Audio Database

RS-675U
Commentary

A cassette deck with a front control system.

RS-675U is a model that omits Dolby NR system from RS-676U.

The mechanism uses a 2-motor system that uses separate dedicated motors for the drive and reel of the capstan.
In the RS 675 u, a large flywheel directly connected to a capstan is driven by a high-precision flat belt. Combined with a new cassette holding mechanism, the wow flutter is as good as a direct drive.

The head uses an HPF head with excellent high-frequency characteristics.
The HPF head is made of ferrite processed at high temperature and high pressure. In particular, the gap part is finished with high precision in the order of microns, so that recording / reproducing is possible up to 25 kHz at 19cm/s. Moreover, the head surface is finished with mirror surface, and the shield plate and core holder are made of HPF material with the same hardness, so that the estimated life of 200,000 hours is realized.

You can can be done by removing the carver of the head part.

The front panel is equipped with mirrors and lighting to monitor tape movement.
In addition, if the tape is removed, the detection device by the microswitch will work and the mechanism will not operate.

An operation method using a micro switch is adopted.
The electromagnetic control circuit uses a non-contact switching system with SCR, transistor and diode to improve reliability, and four plungers are used for operation switching.
In addition, each button has a display lamp to check the operation status.

Equipped with photoelectric automatic stop device using CDs and pilot lamp, autostop is applied at the end of end of the tape and the mechanism is completely released.

Equipped with a memory play function.
If you turn on the memory switch, set the tape counter to 000, and rewind after running the tape, the tape stops at position 999 and starts playback automatically.

The new time constant of 70 μ S has been adopted for the equalizer for chrome tape, which improves the SN ratio by 4.5 db compared to the conventional time constant.

Equipped with a tape selector with built-in chrome tape automatic detection mechanism.
When a chrome tape with a sensing recess is set, the bias circuit and bias current are automatically switched for the chrome tape. The tape selector can also be manually operated.

The electrical circuit is designed with an emphasis on linearity. The transistor is a high-gain, low-noise type (2SC1327), and the emitter resistance is selected to be small for low noise.
In addition, an active filter is inserted in the output stage to cut the high-frequency band of 23 kHz or higher at 12dB/oct. to shut out noise sources such as via Threec.

Since the line and microphone input are completely separated and sent to the amplifier, the SN ratio and linearity during line recording are improved.
There is also a position tuner and an OFF position for quick input switching.

The left and right independent volumes are eliminated, and the main volume and balance volume are used to control the volume.
The output volume is semi-fixed and mounted on the rear panel.

A 2SC1407 push-pull system is used for the oscillation circuit and a stabilized power supply is used for the power supply to prevent the influence of voltage fluctuations.
This oscillator circuit is isolated by a shield case to minimize via Threec (-50dB or less).

Equipped with a level meter capable of peak display.
This meter has a built-in circuit for displaying peaks that rise quickly and recover slowly to accurately display the pulse input level.
The level display can be used separately from the normal level display depending on the switch.

Separately sold Dolby unit can be connected.

There was a wood case sold separately.

Model Rating
Type Cassette stereo tape deck
Heads Recording : HPF head
Erasing : double-field ferrite
Motor For capstan : Electronic speed control motor
For Reel : Machine Speed Control Motor
Tape speed 4.8cm/s
Recording track system 4-track 2-channel stereo
Recording bias frequency AC Bias, 90 kHz
Erasing method AC Erase
Signal-to-noise ratio 50 dB or more
Wow and flutter Not more than 0.10%
Frequency characteristic Normal : 20 Hz to 14 kHz
CrO2: 20 Hz to 15 kHz
Fast-forward rewind time 80 seconds (C-60 tape)
Maximum Input Sensitivity / Impedance Mic : 0.3 mV (-70dB) / 600 Ω ~ 20k Ω
Line in : 60 mv (-24dB) / 110k Ω
Tuner : 100 mV (-20dB) / 190k Ω
Output Level / Impedance Line out : 420 mv (-7.5 db) / 50k Ω or more
Headset : 45 mv (max) / 8 ohm
Semiconductor used Transistor : 44 pcs
Diode : 31 Units
Zener : 3
Rectifier : 3 pcs
Thyristors : 2
Power supply voltage 100 VAC, 50Hz/60Hz
Power consumption Approx. 25W
External dimensions Width 410x Height 140x Depth 360 mm
Weight Approx. 10.5 kg
Sold Separately Dolby NR Unit RP-969 (¥ 34,800)
Wood Case RP-9650 (¥ 3,000)