Pioneer M-Z1a

Commentary

This is a non-feedback monaural power amplifier that has been carefully selected and polished from the parts in order to obtain the power required for power amplifiers and sound quality without distortion.

A super-linear circuit is used in the voltage amplifier section, and the non-linearity of the transistor is canceled by the transistor having the non-linearity of the reverse mode. This method realizes linear amplification without using the NFB loop and solves the problem caused by NFB.

High-speed response LAPT (collective power transistor) is used for the output stage.
In order to obtain linearity, the current load per 1 stone is reduced and 6 units are used in parallel for pure class A operation.

For DC-stabilization of the output point, which is important for non-feedback amplifiers, we have adopted double-lock ドサーボ regulators to further improve the reliability of super linear circuits by suppressing the fluctuation of mid-point voltage.
In addition, the coupling capacitor, which causes the coloring of sound, is completely removed and all stages are directly connected, which further enhances the features of the non-feedback amplifier.

Although it is a monaural amplifier, two power transformers are used as transformers.
The power supply impedance is reduced by equivalent parallel connection, and the power supply drive to the output stage is strengthened.

In order to eliminate the cause of sound quality degradation, we have developed and adopted a glass-case capacitor in which the case of the capacitor is replaced with glass instead of aluminum, the inner surface of the glass case is coated with carbon, and the electrode foil is improved.

A high-performance and highly reliable mica capacitor is used for the small-capacity capacitor. It is enclosed in a resin case with a special high-density epoxy resin to prevent intermodulation distortion caused by electrode vibration.

The lead part has been replaced with an iron cap and resistance with brass cap carbon has been adopted to thoroughly suppress strain.

Focusing on the slight distortion caused by magnetic materials, we use non-magnetic aluminum materials for the chassis and frame, and coat the inner surface with special resin to ensure uniform shielding effects.

The printed circuit board uses glass epoxy with high mechanical strength and excellent high-frequency characteristics.
In addition, the copper foil has a thickness of 140 μ m, about four times that of conventional ones, thereby reducing DC resistance and inductance.

In order to improve sound quality, oxygen-free copper is used for wiring for signal systems, and oxygen-free copper is also used for other signal flow areas and connecting fittings.

The pin plug cord uses a star quad structure made of oxygen-free copper to reduce cord self-inductance and achieve low-loss and flat transmission characteristics up to high frequencies.

The power cord uses a double insulated large-capacity cord, and the polarity is unified from the core wire of the power cord to the internal circuit, so that the AC line and polarity can be matched.

A protection circuit is used to detect overload, midpoint voltage, and power supply voltage abnormality.
If this causes an abnormal change in the midpoint voltage due to an accident such as a short-circuit of the speaker terminal, disconnect the speaker and power amplifier.
It operates as a muting circuit when the power switch is turned ON or OFF.

Equipped with a 20-point LED peak power indicator.
Using a logarithmic compression circuit, the peak value is indicated from 0.001W to 100W without range switching.
It is also equipped with a peak hold function, making it convenient for reading peak values.

Model Rating

Type	Non-feedback monaural power amplifier
Effective output (20 Hz to 20 kHz)	60W (8 Ω)
Input Sensitivity / Impedance	Input : 1V/50k Ω
Output terminal	Speaker : 8 Ω
Damping factor	80 or More (20 Hz ~ 20 kHz, 8 Ω)
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	220W (Electrical Appliance and Material Control Law)
AC outlet	Power switch not linked : 1 system, 100W
External dimensions	Width 220x Height 185x Depth 440 mm
Weight	19.1kg