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Pioneer Spec-4

Stereo Power Amplifier (1977-80)

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Pioneer Spec-4


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

Weight: 24.5kg


Related Catalogues

Hi-Fi Stereo

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re: Spec-4

Hello everyone, and thanks for all your generous contributions to this site. I own a Pioneer Spec-4 amp Type S, which is apparently the "General Export" model. Would anyone have available pages 41-48 of the Service manual. These pages cover the differences between the 2 models (USA and General export) which, at a glance, appear to be several.

Thanks in advance.

Ed Vaioli
Corning, NY USA

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