Audio Database

Image of SA-810
Commentary

This is a stereo pre-main amplifier with an emphasis on output characteristics of wide-band and low distortion factor. It adopts a positive and negative two power supply system for all circuits, and a differential amplifier is installed in the first stage of each section.

The equalizer consists of two can-shield transistors with little noise variation with time and two low-noise transistors for a first stage differential amplifier with three stage direct connection NFB.
Since the differential amplifier can apply 100% of the DC NFB, the DC stability is improved, and by using carefully selected elements, high S/N and low distortion characteristics are obtained.

By using nichrome evaporated metal film resistor (error of 1%) and Styrofoam capacitor (error of 2%) for NFB element and NFB receiving element of the equalizer, the accuracy of ± 0.2 dB is achieved in RIAA deviation of 30 Hz to 15000 Hz.

There are two input circuits for both Phono and AUX. The level of Phono2 and AUX2 can be controlled for the straight input of Phono1 and AUX1.
In particular, the Phono2 circuit is designed to control the level without affecting the input impedance and dynamic margin when using a high-output cartridge. This circuit is useful for alternate playback using two cartridges with different outputs or for comparative listening.

By the positive and negative two power supply system, the input / output point is always kept near 0 potential, and the shock noise caused by switch switching is drastically reduced.

The control circuit for the bass and treble is a twin-tone control that can be divided into the main and sub control.
Main gain and loss characteristics of 1 kHz, Bass gain and loss characteristics of ± 10 dB at 100 Hz, and Treble gain and loss characteristics of ± 10 dB at 10 kHz are obtained.
Sub can be controlled by ± 5 dB at 50 Hz for bass and ± 5 dB at 20 kHz for treble.
By combining and controlling Main and Sub, approximately 2000 different tone characteristics can be created.

A level setting mechanism is provided to eliminate the inconvenience of reducing the volume at night, when the volume is adjusted by a small control range near the MIN point of the volume control.
This circuit can be switched in three stages of 0 dB, -15dB and -30dB, and the whole level can be attenuated according to this indication, so that it can always be adjusted in a useful rotation range near the center of the volume.

The control section also uses a differential amplifier with 100% DC NFB at the first stage, and has a 3-stage direct connection NF type circuit configuration.
A can-shield transistor is used in the first stage to obtain high reliability even with long-term aging.

Equipped with a tone defeat switch that can immediately obtain flat characteristics.

Low/High subsonic filters that cut sharply at 12dB/oct are built-in.

The power circuit uses a one stage differential pure complimentary service OCL circuit.
In addition, we have adopted PNP and NPN type drivers and power transistors selected according to the pair characteristics.
In addition, a large radiator, a current limiting circuit, and an electronic protection circuit are employed to ensure that a large power can be obtained.

It is equipped with a protective circuit combining an electronic circuit and a power relay.

Equipped with an audio muting switch, the volume can be instantly reduced by -20dB.

Equipped with speaker output jacks for enjoying A, B and A + B.

In addition to the pre-main split switch, the power amplifier can also be equipped with a subsonic filter when it is separated. It is also fully equipped with various auxiliary circuits.

Actually measured data is attached to each unit.

Model Rating
Type Stereo pre-main amplifier
Power Amplifier Unit
Circuit system Pure complimentary service OCL
Effective power
20 Hz to 20000 Hz, both channel drive : 40W + 40W (8 Ω)
45W + 45W (4 Ω)
1 kHz, both channel drive : 44W +44W (8 Ω)
50W + 50W (4 Ω)
1 kHz, single-channel drive : 50W/50W (8 Ω)
60W/60W (4 Ω)
Harmonic distortion factor Effective power : 0.3% or less
1W output : 0.05% or less
Cross modulation distortion factor Effective power : 0.3% or less
1W output : 0.05% or less
Output Bandwidth (IHF, both channel drives) 5 Hz ~ 40 kHz (Distortion Factor 0.3%)
Frequency characteristic 7 Hz to 80 kHz, + 0 -1dB
Input Sensitivity / Impedance Power Amp In : 500mV/50k Ω
Output terminal Speaker : A, B, A + B (4 Ω ~ 16 Ω)
Head Phones : 4 Ω ~ 16 Ω
Damping factor (1 kHz, 8 Ω) 60 or higher
S/N (IHF, short circuit A network) 95 dB or more
Residual noise (8 Ω, pre + power amplifier) 1 mV (0.13 μ W) or less
Subsonic filter 8Hz(12dB/oct)
Preamplifier Section
Circuit system Equalizer amplifier : first stage differential 3-stage direct connection NF type
Control Amplifier : First stage differential 3-stage direct connection NF type
Input Sensitivity / Impedance Phono1 : 2.5mV/50k Ω
Phono2 : 2.5 mV to 5mV/50k Ω
Phono maximum allowable input (rms/p-p) : 250mV/700mV
MIC : 2.0mV/50k Ω
Tuner : 150mV/100k Ω
AUX1 : 150mV/100k Ω
AUX2 : 150 mv ~ 1.5V/50k Ω ~ 100k Ω
Tape Monitor1, 2 : 150mV/100k Ω
Tape Monitor2 (DIN) : 150mV/100k Ω
Output Level / Impedance Tape Rec1, 2 : 150 mv
Tape Rec2 (DIN) : 30mV/80k Ω
Pre Out : 2V/5 Ω
Harmonic distortion factor (20 Hz to 20 kHz) Not more than 0.05%
Frequency characteristic Phono (RIAA deviation) : 30 Hz to 15 kHz, ± 0.2 dB
MIC : 10 Hz to 10 kHz, + 0 -1dB
Tuner, AUX, TapeMonitor : 10 hz to 70 khz, + 0 -1dB
Tone control
Bass Main : ± 10 dB (100 Hz)
Sub : + / - 5 dB at 50 Hz
Treble Main : ± 10 dB at 10 kHz
Sub : ± 5 dB (20 kHz)
Filter Subsonic:8Hz(12dB/oct)
Low:30Hz(12dB/oct)
High:8kHz(12dB/oct)
Loudness contour at volume -40dB +10dB(100Hz)
S/N (IHF, short circuit A network) Phono : 80 dB or more
MIC : 70 dB or more
Tuner, AUX, Tape Monitor : 90 dB or higher
Muting -20dB
Level Set (3-Step Switching) 0 db, -15dB, -30dB
<General>
Semiconductor used Transistor : 49
Diode and others : 25
Power supply voltage 100 VAC, 50Hz/60Hz
Rated power consumption 105W
Maximum Power Consumption 260W
Power outlet Power switch interlock 1, non-interlock 2
External dimensions Width 430x Height 138x Depth 341 mm
Weight 12.1kg