YAMAHA CA-700

Commentary

A stereo pre-main amplifier with a rich input / output circuit and a generous circuit design.

All stages are directly connected and quasi complimentary service OCL circuit is adopted for the main amplifier.
The interstage condenser has been removed so that sufficient NF can be applied even at low frequencies, enabling amplification over a wide range of frequencies up to ultra-high frequencies.

There are two Phono circuits and two pairs of equalizer amplifiers for each application.
The Phono1 equalizer amplifier is for use in MM and IM cartridges with high voltage outputs. It is a 3-element amplifier with SRPP outputs. It has a wide dynamic range, is highly stable under the influence of Dainyu, and has improved SN and distortion factor.
The Phono2 equalizer amplifier is exclusively for MC-type cartridges with low output voltage. It can be directly connected to MC-type cartridges without using a step-up transformer. The circuit structure is a 4-chip amplifier with high gain and high SN using the base-grounded system effectively.

A protective circuit is mounted on the power transistor stage and speaker output circuit.
It uses SCR and TRIAC to guarantee accurate operation, preventing troubles caused by excessive input or short circuit of output terminal, and protecting power transistor and speaker from damage.

The tone control circuit uses the NF-type Yamaha system with a 2-stage direct amplifier.
By applying NF between the collector and emitter of the direct-coupled amplifier, the waviness at the middle point of the knob is within ± 0.5 dB.
In addition, NF can be sufficiently applied to realize a low distortion factor, and residual noise is minimized by the specification of a low-noise transistor and the design considering noise.

It is equipped with functions such as low filter, high filter and audio muting.

It is equipped with a monaural output terminal that combines and outputs the signals of the right and left channels of the preamplifier.
It also has a coupler switch that can be used to separate the preamp and main amplifier.

Model Rating

Type	Pre-main amplifier
Main Amplifier Section
Dynamic Power (IHF)	150W
Effective output (1 kHz)	Single-channel Drive : 60W/60W Both channel drive : 50W + 50W
Total harmonic distortion factor	0.05% (at 50W output)
Intermodulation distortion factor (70 hz : 7 khz = 4 : 1)	0.1% (at 50W output)
Power bandwidth (IHF)	10 Hz to 50 kHz
Frequency characteristic	15 Hz ~ 50 kHz + 0 -3dB
Input Sensitivity / Impedance	775mV/50k Ω
Output terminal	Speaker jacks : 2 channels Headphone terminal : 4 Ω ~ 16 Ω
Damping factor (1 kHz, 8 Ω)	50
Signal-to-noise ratio (IHF, A-network)	95dB
Residual noise (pre + main amplifier)	0.6mV
Preamplifier Section
Input Sensitivity / Impedance	Phono1 : 3mV/50k Ω Phono2 : 100 μ V/100 Ω Tuner, AUX1, 2, Tape PB A, B : 200mV/50k Ω
Output Level / Impedance	Rec Out (Pin) : 200mV/10k Ω Rec Out (Din) : 30mV/80k Ω Pre Out : 775mV/10k Ω Mono Out : 775mV/500 Ω
Frequency characteristic	Phono (RIAA deviation) : 30 Hz to 15 kHz ± 0.5 dB Tuner, AUX, Tape : 20 Hz to 30 kHz + 1 -3dB
Signal-to-noise ratio	Phono1:65dB Phono2:45dB MIC:55dB Tuner, AUX, Tape : 85 dB
Tone control	Bass : ± 10 dB (70 Hz) Treble : ± 10 dB (10 kHz)
Filter	Low : 70 Hz, 12dB/oct. High : 7 kHz, 12dB/oct.
Loudness control	70Hz:+8dB 10kHz:+6dB
<General>
Semiconductor used	Transistor : 36 FET : 2 Diode : 16 pcs Triac : 3 Thyristors : 2
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption (Electrical Appliance and Material Control Law)	250W
AC outlet	Power switch interlock : 2 systems Power switch not linked : 1 system max250W
External dimensions	Width 400x Height 140x Depth 300 mm
Weight	10.0kg