Technics RS-715U
¥ 129,000 (around the early 1970 s)
¥ 154,000 (around 1974)
Commentary
3-motor tape deck adopting HPF head.
The head section consists of four heads, including a head for reverse playback. An HPF head is used for each of the recording head, reproducing head, and reverse playback head.
The HPF head has expanded its frequency characteristics by using a hot-pressed ferrite core with high permeability and excellent abrasion resistance. In addition, the bias current is reduced to about 1/2 at the oscillation frequency of 100 to 200 kHz, and abrasion resistance is more than 10 times that of metal materials.
The RS 715 u has a gap of 2 microns for playback and 10 microns for recording, and a hyperbolic shape with less contour effect.
The mechanism uses a 3-motor system, and the operation is designed to be switched by an electromagnetic plunger and relay.
The capstan motor uses a hysteresis synchronous type with high torque, and the torque motor uses an induction type. Each of these motors is directly connected to the reel stand. The feeding side and the take-up side with different rotational directions are designed separately to improve tape running stability.
A spherical thrust bearing is used for the bearing to reduce vibration and noise and improve wow and flutter characteristics.
The RS 715 u is equipped with a function of reciprocating playback.
Automatic reversal uses a foil sensing method that detects the reversal signal by attaching a sensing foil to the folded part of the tape. In addition, the delay device works at the time of reversal, and the pinch roller waits until the operation in the reverse direction is stabilized, so there is no fear of making an unpleasant sound or damaging the tape.
The electrical circuit has an orthodox structure in which the recording system and the reproduction system are independent, and silicon transistors are used for all circuits.
A carefully selected low-noise transistor (2SC644F) is used in the first stage to ensure a wide dynamic range by supplying sufficient supply voltage.
It is equipped with independent amplifiers for VU meters and headphones, the line output is provided by an emitter follower, and the bias oscillation circuit is push-pull.
The microphone input and line input are equipped with independent level controls to enable mixing recording.
The impedance of the microphone terminal can be switched between two levels.
Equipped with a recording selection switch, it is possible to perform monaural recording for each track and to perform follow-up recording by switching to recording while the tape is running during playback.
Since the erasing head and recording head of this switch are turned ON / OFF, it can be turned OFF when it is not necessary to prevent the influence of bias current and external signal.
Equipped with an automatic reversing selection switch, one way stop, one round trip stop, and continuous round trip can be selected during playback.
When the image is reversed in the recording state, the image is automatically regenerating condition.
The power supply frequency can be switched between 50 Hz and 60 Hz using the driver from the rear.
By turning the selector shaft with a screwdriver, the belt can be changed and the phase advance capacitor can be changed simultaneously.
Equipped with sound-on-sound function.
Equipped with a tape select switch.
This switch controls the bias current so that the bias current is approximately 15% higher on the SG side.
The tension arm on the delivery side is a lock type that can be locked when the tape is attached. The lock is automatically released when the tape is run in the locked state.
In addition, the tension arm on the winding side also serves as a shut-off switch and automatically returns to the stopped state when the tape is finished.
Built-in reel clamper is adopted. When tape and reel are put on the reel stand and the clamper is pulled and turned, the reel is held firmly.
A large VU meter is used. When the meter is turned on, the dial is illuminated and a red light is turned on when recording.
The line output becomes 0.5 v at the position of 0 vu.
Equipped with a connector compatible with the optional remote control switch (RP-9715). When connected to the RP-9715, you can record, play, invert, and stop from a remote location.
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Model Rating
| Type | 3-Motor 2-Speed Stereo Tape Deck | ||||
| Recording bias system | AC-biased, 180 kHz | ||||
| Erasing method | AC erasing method | ||||
| Track system | 4-track 2-channel stereo | ||||
| Tape speed | 19cm/s, 9.5cm/s | ||||
| Head Used | Recording : HPFx1 Play : HPFx1 Reverse Playback : HPFx1 Erase : 1 ferrite |
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| Motor used | For Capstan : Hysteresis Synchronous Motor x1 For Reel : 2 induction motors |
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| Frequency characteristic | 19cm/s : 30 Hz to 22 kHz (35 Hz to 20 kHz ± 3 dB) 9.5cm/s : 40 Hz to 15 kHz ± 3 dB |
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| Wow flutter | 19cm/s : not more than 0.10% | ||||
| Signal-to-noise ratio | 50 dB or more | ||||
| Input |
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| Output |
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| DIN connector | REC/PB(EIAJ) | ||||
| Headphone | 8 Ω, 0.25 mW variable | ||||
| Semiconductor used |
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| Pwer | 100 VAC, 50Hz/60Hz | ||||
| Power consumption | Approx. 110W | ||||
| External dimensions | Width 431x Height 523x Depth 228 mm | ||||
| Weight | Approx. 24 kg | ||||