Pioneer A-150

Commentary

Pre-main amplifier equipped with dynamic non-switching amplifier.

Pioneer's original dynamic power supply system is used in the power supply section.
This is the low voltage part (V_LHigh voltage section (V)_HThis highly efficient power supply circuit drives at a low voltage section when the signal level is normal, and at a high voltage section when the signal level is Dainyu Chikara. This greatly reduces losses at the output stage and provides high power with room.
In addition, in order to realize the full performance, the power source impedance has been reduced by installing a large EI transformer and 44,000 μ F electrolytic capacitor for audio.

The power amplifier section is equipped with a non-switching circuit, which controls the bias current according to the input signal to keep the transistor in the operating state at all times, thereby eliminating the generation of switching distortion from the root.

In order to make the most of the characteristics of the MC cartridge, the MC transformer system with excellent noise characteristics is adopted. In addition, by providing impedance switching, matching with a wide range of cartridges is possible.
In addition, the boost ratio of the MC transformer is reduced to half of that of the conventional transformer by using the gain switching of the equalizer amplifier, and the high-frequency characteristics are greatly improved by reducing the inductance and capacitance between lines due to the small number of windings. The transformer output voltage is small even in the low-frequency range, so the magnetic saturation margin is large and it is designed to be resistant to excessive input.
It also has excellent phase characteristics, low DCR (direct current resistance), and good sound quality with good damping.

Equipped with line straight function which passes tone control circuit and mode circuit with one switch.

Each part is carefully selected to obtain high sound quality.
By using semiconductors for non-magnetic lead wires, brass caps and copper-lead wires for main resistors, copper-lead wires for capacitors, non-magnetic nickel-phosphorus electroless plating for AC plugs, oxygen-free copper for main wiring materials, and copper-cap tin-plated audio fuses, we have thoroughly reduced the occurrence of magnetic distortion.
In addition, a copper foil printed circuit board of 70 μ m is adopted for the board, and ground impedance and signal line impedance are lowered and sound quality is improved.

A very thick oxygen-free copper power cord is used for the power cord.
By using 37 oxygen-free copper wires of 0.26 mm diameter, loss in wire wire is reduced, and non-linear strain is greatly improved compared with general soft copper wire.
In addition, polyethylene is used as the material for the internal insulation, and the dielectric constant is reduced to 1/4 compared with the conventional poly Enka vinyl. By reducing the inter-line capacitance, the quality is reduced and the resin height is increased to prevent conductor vibration.
In addition, the polarity of the AC line is indicated on the rear panel and AC plug. Moreover, the way of winding the transformer is also thoroughly managed.

A silent radiator is used to prevent the resonance of the radiator from contaminating the reproduced sound.
The strength of the fins is increased by connecting the tips of the fins to a chimney type, and the resonance mode is dispersed by randomly arranging the fins of different heights.

Equipped with an LED peak power indicator that displays the peak value of the output at 3 points using a circuit with excellent transient response.
In addition, a sensitivity switch is provided for small output power and large output power, making it possible to correspond to the playback level.

Model Rating

Type	Pre-main amplifier
Effective power	150W + 150W (8 Ω, 20 Hz to 20 kHz, both channel drive)
Harmonic distortion factor (20 Hz to 20 kHz)	0.003% (at effective output)
Intermodulation distortion factor (50 hz : 7 khz = 4 : 1)	0.003% (at effective output)
Output bandwidth	5 Hz ~ 55 kHz (IHF, both channel drive, THD0.01%)
Output terminal	Speaker (4 Ω ~ 16 Ω) : A, B, A + B Tape Rec1, 2 : 150 mv
Damping factor	80 (20 Hz ~ 20 kHz, 8 Ω)
Input Sensitivity / Impedance	Phono MM : 2.5mV/50k Ω Phono MC : 0.15 mv, 0.25mV/3 Ω, 40 Ω Tuner, CD/AUX, Tape Play1, 2 : 150mV/50k Ω
Phono maximum allowable input (1 kHz, THD0.003%)	MM:300mV MC:18mV
Frequency characteristic	Phono MM : 20 Hz to 20 kHz ± 0.2 dB Tuner, CD/AUX, Tape Play : 5 hz to 100 khz + 0 to 3 db
Signal-to-noise ratio (IHF, A-network, short circuit)	Phono MM:90dB Phono MC:76dB Tuner, CD/AUX, Tape Play : 110 dB
Tone control	Bass : ± 10 dB (100 Hz) Treble : ± 10 dB (10 kHz)
Filter	Low : 15 Hz, 6dB/oct.
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption (Electrical Appliance and Material Control Law)	300W
External dimensions	Width 420x Height 150x Depth 420 mm
Weight	16.8kg