Audio Database

The

Accuphase C-230
170,000 yen(May, 1979 release)

Description

Control amplifier which concentrated and completed the technology which the Accuphase has cultivated for years.
The head amplifier for MC cartridges and full-scale headphone amplifier are built in, and the tone control function is also carried abundantly.

The perfect symmetrical type push pull circuit is adopted as all the magnification stages which also include headphone amplifier from the entrance of head amplifier to the last output stage.
Moreover, the condenser for direct-current cut was removed from NF loop of all the unit amplifier, it was considered as direct-current system, and coloring on sound quality is eliminated. Furthermore, the condenser of an input is removed and it is considered as the ICL system.

MOS FET was adopted as the output stage of equalizer amplifier and high-level amplifier, and many characteristics are improved.

In order to prevent the rise of power-source impedance, the constant-voltage power source for exclusive use was prepared in the print circuit board of each unit amplifier, respectively, and the stability and many characteristics of having changed into the state and having excelled in the ideal power source and the power source have been acquired.

direct-current servo system is adopted and direct-current drift is suppressed to the almost nil state so that it may work as direct-current amplifier also in the state of having carried out tone control and having.
Since the feature of this servo system has controlled the constant current load of an input buffer and has not controlled directly the system into which a signal flows, it can be suppressing the influence which a servo system has on sound quality to the minimum.
Moreover, in order to solve that the distorted characteristic of a high region gets worse with the return capacity of an input buffer circuit, the prevention circuit from a return is inserted.

MOS FET is adopted as an output, by Class-A large current drive, an Output load impedance is lowered to equalizer amplifier, low impedance-ization of NF loop is simultaneously measured in it, and S/N is improved in it. the high region according to the return capacity of an input circuit also to this amplifier -- the prevention circuit from a return which prevents distorted aggravation is inserted.

In order that transparency may reproduce a high richer detail in the head amplifier constituted from a symmetrical type push pull circuit, the input has been carried out to direct connection.
And to the noise which poses a problem since the signal level is small, the super-low noise transistor was adopted and S/N near ideal full limits has been obtained.

The amplifier only for direct-current composition Class-A pure contest direct connection is adopted as headphone amplifier.

Expansion of the tone control function was measured and the turnover changeover switch is prepared.
Thereby, 2kHz and 7kHz can be chosen by 200Hz, 500Hz, and TREBLE by BASS.
11 contact rotary switch performs and the variable method can keep change of a step exact.
Moreover, the tone control ON/OFF switch is also carried.

Hearing impression at the time of the amount reproduction of low-pitched sound was rectified, and the loudness Compensation switch which prepares energy balance is formed. Three kinds of curves can be chosen according to the characteristic of a regeneration level or a listening room.
As for COMP1, +9dB (50Hz) and COMP3 are +10dB (50Hz) and +6dB (20kHz) +6dB (50Hz) and COMP2. (All are volume control-30dB)

The Subsonic Filter of 17Hz and 12 dB/oct is carried.
The sound quality at the time of ON is thought as important, the input active device of high level amplifier is utilized, and the active filter is formed only by the addition of CR, without adding an active device.
This is suppressing sound quality degradation and S/N degradation.

Two-set connection is possible for a tape recorder etc., and mutual dubbing is possible for it, hearing other program sauce with the independent copy switch.
Moreover, when cutting an unnecessary program, the ON/OFF switch of the convenient recording output is formed. When the power source of a tape recorder etc. is OFF, this switch is useful also in order to prevent distortion generated since an input circuit becomes the load of control amplifier.

When not using an Attenuator switch of -20dB useful when discovering the start point of a record, a mode switch, and a tape recorder, a recording output circuit is cut, and the function of the switch which prevents distorted generating is carried.

There is a cabinet of natural rosewood finishing as an option.
(It is the cabinet reflected with the photograph)


The A
Pure
Head

Rating of a mode
Form Stereo control center
Frequency response (new IHF) High-level input: It is +0 20Hz - 20000Hz. -0.2 dB
Disc input: 20Hz-20000Hz±0.2dB
THD (new IHF, THD+N) 0.005% or less (20Hz - 20000Hz)
Input sensitivity/input impedance
(Rating / new IHF)
DISC(HEAD AMP:OFF): 2.5mV/0.96mV/100, 47k and 82k, 150kohm
DISC (HEAD AMP:ON): 0.125mV/0.05 mV/100 ohms
AUX, Tuner, Tape, and Play:160mV/62mV/47kohm
An Output power/Output load impedance Output: 1.3V/20 ohm
Tape Rec: 160mV/200 ohms
Headphone Output load impedance: 0.3ohm
Output (8ohm load): 0.25W, 1kHz
Distortion (THD+N): 0.01%
S/N (A-compensation) / input conversion noise
It is input short-circuit at the time of a rated input.
Tuner, AUX, Tape Play : 112dB -128dBV
DISC(HEAD AMP OFF): 87dB -139dBV
DISC(HEAD AMP ON): 74dB -152dBV
New IHF
Tuner, AUX, Tape Play : 92dB
DISC(HEAD AMP OFF): 85dB
DISC(HEAD AMP ON): 76dB
Maximum-except-take-off level More than 8.0V
Distortion (THD+N): 0.005% (20Hz - 20000Hz)
The disc maximum input
HEAD AMP OFF: 300mVrms, 1kHz
Distortion (THD+N): 0.005%
HEAD AMP ON: 15mVrms, 1kHz
Distortion (THD+N): 0.005%
Minimum load impedance Outputs: 1kohm
Tape Rec: 10kohm
Gain
Tuner, AUX, and Tape Play
Tape Rec: 0dB
Outputs: 18dB
HeadPhones: 18dB
DISC (HEAD AMP OFF)
Tape Rec: 36dB
Outputs: 54dB
HeadPhones: 54dB
(It is +26dB at the time of the DISC input HEAD AMP ON)
Tone control The step type by 11 contact rotary switch
Low-pitched sound 500Hz : ±10dB (100Hz)
200Hz : ±10dB (50Hz)
2dB step
2dB step
Loud sound 2kHz : ±10dB (10kHz)
7kHz : ±10dB (50kHz)
2dB step
2dB step
Loudness Compensation COMP1:+6dB(50Hz)
COMP2:+9dB(50Hz)
COMP of 3:+10dB (50Hz), +6dB (20kHz)
(with Volume control and -30dB)
Subsonic Filter 17Hz, -12 dB/oct
Attenuator -20dB
The semiconductor used 85Tr, 16FET, 5IC, 22Di
Power source 100V, 117V, 220V, 240V/50Hz, 60Hz
Power consumption 35W
Dimensions the width 445x height 128(piece -- it includeds) x depth of 370mm
Weight 10.0kg
Option Wood cabinet A-9 (15,000yen)