Pioneer : SA-8900 & TX-8800 Amplifier and Tuner Set (100v) - 1976
This is a pre-main amplifier equipped with twin tone control as well as improving the precision of each circuit for higher sound quality.
The power amplifier section has one stage of differential amplifier and is equipped with a pure complimentary service OCL circuit directly connected to all stages with parallel push-pull configuration. By adopting parallel push-pull, linearity of current characteristics is improved, and distortion is suppressed to realise large output. In addition, since the pre-driver is a stabilised power supply, transient crossover distortion in minute output is eliminated.
In addition, the stability of the circuit is improved by supplying ± 2 power supplies and adopting a differential amplifier. Furthermore, by installing a bias compensation circuit, the fluctuation of offset voltage is suppressed even with the change of external temperature, and the characteristics are further stabilized.
The equalizer is a 3-stage direct-coupled circuit with ± 2 power supplies using a low-noise transistor at the first stage. By using the second stage as an emitter follower, a large gain can be obtained at the first stage, and a large amount of stable NFB is applied.
In addition, by using ± 2 power supplies, the circuit is more stable and noise is prevented when switching, and by using carefully selected NFB elements with less deviation, the characteristics are improved.
Power output: 80 watts per channel into 8Ω (stereo)
Frequency response: 5Hz to 50kHz
Input sensitivity: 2.5mV (MM), 150mV (line)
Signal to noise ratio: 75dB (MM), 95dB (line)
Output: 150mV (line), 1V (Pre out)
Speaker load impedance: 4Ω to 16Ω
Dimensions: 420 x 150 x 376mm
An AM/FM stereo tuner that inherits the TX 8900 technology and aims for high performance beyond the class.
The front-end section uses a four row frequency linear varicon, and for high-frequency amplification, low-noise, high-linearity FET is used to improve sensitivity and interference rejection capability.
In the IF stage, selectivity characteristics are improved by making the 2-element ceramic filter with excellent phase characteristics into a 3-stage configuration.
The IC incorporates more than 200 elements in total into a single IC, with five stage limiters to adjust the waveform and improve various characteristics.
A PLL circuit is used in the MPX section.
Stable separation is obtained by exclusive high integration IC of the PLL circuit.
A muting circuit using a relay is built in to eliminate noise between stations at the time of detuning.