Accuphase C 220 Студия VintageAudio

Accuphase C-220
￥220,000 (Released in June 1977)
A disc control amplifier developed as a pre-amplifier for records only.
Since it is a recording player, there is no auxiliary terminal or tape input terminal. Instead, there is a terminal that is directly connected to the power amplifier when the power switch of the C-220 is turned off. Using this, you can connect a tuner or tape recorder to the control amplifier you already own, and the output of the amplifier is connected to the C-220 EXT. Preamp. By connecting to Input, you can automatically connect the output of the control amplifier you already own to the power amplifier.
Also, when correcting frequency characteristics with tone control, C-220 Fixed You can use it as an equalizer amplifier by taking the signal from the Output and connecting it to the aux input of an existing control amplifier.
The head amplifier for the MC cartridge is built in, and the gain is 26 dB for the head amplifier and 60 dB from the equalizer to the output.
In addition, the head amplifier is switched by relay control so that MC and MM can be selectively used with one arm, and shock noise is eliminated by having a time difference with the output muting relay by electronic circuit.
We use carefully selected relays with low contact resistance and excellent long-term durability.
The circuit configuration is based on the full-stage symmetric push-pull circuit developed for P-300 and C-200 and has been further improved.
Since this circuit has excellent element characteristics before applying NFB, low distortion factor can be expected as a result. In addition, this circuit is robust against power supply voltage fluctuations and can operate stably.
Each unit amplifier including the head amplifier is a class A drive, and is configured as a DC amplifier without NF loop condenser.
The head section of the head amplifier consists of a symmetric push-pull differential amplifier using four RET (Ring-Emitter Transistor), which was developed for high-frequency power amplification, and a class A DC-amplifier with pure complimentary service.
The RET consists of 100 small-signal transistor units combined in parallel via the ballast resistance of the emitter through the diffusion layer. This enables power amplification while maintaining the high-frequency characteristics of the small-signal transistor. This RET is used at the inlet of the head amplifier with the lowest signal level to achieve a significant reduction in noise level. Furthermore, by passing a large current through the amplifying element, the impedance of the circuit is reduced, the impedance of the NFB input side of the differential amplifier is lowered, and noise generated by the circuit is greatly reduced.
The input conversion noise of the head amplifier is measured as -154dBV (rated input 0.1 mV, S/N74dB), and excellent characteristics are realized.
The input of the equalizer amplifier section is a direct input circuit by combining a differential amplifier circuit with an FET buffer.
In addition, a RET with excellent high-frequency characteristics is connected to the pure complimentary service to lower the impedance of the NF loop.
.
As a result, the measured input equivalent noise of the equalizer amplifier is -140dBV (rated input 2 mV, S/N86dB).
The power supply is stabilized by a DC servo amplifier to keep the impedance of each frequency as low as possible from DC to ultra-high frequency.
The output includes a Canon connector output as well as a normal RCA pin jack.
As with the F-5 Multi-Channel Divider, there are 2 types of designs, A type of 19-inch rack mount type and B type of side plate.

[@Mr.O2183]

Nice