Pioneer CT-970
¥ 115,000 (released in 1980)
Commentary
Stereo cassette deck equipped with ribbon sendust head and Auto BLE system.
The head part uses Ribbon Sendust Combination 3 heads.
The Ribbon Sendust Head uses Pioneer's unique technology to make a thin strip of Sendust to 50 microns and has a laminated structure of 11 sheets. This thin fasciation suppresses the generation of eddy currents and prevents the degradation of high-frequency characteristics. Moreover, the bias efficiency is improved to about twice that of the conventional Sendust Head, and excellent performances are obtained.
In addition, in order to obtain excellent channel separation, the ribbon sendust head takes into account the shielding effect against leakage magnetic field. For the core spacer where both left and right channels are adjacent, non-magnetic high-conductive material with high electrostatic shielding effect and permalloy shield plate with excellent magnetic shielding effect are adopted. The sound quality is enhanced by double shield combining the electrostatic shield effective for high frequency and the magnetic shield for low frequency. In addition, the structure between both channels is provided with an appropriate distribution angle, and the channel separation is further improved by high-precision core processing technology and deep gap design.
The recording and reproducing heads are a combination type in which the optimum gap can be selected by comprehensively analyzing the frequency characteristics, distortion, and sensitivity of each head. By setting the gap width to 0.8 micron for the reproducing head and 2.5 micron for the recording head, the performance of each head is brought out, and sound quality degradation due to azimuth shift and fluctuation of the tape touch is also suppressed.
It is equipped with an Auto BLE (Auto Bias Level Equalizer) system to bring out the performance of the tape.
In the AutoBLE system, a 4-bit microprocessor automatically searches for the optimum recording bias, recording level (tape sensitivity), and recording equalizer for each tape and adjusts it to ensure the best recording.
For tuning, the AutoBLE unit sends a command to the mechanism control circuit to enter the recording mode. Then, the 1 kHz oscillation signal is selected and supplied to the recording head via the recording amplifier. At the same time, the recording bias is also supplied to the recording head with the 1 kHz oscillation signal superimposed on the 1 kHz oscillation signal via the variable bias circuit. The recorded test signal is taken out by the reproducing head and supplied to the rectifying circuit of the AutoBLE unit to create a loop for recording and playback.
The automatic adjustment starts with the setting of the bias. In this method, the bias current is varied in 16 steps while recording a test signal of 1 kHz, and the optimum peak bias amount is detected with a high accuracy of ± 0.5 dB from the reproduced level. The reproduced signal supplied to the rectifying circuit of the Auto BLE unit is converted to a DC voltage, which is then converted into a digital value to determine the maximum reproduced level of the microprocessor.
When the bias amount is set, adjustment of the optimum recording level is started. At this time, the test signal is 1 kHz. The recording current is changed in 16 steps, and the reproduction output level of both channels is set to the specified level of 0 dB.
When adjusting the recording equalizer, the microprocessor selects a test signal of 10 kHz and adjusts the compensation amount of the recording equalizer in 16 steps to create a Furatto.
During adjustment, the LED on the front panel blinks, and when adjustment is finished, it is automatically rewound to the start position and the recording standby state is set.
The mechanism uses a 2-motor closed-loop dual capstan system, with a quartz PLL DD motor for capstan drive and a coreless motor for reel drive.
In the closed-loop dual capstan system, the tape is sandwiched between two capstan and pinch rollers on both sides of the head, so that the tape tension is always kept constant and good head touch is obtained. This reduces the modulation noise caused by drop-out, level fluctuation, and tape vibration.
A centralized display board is used for the display section.
This centralized display board uses LEDs to indicate the level meter, 4-digit electronic counter, signal route, Auto BLE operation, tape type, Dolby NR system ON/OFF, etc.
The level meter is equipped with a fast-response 16-segment wide-range 2-color LED peak level meter with a display range of -30 to + 10 dB and an auto-reset peak hold function of approximately 2 seconds.
Equipped with a memory stop / play function.
Equipped with a timer standby mechanism, and by connecting a timer sold separately, it is possible to record absence and play an alarm clock.
Equipped with a Rec mute mechanism.
Equipped with a bias manual variable function.
The Dolby System is installed as a noise reduction system.
Equipped with a 3-position tape selector of Norml, CrO2, METAL.
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Model Rating
| Type | Cassette deck | ||
| Heads | Recording : Ribbon Sendust (Combination Type) Play : Ribbon Sendust (Combination Type) Erasing : special alloy heads |
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| Motor | For constant speed drive : Quartz PLL DD capstan motor Reel Drive : Coreless Motor |
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| Quick winding speed | Within 90 seconds (at C-60) | ||
| Uneven rotation | 0.023% or less (WRMS) | ||
| Frequency characteristic |
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| Signal-to-noise ratio | Dolby OFF : 60 dB or more Dolby ON : 70 dB or more (5 kHz or more) (3rd harmonic distortion rate 3%, audibility correction) |
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| Distortion factor | 1.2% or less (0 dB) | ||
| Operating part | Feather-touch type direct change | ||
| Input Sensitivity / Maximum Allowable Input / Impedance |
Mic : 0.3mV/100mV/10k Ω, 6 mm φ Jack (Applicable Microphone Impedance : 250 Ω ~ 30k Ω) Line : 60mV/15V/65k Ω, Pin Jack |
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| Output Reference Level / Maximum Level / Load impedance |
Line : 450mV/640mV/50k Ω, Pin Jack Headset : 70mV/90mV/8 Ω, 6 mm φ Stereo Jack |
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| Accessory function | Auto BLE system (automatic bias level equalizer adjustment) Dolby System (with LED Display) 2-color LED level meter with peak hold function (-30 to + 10 dB) 4-digit LED Tape Counter Volume for bias fine adjustment Memory Stop / Play Timer standby mechanism Automatic Tape Slack Remover / ATLC REC Mute Cassette rear light Power eject mechanism Tape running indicator Remaining tape indicator |
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| External dimensions | Width 420x Height 130x Depth 358 mm | ||
| Weight | 9.2kg |