Audio Database

The

Accuphase C-240
395,000 yen(September, 1978 release)

Description

Stereo control amplifier planned as an object for highest-class audio systems.
A panel layout is the individual thing which used the push switch extensively, and circuit composition constituted all the magnification stage symmetrical type push pull drives from a Class-A direct-current system, and supplies the highest-class thing also to the element which affects sound quality.

The panel face consists of four rotation knobs, one lever switch, and 57 push switches.
By electronic control, especially an input selector is a system which controls the relay in a circuit, and can be changed by feather touch.
The change of head amplifier uses the strong point of an electronic-control system, and according to the cartridge of DISC1 and DISC2, it is possible to make ON/OFF memorize for exclusive use, respectively, and it is raising operativity.
Moreover, in order to improve the push switch and relay contact resistance which influence sound quality and durability, all are considered as the composition of 2 circuit arrangement use.

To an output, the perfect symmetrical type push pull circuit is adopted as all the magnification stages of the amplifier only for headphone from the entrance of head amplifier. This circuit was excellent in the linearity and has obtained the distortion best by a little NFB. As a result, TIM distortion which is a factor of sound quality degradation is improved.
Each unit amplifier of all of head amplifier, equalizer amplifier, high-level amplifier, and headphone amplifier is made into direct-current system. The capacitor for direct-current cut of NF loop which needs large scale is removed, and also an input capacitor is removed, it has become an ICL system, and sound quality is improved.

With input differential push pull composition, RET (ring emitter transistor) specially developed as an object for small signals is adopted, and head amplifier contributes to improvement in sound quality. Furthermore, input conversion noise is low suppressed by making an Output load impedance low by the large current drive of an output stage, and setting up return partial-pressure resistance low.
Moreover, head amplifier is modularized, does not have this evening of humidity, either, and carries out stable operation also to a temperature change.

As for equalizer amplifier, all the future magnification stages consist of symmetrical type push pulls through the FET buffer of an input.
The output of the equalizer adopted RET for high frequency electric power magnification (ring emitter transistor), by Class-A large current drive, measured low Output-load-impedance-ization and has set up return partial-pressure resistance low. The input conversion noise level near ideal full limits has been obtained by using high gmFET for an input buffer simultaneously.

With high-level amplifier (flat amplifier), direct-current servo system (PAT, PEND) is adopted so that it may operate as direct-current amplifier also in the state where tone control is used, and direct-current drift is suppressed to the almost nil state.
It becomes unnecessary [ an output condenser ] with direct-current servo system, and there is no condenser for a direct-current cut from Tuner and an AUX terminal to an output.

The headphone amplifier which used the pure complimentary circuit is carried in the amplifier only for headphone.

What constituted the slide child on 18 brushes is adopted as volume, and conductive plastic elements of specular surface finishing are consisted of by the resistance object.
It is what really carried out the mall degree of the film-like resistance object which arranged conductor nature particles continuously to the insulator of thermosetting resin, and the surface forms the smooth and strong emulsion side.
Contact resistance serves as stable volume over 1/18, and ‚­ and the long period of time to pull theoretically by adoption of 18 slide children and a conductive plastic element.

An electromagnetism type cartridge serves as resonance of a vibration system, an inductance of a coil, and the characteristic that the peak produced in the quantity region for the wiring tray capacity etc.
Since the high region characteristic of such a cartridge is adjusted, high frequency trimming can be carried and it can carry out variable [ of between -8dB ] continuously at 20kHz from a flat state.
It is DISC1 and DISC2 exclusive use and can control according to each cartridge.

When 500Hz, 200Hz, and loud sound use a turnover (200Hz and 7kHz) at 2kHz and 7kHz in low-pitched sound, control of heavy low-pitched sound and the highest region is possible for the turnover change of tone control. A change is a step type of 2dB.

Hearing impression at the time of small volume is rectified, and the loudness Compensation switch which prepares energy balance is carried.
Three kinds of curves can be chosen according to the characteristic of a regeneration level or a listening room.

The practicality of a filter is thought as important and only the Subsonic Filter of 17Hz and 12dB is carried.
CR is added to the input element of high-level amplifier, and the active filter is formed.
In order not to add an active device for exclusive use, sound quality degradation does not occur, either.

Two-set connection is possible for a tape recorder, and mutual dubbing is possible for it, hearing other program sauce by independent Koppies Izzi.
Moreover, when cutting an unnecessary program, the ON-OFF switch of the convenient recording output is formed.
At the time of OFF, this switch has an effective power source of a tape recorder, also in order to prevent distortion generated since an input circuit becomes the load of a control center.

The Attenuator switch is carried in the time of discovering the start point of a record and a record chipping, and changing. The switch which changes a level is formed besides this and three kinds of -10dB attenuation levels of -20dB-30dB can be chosen.

The mode switch has prepared the Blend position other than Stereo, Rev, and Mono.
It is for using it, when the interval of a speaker is too large, or when reproducing the sauce which reproduces the program sauce which carries out a separation unnaturally, and a spread of right and left narrows in 10dB, and turns into a natural spread.

The canon output connector is carried in one of three outputs.

It is stored by the cabinet of the native wood rosewood.


Rear Headphone
Internal Equalizer
High-level

Rating of a mode
Form Stereo control center
Frequency response High-level input: It is +0 20Hz - 20000Hz. -0.2 dB
Disc input: 20Hz-20000Hz}0.2dB
THD 0.005% (for 20Hz - 20kHz, Output power)
Input sensitivity/input impedance DISC1, 2 (Head Amp OFF):2.0mV/100 ohm, 47kohm, 82kohm, a 150kohm change
DISC1, 2 (Head Amp ON):0.1mV/100ohm fixation
Tuner, AUX, Tape Play1, 2:126mV/50kohm
An Output power/Output load impedance
(Volume maximum, the rated input)
Output: 2.0V/2 ohm
Tape Rec1, 2:126mV/500 ohms
Headphone Output load impedance: 0.3ohm
Output (8ohm load): 0.25W, 1kHz, 0.01% of distortion
Maximum-except-take-off level (for 20Hz - 20kHz) More than 10V, 0.005% of distortion
The disc maximum input Head Amp OFF: 400mVrms, 1kHz, 0.005% of distortion
Head Amp ON: 20mVrms, 1kHz, 0.005% of distortion
Minimum load impedance Outputs: 1kohm
Tape Rec: 10kohm
Gain
Tuner, AUX, and Tape Play
Tape Rec: 0dB
Outputs: 24dB
HeadPhones: 20dB
DISC (Head Amp OFF)
Tape Rec: 36dB
Outputs: 60dB
HeadPhones: 56dB
(It is +26dB at the time of the DISC input HEAD AMP ON)
S/N / Input conversion noise
(at the time of input short-circuit, IHF-A, and a rated input)
High-level input: 110dB / -128dBV
Disc input (Head Amp OFF): 85dB / -139dBV
Disc input (Head Amp ON): 72dB / -152dBV
Tone control The change type by 8 step push switch
Low-pitched sound 500Hz : }8dB (50Hz)
200Hz : }8dB (20Hz)
2dB step
2dB step
Loud sound 2kHz : }8dB (20kHz)
7kHz : }8dB (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)
Disc height rimming DISC1, DISC2, 0dB - -8dB continuation variable (with 20kHz)
Attenuator - A 10dB -20dB-30dB change type
Subsonic Filter 17Hz, 12 dB/oct
The semiconductor used 159Tr, 10FET, 102Di
Power source 100V, 117V, 220V, 240V, 50/60Hz
Power consumption 80W
Dimensions Width 466x height 188x depth of 391mm
Weight 18kg