Pioneer CT-A1
¥ 230,000 (around 1980)
Commentary
This is a stereo cassette deck that aims at the highest quality by using the Auto BLE system and the 3-head system that uses the world's first ribbon sendust head.
It uses a 3-head system with a recording / playback combination head using Ribbon Sendust, which was developed for the first time in the world, and an erasing head using a special alloy.
The ribbon Sendust head is manufactured by an ultra-rapid cooling method in which molten center dust is ejected from a nozzle under appropriate conditions and directly extended through a roll. By this method, Sendust, which is limited to 0.2 mm ~ 0.3 mm with the conventional technology, has been successfully reduced to a thin band of 50 μ m at a stroke. Moreover, by molding this ribbon Sendust into 11-sheet laminate structure and suppressing the generation of overcurrent, the degradation in the high-frequency range is remarkably improved and excellent high-frequency characteristics are realized.
In addition, this ribbon Sendust head has a high SN ratio and wide dynamic range design taking advantage of the high magnetic permeability of Sendust itself, and bias efficiency is about twice as high as that of conventional Sendust heads.
The gap width of the reproducing head is set to 0.8 μ m in order to achieve both high frequency characteristics and high sensitivity. We succeeded in forming a narrow gap without sacrificing sensitivity by taking advantage of the characteristics of ribbon sendust.
The recording head the recording head has a gap value of 2.5 μ to maximize the frequency characteristics and sensitivity during recording. By taking advantage of the high saturation magnetic flux density and high sensitivity, sound quality is improved.
The Ribbon Sendust Head fully considers the shielding effect against the leakage magnetic field, and uses a shield plate made of non-magnetic high conductive material with high electrostatic shielding effect and permalloy with excellent magnetic shielding effect as the core spacer where both the left and right channels are adjacent. The sound quality is improved by double shielding.
In addition, the channel has a structure with an appropriate distribution angle between both channels, and the channel separation is made excellent by high precision core processing technology and deep gap.
For the erasing head, we have developed a special alloy with high saturation magnetic flux density and excellent abrasion resistance. We use a semi-double gap structure for the front core. In addition, we combine it with a ferrite back core to realize a compact and high-performance erasing head.
In addition, the front core made of this special alloy is laminated with 21 sheets of 0.1 mm thin plate, so temperature rise due to eddy current loss is small, and high erasing performance of over 76 dB (1 kHz, metal tape) is obtained.
It uses a newly developed AutoBLE system (Automatic Bias Level Equalizer Tuning System) that automatically detects the recording bias, recording level, and recording equalizer on the tape used by the 6-bit arithmetic processing of the microprocessor and sets it with high precision.
When adjusting the recording bias, regardless of the position of the tape used, the amount of bias current at which the sensitivity of the tape is high and distortion is reduced is selected and set to the optimum value.
When adjusting the recording level (tape sensitivity), the recording level is changed so that the recording and playback levels are the same, and the optimum value is set so that the curve of the code is symmetrical in encoding even when the Dolby system is in operation.
Recording equalizer adjustment automatically detects the high-frequency characteristics of various types of tapes, and adjusts the recording equalizer to the optimum value so that all bands are flat.
The AutoBLE System has a built-in memory function that stores up to nine bias level and equalizer adjustment values, which can be recalled when necessary. It also detects tape selector mispositions and faulty tapes, and alerts you with an error message.
The AutoBLE unit uses a microprocessor (PD 4005) developed by Pioneer for 6-bit arithmetic processing to adjust the bias level equalizers and various associated controls.
In the process, when the AutoBLE key is pressed, the AutoBLE unit sends a command to the mechanism control circuit to enter the recording state. 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 after being 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 recording / playback loop.
The automatic adjustment starts with setting the bias. The bias current is varied in 64 steps while recording a test signal of 1 kHz. The optimum peak bias amount is detected with a high accuracy of ± 0.2 dB from the reproduced signal. The reproduced signal supplied to the rectifying circuit of the AutoBLE unit is converted to a DC-voltage, which is then converted into a digital quantity. The microprocessor determines the maximum reproduced level. This peak bias value is detected twice for both Lch and Rch, and the average value is obtained. Therefore, compared with the method of determining with only one channel or only one peak bias value, high reliability is achieved.
Once the bias is set, the next step is to adjust the optimum recording level, again using a test signal of 1 Hz and varying the recording current in 64 steps so that the playback 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 changes the compensation amount of the recording equalizer in 64 steps to flatten the frequency response.
When all these adjustments have been made, the microprocessor instructs the tape to automatically rewind to the point before the adjustment was started and enters the recording standby state.
The AutoBLE system's adjustment status is indicated by three LEDs, one for the recording bias, one for the recording level, and one for the recording equalizer. The LEDs are designed to blink during adjustment and remain on when adjustment is complete.
In addition, three LEDs flash simultaneously to warn of errors due to incorrect position of the tape selector, etc.
A built-in memory back-up battery maintains the memory of the microprocessor during power-off, power failure, unplugged or unattended recording.
The capstan motor uses a quartz PLL D. D> coreless motor. The magnet (6 poles) attached to the rotor and the stator (9 coils) face each other in a planar manner. This realizes a high starting torque of 180g-cm.
In addition, because the DC-motor uses a permanent magnet that does not use an iron core for the rotor, there is no magnetic unevenness, no microvibration due to cogging or torque ripple, and the flutter components that are particularly harmful to audibility are greatly reduced. Moreover, it adopts a direct drive system in which the rotation of the motor is the rotation of the capstan as it is. Unlike a system in which the capstan is driven via a transmission mechanism, the performance of the coreless motor is stable as it is for tape running.
