NIKKO A-800

Commentary

This is a pre-main amplifier that uses the know-how of NIKKO and pursues one rank higher quality.

The equalizer uses a 3-stage direct connection NF type. One newly developed PNP transistor is used for the first stage, FET is used for the second stage, and NPN transistor with high breakdown voltage and large collector loss is used for the last stage.

A pure complimentary service OCL circuit is used for the main amplifier.
The two stage differential amplifier circuit adopted in the first stage is equipped with a Zener diode to provide complete temperature compensation and stable operation.

The protective circuit is purely electronic, and relays and fuses are used together.
The relay is set to operate when a DC component of approximately 2 V is applied to the output terminal to protect the speaker and output transistor. It also has muting function when the power is turned on to prevent unpleasant shock sound and transient distortion sound when the power is turned ON/OFF.

The low filter and high filter have a frequency switching function.

The tone control circuit uses a low-impedance modified BAX circuit with two stage direct connection.
By operating the lever switch for both Treble and Bass, the turnover frequency can be changed in three stages.

The power supply is equipped with a large transformer and two 10,000 μ F smoothing capacitors.

Each of the two tape systems is equipped with an RCA terminal and a DIN terminal. The Tape 2 terminal is also located on the front panel and is designed to automatically cut Tape 2 on the rear panel.

Equipped with two phono input terminals.
In addition, the phono 2 terminal can switch the load impedance of the cartridge to 3 levels.

Equipped with a switch for separating the pre-part and main part, it is possible to develop a multi-channel system.

The speaker outputs can be connected to the Route 3.
When all the A / B / Cs are operated, only the A system is designed to operate. This prevents the danger of the load impedance of the main amplifier becoming extremely low.

Model Rating

Type	Pre-main amplifier
Circuit system	Main Part : OCL Pure complimentary service Circuit with two stage Differential Amplification Pre-part : 3-stage direct-coupled NF-type equalizer, 2-stage direct-coupled NF-type tone circuit
Main Amplifier Section
Music Power (IHF)	180W (8 Ω)
Rated effective output	Single-channel operation : When both channels are operating : 70W/70W (8 Ω, 1 kHz) 65W + 65W (8 ohm, 1 khz) 60W + 60W (8 Ω, 20 Hz to 20 kHz)
Output characteristic	20 Hz to 20 kHz -1dB (1% THD)
Frequency characteristic	10 Hz to 40 kHz ± 1 dB
Harmonic distortion factor	0.3% or Less (at Rated Output) 0.1% or Less (at 1W Output)
Cross modulation distortion factor	0.3% or Less (at Rated Output) 0.1% or Less (at 1W Output)
Preamplifier Section
Input Sensitivity / Impedance	Phono1 : 2.5mV/50k Ω Phono2 : 2.5mV/25k Ω, 50k Ω, 100k Ω Tuner, Aux1, 2, Tape1, 2 : 180mV/100k Ω
Signal-to-noise ratio	Phono1, 2 : 65 dB Tuner, Aux1, 2, Tape1, 2 : 80 dB
Phono maximum allowable input	300 mv (RMS, 1 kHz)
RIAA deviation	20 Hz to 20 kHz ± 0.5 dB
Tone control	Bass : 250 Hz, Defeat, 500 Hz Treble : 5 kHz, Defeat, 2.5 kHz
Loudness	+ 10 dB at 70 Hz, + 5 dB at 10 kHz
Low filter	Off, Subsonic (8 Hz), 50 Hz, switchable -3dB, 12dB/oct.
High filter	7 kHz, off, 12 kHz, switchable -3dB, 12dB/oct.
Muting	-20dB
<General>
Semiconductor used	Transistor : 46 FET : 2 Diode : 11 units Zener diode : 5 pcs
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	145W (at rated output)
External dimensions	Width 455x Height 151x Depth 345 mm
Weight	12.5kg