Pioneer SA-8900II
¥ 79,800 (released in 1976)
Commentary
This pre-main amplifier achieves high sound quality by using an excellent circuit structure and carefully selected high-precision parts.
The EQ consists of a first stage differential, a 3-stage direct connection, a final stage class A operation pure complimentary service SEPP and two positive and negative power supplies. In addition, the NFB device for obtaining EQ deviation uses carefully selected elements such as a nichrome evaporated metal film resistor with a resistance error of ± 1% and a temperature characteristic of ± 50ppm/c, and a styrene capacitor with a capacitance error of ± 2%. These elements provide excellent characteristics.
A voltage of ± 30 V is applied to this circuit. The maximum output of the equalizer amplifier is 18 V, the maximum allowable input is 300 mV, and the sensitivity is 2.5 mV. This circuit has a large dynamic margin.
In order to maximize the performance of many cartridges, both Phono1 and 2 are equipped with cartridge load switching switches that can independently select 4 types of load resistance and 4 types of load capacity.
The flat amplifier in the control section consists of a first stage differential and a two stage direct-coupled circuit. By using differential amplification in the first stage, the operating point is selected in the linear region of the transistor to reduce distortion.
Both Bass and Treble use a twin-tone control with main and sub two variable positions. Variable uses a switch-type volume in 2 dB steps.
A 32-step attenuator is used for the volume, and the gang error between the left and right channels is as small as 0.5 dB or less, and the error with the indicated value on the panel surface is within ± 0.5 dB.
In addition, it is equipped with a muting lever of -20dB, and delicate volume adjustment is possible by combination.
The power amplifier circuit is composed of ± 2 power supply, 2 stage differential amplifier current mirror circuit and final stage parallel push-pull pure complimentary service OCL circuit.
The input is a differential amplifier to suppress voltage fluctuations due to changes in external temperature and to reduce distortion. The pre-driver stage is made to be a constant current by the current mirror circuit to increase bare characteristics and to reduce distortion with sufficient NFB, and at the same time, even order harmonic distortion is suppressed. The NFB loop from the output stage has a large time constant so that the circuit operation is similar to that of a DC amplifier and phase shift is reduced. The output stage is a parallel push-pull to stably take out a large output.
The radiator uses an efficient chimney style to enhance thermal stability.
The power supply section uses two power transformers with independent left and right channels, and consists of two heavyweight transformers and a 12,000 μ Fx4 large-capacity capacitor.
With this two power transformer configuration, channel crosstalk is improved by eliminating channel interference at the power supply.
The protection circuit consists of a highly reliable twin-contact power relay and a fast response electronic circuit.
It also eliminates power-on clicks.
It is equipped with auxiliary functions such as pre-power separation terminal, 2-system tape monitor, tone on-off switch, loudness contour, low-cut (subsonic) and high-cut filter.
.JPG)
.JPG)
Model Rating
| Type | Stereo pre-main amplifier | ||||
| Power Amplifier Unit | |||||
| Circuit system | 2-stage all-stage direct-coupled parallel PP pure complimentary service OCL | ||||
| Effective power (Both channel drive, 20 Hz to 20 kHz) |
100W + 100W (4 Ω) 80W + 80W (8 Ω) |
||||
| Harmonic distortion factor (20 Hz to 20 kHz) | 0.05% (at effective output) 0.01% (8 Ω at 40W output) 0.01% (8 Ω at 1W output) |
||||
| Cross modulation distortion factor (50Hz:7kHz=4:1) |
0.05% (at effective output) 0.01% (8 Ω at 40W output) 0.01% (8 Ω at 1W output) |
||||
| Output Bandwidth (IHF, both channel drives) | 5 Hz to 45 kHz (Distortion Factor 0.05%) | ||||
| Frequency characteristic | 5 Hz to 100 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 |
||||
| Damping factor | 30 (20 Hz ~ 20 kHz, 8 Ω) | ||||
| S/N | 110 dB (IHF, A-network, short circuit) | ||||
| Preamplifier Section | |||||
| Circuit system | Equalizer amplifier : First stage differential 3-stage direct connection Class A SEPP Tone control part : first stage differential 2-stage direct connection flat amplifier, NFB type twin tone |
||||
| Input Sensitivity / Impedance | Phono1, 2 : 2.5mV/10k Ω, 25k Ω, 50k Ω, 100k Ω Cartridge Load Capacity : 100 pf, 200 pf, 300 pf, 400 pf (for both Phono1 and 2) Tuner, Aux, Tape play1, 2 : 150mV/50k Ω |
||||
| Phono maximum allowable input | Phono1, 2 : 300 mV (1 kHz, harmonic distortion rate 0.05%) | ||||
| Output Level / Impedance | Tape Rec1, 2 : 150 mv Pre out : 1V/2k Ω, 10V/2k Ω (max) |
||||
| Harmonic distortion factor (20 Hz to 20 kHz) | 0.01% (1 V Output) 0.1% (10 v Output) |
||||
| Frequency characteristic | Phono : 20 Hz to 20 kHz ± 0.2 dB Tuner, Aux, and Tape play : 5 hz to 50 khz + 0 to 1 db |
||||
| Tone control |
|
||||
| Filter | Low : 15 Hz, 6dB/oct. High : 8 kHz, 6dB/oct. |
||||
| Loudness contour (Volume -40dB) |
+6dB(100Hz) +3dB(10kHz) |
||||
| Muting | -20dB | ||||
| S/N (IHF, A-network Short circuit) |
Phono:75dB Tuner, Aux, Tape play : 95 dB |
||||
| <General> | |||||
| Semiconductor used | Transistor : 55 Diode, etc. : 33 pcs |
||||
| AC outlet | Power switch interlock : 2 systems Power switch not linked : 2 systems |
||||
| Power supply voltage | 100 VAC, 50Hz/60Hz | ||||
| Power consumption | 200W (Electrical Appliance and Material Control Law) 560W maximum |
||||
| External dimensions | Width 420x Height 150x Depth 376 mm | ||||
| Weight | 16.2kg | ||||