a constant output voltage even when the battery voltage changes from 7 v to 14 v. A 90% efficient converter with excellent conversion characteristics is used to stabilize stable performance.

The level meter uses a 45 dB full-range peak meter instead of the standard -20dB level meter.
This allows for both subtle sounds that are likely to be buried in noise and roaring sounds, as well as instantaneous input, and prevents distortion due to level adjustment errors.

Equipped with a tape utility indicator.
When you press the button, the peak meter on the left indicates the amount of tape remaining, which is indicated as a percentage regardless of the length of the tape, such as C-60 or C-90.

Battery voltage can be checked with one touch.
When the button is pressed, the peak meter on the right indicates the battery voltage.

It is equipped with a tape end alarm using LED, and the LED on the front panel lights when the end of the tape is near.
It is also equipped with a programming timer. By adjusting the knob of the timer, you can preset the time when the alarm lights up.

Equipped with 3-point microphone mixing function.
In addition to the stereo / microphone L/R, it is also equipped with a blend microphone input so that you can adjust the recording level and mix them.
It can be used in a variety of ways, such as picking up reverberation and background noise with a blend microphone to enhance the sense of presence, or adding narration.

Built-in microphone amplifier with dynamic range of 115 dB.
When it is inserted into My Kujac, the line input is cut and the amplifier operates.

It has a built-in headphone amplifier with volume.

Equipped with a 400Hz0dB test tone that can be used to adjust the level of Dolby NR.

Equipped with a peak limiter function.
It automatically operates in the case of an unpredictable and instantaneous large input, and compresses large input of 0 dB or more to about 1 / 7 and prevents generation of distortion.

Equipped with a tape selector switch.
The EX position corresponds to high-density low-noise tape (Nakamichi EX/EXII), and the SX position corresponds to CrO2 system (Nakamichi SX, etc.).
The time constant for playback is 70 μ s for SX and 120 μ s for EX.

Equipped with an output volume.

The power supply voltage is 12 v, and 8 dry batteries are used.
The external power supply comes with a cord that can be plugged into a cigarette lighter socket in a car and an AC pack that can be taken from a carjack or home AC power supply.
Because the battery life is long, unnecessary power transformers and rectifier circuits for outdoor use are eliminated from the body.

Equipped with an auto shut-off mechanism, all push buttons are automatically unlocked when the tape is finished.

Equipped with Dolby NR as a noise reduction system.

There was a carrying case as an optional item sold separately.
This carrying case has a soft body so that it fits easily to the body and is resistant to external shocks. In addition, the center of gravity is low because it is vertically long, and it is stable even when walking on the shoulder.

Model Rating

Type	Stereo cassette deck
Tape speed	4.8cm/s
Wow and flutter	0.08% or less Wrms
Frequency characteristic	40 Hz ~ 17 kHz ± 3 db (SX, EXII tape)
Overall S/N ratio	Dolby NR in : 65 dB or higher (CCITT, Wrms, 400 Hz, SX)
Overall strain rate	1.5% or Less (1 kHz, 0 dB)
Erasure rate	60 dB or More (1 kHz Saturation Level)
Channel separation	35 dB or More (1 kHz, 0 dB)
Crosstalk	60 dB or More (1 kHz, 0 dB)
Bias frequency	105kHz
Input	Mic : 0.2mV/600 Ω / -72dBm Blend Mic : 0.2mV/600 Ω Line : 70mV/150k Ω DIN : 25mV/47k Ω
Output	Line:580mV Headset : 100mW/8 Ω (1 kHz, 0 dB)
Pwer	12 VDC (Single Dry Cell x8, Car Battery, AC Pack)
External dimensions	Width 311x Height 89x Depth 350 mm
Weight	Approx. 5.1 kg (Excluding Battery)
Attachment	Automotive connection code AC Power Pack
Sold Separately	Carrying Case (¥ 12,000)