In addition, the capstan uses a 3 mm diameter thick shaft type. Even with the same direct drive system, the rotational speed of the motor can be further reduced. This reduces rotational unevenness and vibration caused by motor shaft runout and greatly improves mechanical durability.
The servo mechanism uses a quartz PLL that samples and holds the reference signal of a crystal oscillator with a high precision of ± 0.004% or less.
The speed detection mechanism of the motor itself employs a highly accurate all-round integration method, in which an AC signal is generated by a 60-pole magnet attached to the entire circumference of the rear surface of the capstan motor rotor and a low-impedance print pattern coil with the same number of poles facing the magnet. The AC signal is then integrated over the entire circumference. By this method, the accuracy of the quartz PLL is further improved and noise reduction is achieved.
In addition, Pioneer has adopted a contact-free switching mechanism using a Hall element originally developed by Pioneer for the switching of the magnetic pole of the motor realizes quiet and smooth rotation.
Equipped with a pitch control mechanism that can vary the pitch during playback by ± 6% (auto cancel during recording)
Quartz PLL The drive power of the D. D. capstan motor is supplied to the flywheel for driving the sub-capstan through the transmission belt, and the tape is run by two capstan in a closed-loop dual capstan system.
Modulation noise caused by tape vibration during tape travel is cut off from within the loop, enabling high-quality recording and playback.
In addition, the rotation speed of the sub-capstan side is slightly slower than that of the D. D. capstan, and uniform tape tension is continuously applied in the loop. By this design, good head touch is always obtained from the beginning of winding to the end of winding, and not only level fluctuation and drop-out are prevented, but also reliability of the AutoBLE is improved.
In addition, by changing the diameters of the left and right pinch rollers, the peak components of the wow flutter can be dispersed. In this way, of achieving high-fidelity reproduction.
The reel drive motor uses a high-torque coreless motor with less torque ripple and cogging, reducing uneven winding of the tape even during high-speed winding.
It uses an ATLC mechanism that automatically removes tape slack when the cassette tape is mounted.
It uses a newly developed improved reel shaft and has a high degree of connection with the cassette tape hub and prevents small fluctuations in tape tension.
A circuit configuration driven by ± 2 DC power supply is adopted. The first stage of both the reproduction equalizer amplifier and flat amplifier is a differential amplifier configuration with super low-noise PNP transistor, and the last stage of the equalizer amplifier is a push-pull complimentary service configuration with PNP and NPN to achieve a wide dynamic range and low noise.
The recording amplifier uses first stage differential and final stage pure complimentary service, and has a dynamic margin of 25 dB (1 kHz) from the reference level.
The bias amplifier has a stable circuit configuration in which the oscillation section that employs a voltage stabilization circuit and the output amplifier section for bias supply are made independent of each other, and the bias amount is changed between the bias oscillator and the output amplifier for fine adjustment.
The third stage of third stage of this bias supply amplifier uses PNP and NPN transistors to reduce the complimentary service impedance and realizes constant-current drive of the bias in the recording head.
By applying NFB after improving the bare characteristics in this way, the strain rate is greatly reduced and the bias drift characteristics with respect to temperature and time are also greatly improved.
A microprocessor applied 2-color FL level meter is used.
The level display uses 24 segments per channel and is designed to cover -30dB to + 8 dB. When the level is less than 0 dB, dB and orange when the level is more than 0 dB.
In addition, this FL meter can be used by switching the response characteristics to three levels of average, peak, and peak hold according to the program source.
It is equipped with an electronic memory function that enables tape play such as memory stop, memory play, counter repeat, and end repeat.
Uses pure electronic operation buttons controlled by IC logic circuit.
Equipped with an MPX filter release switch, Dolby system, Rec mute mechanism, timer standby mechanism, bias fine adjustment volume, monitor switch, etc.
It uses a full open loading system that securely holds the cassette half and allows smooth attachment and detachment.
Microphone and line mixing is possible.
Equipped with output volume.
.JPG)
.JPG)
.JPG)
.JPG)
.JPG)
.JPG)
.JPG)
Model Rating
| Type | Compact Cassette Tape Deck | ||||||||
| Heads | Recording heads : ribbon sendust heads Playhead : ribbon sendust head Erasing Head : Special Alloy Head |
||||||||
| Motor | For constant speed drive : Quartz PLL direct drive coreless capstan motor For Reel Drive : High Torque Coreless Motor |
||||||||
| Quick winding time | 75 seconds or less (C-60) | ||||||||
| Uneven rotation | 0.03% or less (WRMS) | ||||||||
| Frequency characteristic |
|
||||||||
| Signal-to-noise ratio (3rd harmonic distortion rate 3% Audibility correction) |
Dolby off : 60 dB or more Dolby on : 70 dB or more (5 kHz or more) |
||||||||
| Distortion factor | 1.0% or less (0 dB) | ||||||||
| Input Sensitivity / Maximum Allowable Input / Impedance |
Line : 65mV/15V/100k Ω, Pin Jack Microphone : 0.3mV/100mV/10k Ω, 6 mm Diameter Jack (Applicable Microphone Impedance : 250 Ω ~ 10k Ω) |
||||||||
| Reference output level / maximum output level / Impedance |
Line : 450mV/640mV/50k Ω, Pin Jack Headphones : 63mV/90mV/8 Ω, 6 mm Diameter Stereo Jack |
||||||||
| Semiconductor used | IC:42 Transistor : 194 Diode : 124 (Zener Diode : 16, LED : 19) Photointerrupter : 1 |
||||||||
| Power supply voltage | 100 VAC, 50Hz/60Hz | ||||||||
| Power consumption | 45W | ||||||||
| External dimensions | Width 420x Height 217x Depth 390 mm | ||||||||
| Weight | 18kg |