YAMAHA CA-800

Commentary

A stereo pre-main amplifier developed by inheriting CA-1000 technology.

As with the CA-1000, the main amplifier section uses a pure complimentary service OCL circuit directly connected to all stages of the first stage differential amplifier.
In addition, it is equipped with a class-B to class-A operation switching circuit, and it can be switched with one touch while keeping the volume constant.
It is also equipped with a large heat sinker and a two stage protection circuit that protects the power Tr and the speaker to ensure stable operation.

The power supply section uses a large-core power transformer with low voltage fluctuation even during class B operation, a 6800 μ Fx2 large-capacity capacitor, and a separately set constant-voltage power supply that drives all stages except the power stage to improve the stability of the entire amplifier.
The speaker protection circuit also functions as a power muting to prevent shock noise when the power switch is turned on.

The equalizer amplifier uses an NFB 4-stage direct-coupled circuit with low-noise transistors.
In addition to a high supply voltage of + 50 V constant voltage and an exciter follower type output stage with low output impedance, a circuit analysis (CAD method) using a computer is used to obtain low distortion factor and high stability.
The EQ elements are combined with a metal-coated resistor with ± 1% tolerance, a styrofoam capacitor with ± 1% tolerance and a 2% tolerance%/±, and a tantalum capacitor with no characteristic degradation is also used.
The Phono1 is equipped with an input impedance selector switch that can be switched in three stages.

For the tone control circuit, the Yamaha mixing NF and CR type is adopted using 3-stage connected amplifier with low distortion factor and high SN.
In the boost mode, the gain is increased by lowering the emitter impedance and reducing the amount of NF. In the cut mode, the gain is attenuated by CR. Therefore, flat characteristics without waviness can be obtained at the middle point of the knob.
At tone defeat, the circuit operates as a flat amplifier.

Equipped with low filter, high filter and muting circuit.
In addition, it is equipped with a continuous loudness circuit, and by providing a volume dedicated to the loudness, it is possible to compensate for the efficiency of the speaker, the size of the room and the volume of the volume based on the actual listener's ear.

Equipped with a pre-main coupler that can be used separately for the pre-amplifier and main amplifier.

Model Rating

Type	Pre-main amplifier
Main Amplifier Section
Circuit system	Class B and Class A operation switching type all stages directly connected pure complimentary service SEPPOCL circuit
Dynamic Power (IHF)	Class B operation : 130W (8 Ω)
Effective power	When both channels are operating 20 Hz to 20 kHz : 10W + 10W (8 Ω, Class A operation) 50W + 50W (4 Ω, Class B operation) 45W + 45W (8 Ω, Class B operation) 1kHz: 10W + 10W (8 Ω, Class A operation) 60W + 60W (4 Ω, Class B operation) 50W + 50W (8 Ω, Class B operation) Single-channel operation 1 kHz : 10W/10W (8 Ω, Class A operation) 70W/70W (4 Ω, Class B operation) 55W/55W (8 Ω, Class B operation)
Total harmonic distortion factor	Class A operation : 0.1% or Less (Effective Output) 0.02% or Less (at 1W output) Class B operation : 0.1% or Less (Effective Output) 0.04% or Less (at 1W output)
Cross modulation distortion factor (70Hz:7kHz=4:1)	Class A operation : 0.1% or Less (Effective Output) 0.05% or Less (at 1W Output) Class B operation : 0.1% or Less (Effective Output) 0.05% or Less (at 1W Output)
Power bandwidth (IHF, both channel drive)	Class A operation : 5 Hz to 100 kHz Class B operation : 5 Hz to 70 kHz
Frequency characteristic	10 Hz to 100 kHz + 0 -1dB
Input Sensitivity / Impedance	Class A operation : 345mV/40k Ω Class B operation : 775mV/40k Ω
Output terminal	Speaker jacks : 2 channels Headphone terminal : 4 Ω ~ 16 Ω
Damping factor	70 (1 kHz, 8 Ω)
Signal-to-noise ratio (IHF, A-network)	100dB
Residual noise	0.8 mv (pre + main amplifier)
Preamplifier Section
Circuit system	Equalizer amplifier : 4-stage direct connection NFB type amplifier Control Amplifier : Intermediate Emitter-Follower 3-Chip Connected Amplifier
Input Sensitivity / Impedance	Phono1 : 3mV/30k Ω, 50k Ω, 100k Ω Phono2 : 3mV/50k Ω MIC : 2.5mV/50k Ω Tuner, AUX1, 2, Tape PB A, B : 120mV/40k Ω
Output Level / Impedance	Rec outA, B : 120mV/2k Ω Pre out : 775mV/2k Ω
Phono maximum allowable input	310 mVrms (870mVp-p, 1 kHz, 0.1% distortion)
Frequency characteristic	Phono (RIAA deviation) : 30 Hz to 15 kHz ± 0.2 dB Tuner, AUX, Tape PB : 10 Hz to 50 kHz + 0.5 -1dB
Signal-to-noise ratio	Phono:80dB MIC:70dB Tuner, AUX, Tape PB : 90 dB
Tone control	Bass : ± 10 dB (50 Hz), Turnover Frequency : 250 Hz, 500 Hz Treble : ± 10 dB (10 kHz), Turnover Frequency : 2.5 kHz, 5 kHz
Filter	Low : 20Hz/70Hz, 12dB/oct. High : 6kHz/12kHz, 6dB/oct.
Loudness control	Continuous loudness corresponding to an equal loudness curve
Audio Muting	-20dB
<General>
Semiconductor used	Transistor : 49 FET : 2 Diode : 12 pcs Zener diode : 4 pcs
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	Rating : 190W Maximum : 300W
AC outlet	Power switch interlock : 2 systems, max200W Power switch not interlocked : 2 systems, max200W
External dimensions	Width 436x Height 144x Depth 323 mm
Weight	13.5kg