Stereo Power Amplifier (1983-84)
The first stage and the second stage of the SM-1000 power amplifier are push-pull differential amplifiers using dual transistors. They are coupled via an emitter follower buffer amplifier. Thus, all the circuits from the input to the final stage are pure complementary push-pull circuits.
The final stage uses super linear 3-stage Darlington construction with three circuits each of which consists of three drivers and power transistors connected in parallel are connected in parallel. A total of 36 power transistors are used for both channels and they are mounted on a Tunnel Heat Dissipator which achieves highly efficient heat dissipation.
The model SM-1000 is equipped with large size power meters for checking output levels and balance. These power meters detect peak values of output power and they are graduated in rms values. Meter readings indicate output power into an 8 ohm load. The scale is subject to logarithmic compression, so that a wide range of power can be read without switching the range. These meters have a flat frequency response over a wide frequency range and can follow music signals with rapid rises.
Each channel is provided with an exclusive power transformer, resulting in stable characteristics. The primary lines of both transformers are wired independently, and therefore, if one channel is defective, the other channel can operate without any problem.
The overload protection circuit detects excessive output current and voltage to keep the operation of the drive transistors within the preset area of safety operation. This protection circuit has fast response so that reproduced programs are not degraded even if the circuit operates.
Power output: 400 watts per channel into 8Ω (stereo)
Frequency response: 1Hz to 100kHz
Total harmonic distortion: 0.015%
Damping factor: 300
Input sensitivity: 2.83V
Dimensions: 438 x 178 x 550mm
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