Pioneer A-570
¥ 59,800 (released in 1980)
Commentary
Pre-main amplifier with non-switching circuit.
The power amplifier section uses a non-switching circuit, a circuit technology unique to Pioneer.
A high-speed bias servo circuit controls the bias current according to the input signal. This is a unique method that keeps the transistor in an always operating state. By this method, the transistor does not switch in principle, so the switching distortion, which is common with class B amplifiers, is suppressed to 0.
In addition, crossover distortion is thoroughly pursued, and a power transistor with excellent pair characteristics is adopted, and the optimum point of the transistor is set to realize input / output characteristics with high linearity.
Random access parts such as function switches and speaker selector switches are crystal brown self-illuminated and use one touch push buttons.
It is equipped with a Rec selector which expands the function of the amplifier such as air check of FM broadcasting while listening to the record.
The function switch, REC selector and speaker switch are equipped with an upper priority circuit to prevent operation failure caused by pressing several switches simultaneously.
The power section has a DC amplifier configuration that eliminates capacitors that adversely affect sound quality, thereby suppressing the degradation of damping caused by capacitors, phase shift in the middle and low frequencies, and transient intermodulation distortion.
With the aim of improving the sound quality of the overalls, each part is carefully selected.
In particular, the power section uses Super Linear RET (Ring Emitter Transistor), a group transistor with excellent linearity in the high-frequency range, which enhances the performance of non-switching circuits.
The radiator uses a T-shaped skive fin with more than 50% increased heat radiation effect to achieve stable sound quality even for continuous high-power playback.
The Phono input uses an ICL type FET differential input circuit.
An ICL type FET differential input circuit is also used in the flat amplifier section.
Equipped with an MC position to which an MC cartridge can be directly connected. The gain can be changed by switching the switch.
The tone control uses a center defeat method that jumps the tone circuit at the center position to obtain a flat characteristic.
It is equipped with a subsonic filter that cuts out unwanted ultra-low frequency components (15 Hz or less) caused by record warping, etc.
Equipped with a loudness contour that is convenient for low volume.
Model Rating
Type | Pre-main amplifier |
Effective power | 70W + 70W (8 Ω, 0.008% Distortion Factor, 20 Hz to 20 kHz, Double-channel Drive) |
Harmonic distortion factor (20 Hz to 20 kHz) | 0.005% (8 Ω at 35W output) |
Intermodulation distortion factor (50 hz : 7 khz = 4 : 1) | 0.005% (8 Ω at 35W output) |
Output bandwidth | 5 Hz to 50 kHz (IHF, double-channel drive, 0.01% distortion) |
Damping factor | 60 (20 Hz ~ 20 kHz, 8 Ω) |
Input Sensitivity / Impedance | Phono MM : 2.5mV/50k Ω Phono MC : 0.25mV/0.1k Ω Tuner, AUX, Tape Play1, 2 : 150mV/50k Ω |
Phono maximum allowable input (1 kHz, 0.01% distortion rate) |
MM:250mV MC:25mV |
Output Level / Impedance | Tape Rec1, 2 : 150mV/2.2k Ω Speaker : A / B / Off, 4 Ω ~ 16 Ω |
Frequency characteristic | Phono : 20 Hz to 20 kHz ± 0.2 dB Tuner, AUX, Tape Play1, 2 : 5 Hz to 80 kHz + 0 -3dB |
Signal-to-noise ratio (IHF, A-network Short circuit) |
Phono MM:89dB Phono MC:72dB Tuner, AUX, Tape Play1, 2 : 110 dB |
Tone control | Bass : ± 10 dB (100 Hz) Treble : ± 10 dB (10 kHz) |
Subsonic filter | 15 Hz, 6dB/oct. |
Loudness contour (at Volume -40dB) | + 8 dB (100 Hz), + 3 dB (10 kHz) |
Muting | -20dB |
Power supply voltage | 100 VAC, 50Hz/60Hz |
Power consumption (Electrical Appliance and Material Control Law) | 145W |
External dimensions | Width 420x Height 120x Depth 368 mm |
Weight | 9.9kg |