SONY TC-K55

Commentary

This metal tape-compatible cassette deck was developed not only for basic performance but also for overall perfection in sound quality and operability.

A microcomputer has been installed in the operation section of the cassette deck. Since the timing of each operation of the mechanism section is controlled in time series, the operation is completely stopped before moving to the next operation. Therefore, no excessive force is applied to the tape in the cassette half, preventing the tape from stretching. Furthermore, the complicated transmission mechanism is simplified due to the electromagnetic solenoid drive, and reliability is improved.
In these operations, first, the motor rotates in accordance with each operation mode, and the Hall element detects pulses corresponding to the number of rotations of the magnet (rotor). This is counted by the microcomputer, processed logically and digitally, and the mechanism is operated by driving the trigger plunger.
A 4-bit 42-pin LSI (CPU) is used for this operation control unit, making it compact with a discrete type combined with transistors, and realizing a highly reliable and responsive logic circuit.

It is a direct change operation in which you can move directly to the next operation without pressing the stop button during operation.
In addition, the Send button, Record button, and Pause button lights up when each function is active, so you can easily check their operation.

The head uses an S & F head that combines the high frequency characteristics of ferrite with the high saturation magnetic flux density of Sendust alloy.
The erasing head uses a magnetic focus 4-Gap erasing head with a magnetic focusing structure that uses a magnetic lens to apply strong magnetic flux to the tape.

BSL (brush and slot-less) motor is used.
This motor eliminates the cogging by the slot (groove) for forming the magnetic pole in order to solve the torque unevenness problem of the conventional DC motor from the structure, and achieves quiet and smooth rotation by the simple structure with no brush.

In the mechanism section, a BSL green motor for constant speed running (FWD) and a high-torque motor for quick winding (FF/REW) are exclusively used, and the structure is simple without complicated transmission structure. This improves reliability, reduces rotational loss, and achieves stable running by combining with frequency servo system.
To further improve the reliability of this 2-motor mechanism, each operation is driven by an electromagnetic solenoid, and the lock mechanism of the operation button and transmission mechanism such as idler are simplified to improve the reliability.

As a noise reduction system, Dolby NR is installed.
The Dolby IC has a built-in line amplifier and recording equalizer amplifier. The number of elements is equivalent to 160. Thus, complicated circuit routing can be avoided and sound quality is improved. In addition, since the recording / re-switching switch can be omitted, the reliability of the amplifier section is improved.

In order to eliminate uneven torque on the reel base, which causes disturbances in tape running, we have adopted a non-contact magnet clutch that transmits torque to the reel base by magnetic force. This eliminates mechanical friction and ensures stable torque while improving the reliability of the mechanism.

In order to prevent malfunction of the Dolby NR circuit with 19 kHz pilot signal during FM air check, an MPX filter switch is mounted to cut the pilot signal.

The amplifier section uses ± 2 power supply system, and the S & F head and amplifier section are directly coupled to achieve low distortion and excellent high-frequency characteristics.

Equipped with Rec Mute function with auto space, it cuts the recording source, creates optimum space between songs, and automatically switches to a paused state.
If you want to make a blank for less than 4 seconds, press the pause button to release it. If you want to make a blank for more than 4 seconds, press and hold the button to make a blank for only that time, and release your finger to make a temporary stop.

Equipped with autoplay / memory play function.

It is equipped with a follow-up recording function. When you want to play a part of the tape and record after that, you can press the feed (FWD) button and the record (REC) button at the same time to immediately enter the recording state.

The VU meter is equipped with a peak level indicator that displays in five levels (-8/-3/0 / + 2 / + 4 dB) to respond to a pulsed signal that cannot be indicated by the VU meter. In particular, + 4 dB corresponds to + 8 VU of the VU meter, so you can set the recording level taking advantage of the saturation level of the metal tape.

It is equipped with twin VU meter that follows in proportion to volume feeling with little indication error.

Equipped with a microphone / line input change-over switch that greatly improves the SN ratio at line input.

Equipped with a 4-step tape selector with independent bias / equalizer.
The equalizer has four levels : Type-I (normal), Type-II (for CrO2 and JHF cassettes), Type-III (for Fe-Cr and DUAD cassettes), and Type-IV (metal). The bias has four levels : norma (I/III), low / high (II), and metal (IV).

Built-in see-through lamp that can check the remaining amount of the tape.

Uses an auto shut-off mechanism that does not damage the mechanism or tape.

By using the timer (sold separately), you can record a continuous absence or play an alarm clock.

Remote control unit sold separately allows operation from a remote location.

Model Rating

Type	Stereo cassette deck
Track format	4-track 2-channel
Heads	Recording : S & F Erasing : F & F
Motor	BSL Green Motor High torque motor
Servo system	Hall element detection frequency servo
Wa flutter	0.04%WRMS
Frequency characteristic (Metal Tape)	20 Hz to 19 kHz 30 Hz to 13 kHz ± 3 db (at 0 VU recording)
Signal-to-noise ratio	59 dB (Dolby off, Peak Level, DUAD cassette)
Distortion factor	1.0% (DUAD Cassette)
Input terminal	Mic : 0.25 mv (-70dB) / Suitable for low-impedance microphones Line : 77.5 mV (-20dB) / 50k Ω
Output terminal	Line : 0.435V/50k Ω Headphone : -28dB/8 ohm load
Pwer	100 VAC, 50Hz/60Hz
Power consumption	16W
External dimensions	Width 430x Height 130x Depth 290 mm
Weight	5.2kg
Attachment	Stereo connection code 2 pcs Head cleaning rod
Sold Separately	Wired Remote Controller RM-50 (¥ 6,000)