Nakamichi BX-125

Commentary

In addition to the simple configuration of 2-head single capstan, this is a basic cassette deck with minimal functions.
It is made in pursuit of the total balance for the sound as much as it is made simple.

In order to maintain an optimum balance between recording and playback characteristics, the effective gap width of the head is set at 1.2 microns, which is the playback limit of 20 kHz, and Sendust with a high saturation magnetic flux density of 10,000 gauss is used as the core material.
At Nakamichi, the core material is processed without stress at all, and a special treatment is applied after each process to prevent distortion. By carrying out strict and meticulous manufacturing control, the linearity of the gap is kept severe, and the regenerative capacity of 20 kHz is obtained.
It also uses a unique hyperbolic shape that minimizes the contour effect and reduces low-range waviness.

The erasing head uses a double-gap type that uses ferrite as a core material with excellent high-frequency characteristics.
High frequency loss is small, and even metal tapes with large coercive force and residual magnetic flux density have a high erasing rate.

The L/R printed circuit board pattern and circuit configuration of the amplifier section are designed to be perfectly symmetrical. Consideration is given to balancing part characteristics and aligning the signal shield line length in L/R.
In addition, over 30 items of adjustment are carried out in the manufacturing process for every unit to improve the total quality.

In the recording amplifier section, the compensation amount can be reduced because the characteristics of the head are good. As a result, the flat frequency characteristics are maintained with a sufficient margin.
In addition, a double NF circuit has been adopted to reduce the distortion factor and to improve the DC stability while suppressing the generation of the distortion by the capacitor by having NF loops with separate DC and AC components.
In addition, a high-speed low-noise operational amplifier is used in the amplifier stage to reduce distortion.

The playback amplifier section is equipped with a double NF circuit similar to the recording amplifier section to improve constant distortion and DC stability.

In the mechanism part, removal of "flutter" is the most important point in designing the transport mechanism.
In the single-capstan type of the BX-125, the rotational accuracy of the reel motor for winding is closely related to the flutter. Therefore, a high-performance motor is used and the pulleys are made of metal with high roundness to prevent flutter during power transmission.
In addition, by firmly fixing the cassette in the reference position, vibration caused by looseness is eliminated.

Nakamichi's own silent mechanism is adopted.
In this system, no plunger is used to drive the mechanism, and a dedicated motor controlled by a microprocessor drives the operation control cam of the head base and brake. All operations can be started quickly by simply lightly touching the operation button.
In particular, damage to the tape is suppressed by making it a 2-speed transmission type in which the head moves quickly until just before it touches the tape at the start of the Play operation and slows down when it touches the tape.

Equipped with a double-speed master fader control that allows you to fade in and fade out in two stages of 4 seconds or 2 seconds.

It is equipped with many functions such as auto-repeat function, Dolby B / C type NR system, wide-scale LED peak level meter, MPX filter, memory stop, timer rec / play function, L/R independent recording level control, output volume, 3-position tape selector, equalizer selector, headphone jack, one touch rec pause, etc.

Model Rating

Type	Stereo cassette deck
Heads	2 heads (1 erase, 1 read / write)
Motor	<Tape Transport> Capstan Drive : DC Servo Motor For Reel Drive : DC Motor <Mechanism> Cam Drive : DC Motor
Wow and flutter	0.06% or less WTD RMS ± 0.11% or less WTD Peak
Frequency characteristic	20 Hz to 20 kHz (recording level -20dB)
Overall S/N ratio (70 μ s, ZX Tape, 400 Hz, 3% THD IHF A-WTD RMS)	Dolby C Type NRon : 68 dB or more Dolby B Type NRon : 62 dB or more
Total Distortion Factor (400 Hz, 0 dB)	ZX, EXII tape : not more than 1.0% SX Tape : 1.2% or less
Input Sensitivity / Impedance	50mV/30k Ω
Output Level / Impedance (400 Hz, 0 dB, maximum output level)	Line : 0.5V/2.2k Ω Headphone : 2.2mV/8 Ω
Pwer	100 VAC, 50Hz/60Hz
Power consumption	Up to 17W
External dimensions	Width 430x Height 100x Depth 250 mm
Weight	Approx. 5 kg