Pioneer SA-8900
¥ 78,000 (around 1975)
Commentary
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 realize large output. In addition, since the pre-driver is a stabilized 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.
The flat amplifier in the control section is a 2-stage direct connection type by the combination of PNP-NPN. By applying NFB in both AC and DC, distortion can be reduced, and it can be sent to the tone circuit with low impedance, so that the tone circuit can operate under more ideal conditions.
In addition, the stability of the midpoint potential is maintained by ± 2 power supply, and noise at switching is eliminated.
The NF-type tone circuit is used, and Pioneer's original twin-tone control that can change the amount of NFB with a switch-type resistor with less deviation is used. This greatly expands the control function.
In addition to the main control, this twin-tone control has sub controls. The main control can be adjusted by ± 8 dB in 2 dB steps, and the sub control can be adjusted by ± 6 dB in 2 dB steps. The main control can be used as a general tone control when only the main control is used. The sub control can be used as a general tone control when only the sub control is used to change only the very low and very high frequencies.
In addition, a tone on/off switch is provided so that flat characteristics can be obtained.
Two tape decks can be connected. By turning on the duplicate switch, you can freely dub tapes from 1 to 2 or from 2 to 1.
It is equipped with a protective circuit with a built-in relay and reduces noise when the power is turned on/off.
Equipped with low cut and high cut filters.
It is also equipped with functions such as loudness contour and muting.
Model Rating
Type | Stereo pre-main amplifier | ||||
Power Amplifier Unit | |||||
Circuit system | Differential 1-stage all stages directly connected parallel PP pure complimentary service OCL | ||||
Effective output (both channels driven, 20 Hz to 20 kHz) | 75W + 75W (4 Ω) 60W + 60W (8 Ω) |
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Harmonic distortion factor (20 Hz to 20 kHz) | 0.1% or Less (Effective Output) 0.05% or Less (8 Ω at 30W output) 0.05% or Less (8 Ω at 1W output) |
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Cross modulation distortion factor | 0.1% or Less (Effective Output) 0.05% or Less (8 Ω at 30W output) 0.05% or Less (8 Ω at 1W output) |
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Output Bandwidth (IHF, both channel drives) | 5 Hz ~ 40 kHz (Distortion Factor 0.1%) | ||||
Frequency characteristic | 10 Hz to 80 kHz + 0 -1dB | ||||
Input Sensitivity / Impedance | Power amp in : 1V/50k Ω | ||||
Output terminal | Speaker A / B : 4 Ω ~ 16 Ω Speaker A + B : 8 Ω ~ 16 Ω Headphone : 4 Ω ~ 16 Ω |
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Damping factor (20 Hz to 20 kHz) | 30 or more | ||||
S/N | 100 dB or more (IHF, A-network, short circuit) | ||||
Preamplifier Section | |||||
Circuit system | Equalizer amplifier : Two positive and negative power supplies, three stages connected directly Control amplifier : Two power supplies (positive and negative), four elements configuration |
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Input Sensitivity / Impedance | Phono1 : 2.5mV/50k Ω Phono2 : 2.5 to 5mV/50k Ω Tuner, Aux, Tape PB1, 2, DIN : 150mV/50k Ω |
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Phono maximum allowable input (Harmonic distortion rate 0.1%, 1 kHz) |
Phono1:200mV Phono2 : 200 mV to 400 mV |
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Output Level / Impedance | Tape Rec1, 2 : 150 mv Tape Rec2 (Din) : 30mV/80k Ω Pre out : 1V/1k Ω |
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Harmonic distortion factor (20 Hz to 20 kHz) | Not more than 0.05% | ||||
Frequency characteristic | Phono (RIAA deviation) : 30 Hz to 15 kHz ± 0.3 dB Tuner, Aux, Tape PB : 7 7 hz to 40 khz + 0 to 1 db |
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Tone control |
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Filter | Low : 30 Hz, 12dB/oct. High : 8 kHz, 12dB/oct. |
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Loudness contour (Volume -40dB) | +8.5dB(100Hz) +4dB(10kHz) |
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Muting | -20dB | ||||
S/N (IHF, A-network Short circuit) |
Phono : 70 dB or more Tuner, Aux, Tape PB : 90 dB or higher |
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<General> | |||||
Semiconductor used | Transistor : 45 Diode, etc. : 27 pcs |
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AC outlet | Power switch interlock : 2 systems Power switch not linked : 1 system |
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Power supply voltage | 100 VAC, 50Hz/60Hz | ||||
Power consumption | 145W (rated) 380W maximum |
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External dimensions | Width 420x Height 150x Depth 345 mm | ||||
Weight | 12.6kg |