|270,000 yen(June, 1994 release)
The stereo preamplifier which attained simple-ization a design and in respect of
a circuit, and aimed at the preamplifier of a new time based on the original
balance transmission technology of an Accuphase by each element selected
carefully, and the engine performance and sound quality which kept being
The original balance transmission system is adopted
as line amplifier.
Balance transmission is a system which sends
simultaneously the positive/negative symmetrical signal which the phase reversed
mutually, and it excels in the capability to remove the noise ingredient in
C-250 consists of three differential amplifier fundamentally, and at the time of balance, from +-both the inputs of amplifier 1, a signal
enters, and is amplified, and then it is inputted into amplifier 2 and amplifier
3. This 2-set Mino amplifier has a relation of tucking up its sleeves with a
cord which feeds back each output to the other party, and sends out the
symmetrical signal of +- by low impedance.
This circuit is the ideal circuit
system to which floating of the symmetrical signal of +- was carried out from
the ground, even if it grounds one side of an output, both of amplifier carries
out differential, and an Output voltage does not change. For this reason, it is
that input and output only connect either to an earth line at the time of the
usual imbalanced connection.
The main circuits of C-250 consist of
right-and-left a total of six unit amplifier, such as line amplifier, balance
input-and-output amplifier, and balance output amplifier, and are arranged on
the mother board.
In order to prevent the mutual intervention of these unit
amplifier, each is surrounded by thick aluminum knockout material, and it has a
structure strong also against resonance by external vibration.
power-source part achieves right-and-left independence also with a power
transformer and a right-and-left filter capacitor, and has monophonic
composition completely electrically. Thereby, the cross talk between channels
was canceled and the mutual intervention between amplifier is prevented.
The small resistance object of the distortion is adopted especially as
the volume controller. This resistance object is finished in the shape of a
specular surface, and has become what was excellent in antiwear quality with low
The brush in contact with a resistance object is a
gilding many contact type, an external terminal and solid construction are used, a metal composition plane is abolished, and distortion by different-species
metal contacting is reduced.
Moreover, the rotary system has adopted not the
method that a brush rotates but the structure which fixes this and a resistance
object rotates, the internal point of contact decreases sharply, and becomes
unnecessary [ contact grease ], and its durability is improving.
adoption s The logic relay control system of the Accuphase original
which adopted the seal type relay containing nitrogen gas for communication
industry is in the input selector part.
This system and a change installed
the relay in the required place, and have controlled these electronically in the
logic circuit. The microprocessor has managed fine timing and there is no noise at the time of a change.
The amplifier only for headphone is carried and
consideration is carried out also to the sound quality of headphone.
output to a speaker can be cut by a switch and it can carry out variable [ of
the headphone output ] in main volume.
The remote control which controls
[ a change and ] the volume of input sauce is attached.
Making the input
selector into the relay change system, volume control has prevented the bad
influence to sound quality by considering it as combination with a small motor
with a clutch.
Although C-250 is the composition only for a line, it can respond also
to an analog record with an optional phone equalizer unit.
||Balanced/Unbalanced Input: 20Hz-20kHz+0
||0.005% (with all the input terminals)
|Input sensitivity/input impedance
Output power / output 0.5V)
|An Output power/Output load impedance
||Balanced/Unbalanced Output: 2.0V/50 ohm
Tape Rec (at the time of AD input): 252mV/200 ohms
|Input short-circuit, IEC-A compensation (at
the time of a rated input)
|Input conversion noise
short-circuit, IEC-A compensation)
|maximum-except-take-off level (0.005% of
Rec(at the time of AD input): 7.0V
|Minimum load impedance
||Balanced Output: 600ohms
Tape Rec: 10kohm
Input->Balanced/Unbalanced Output: 18dB
|Power supply voltage
||At usually, the time: Width 475x height 140x
depth of 401mm
At the time of AD-250 extension: Depth of 414mm
||At usually, the time: 13.8kg
At the time
of AD-250 extension: 13.9kg
||Exclusive phone equalizer unit AD-250 (\30,000)
|Attachment: Remote commander RC-10
|Remote control system
||Infrared pulse system
||direct-current3V Battery: UM-4(IEC name R03)
|The maximum Dimensions
||Width 66x height 175x depth of 20mm
||190g (Battery included)