Stereo Power Amplifier (1977-80)
The Spec-4 employs DC construction which excludes capacitors from the NFB circuits and uses a dual transistor differential amplifier with a current mirror circuit in the 1st stage.
This provides a stable operation and also high gain over a wide frequency range.
The pre-driver stage is a class A circuit with a regulated current circuit for the load.
This makes for high gain amplification with superior linearity.
Furthermore, there is an overdrive limiter and power limiter circuit which is designed to protect the power transistors and make for added reliability.
Power output: 150 watts per channel into 8Ω (stereo)
Frequency response: 5Hz to 100kHz
Total harmonic distortion: 0.01%
Damping factor: 100
Input sensitivity: 1V
Signal to noise ratio: 115dB
Speaker load impedance: 4Ω to 16Ω
Semiconductors: 2 x IC, 61 x transistors, 62 x diodes
Dimensions: 480 x 187 x 445mm
instruction/owners manual - Herbman1975
service manual - Herbman1975
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Pioneer Power Amplifiers