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| Accuphase C-290V |
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| 980,000 yen(December, 1998 release) |
Control amplifier which adopted the current feedback magnification circuit,
raised the completeness of all the circuits further as a compilation of an
analog preamplifier based on the balance transmission technology established by
C-290, and aimed at the highest peak.
The current feedback type
magnification circuit which returns an output signal in the form of current is
adopted.
In this circuit, the impedance of the input terminal by the side of
a return was lowered, current was detected, I-V conversion of that current was
carried out with the transformer impedance amplifier, and the output signal is
made. Since the impedance of a return input portion is very low, it is hard to
generate phase rotation and there is almost no necessity for a phase guarantee.
For this reason, many characteristics have been sharply improved by a little
NFB(s), it excelled in dynamic characteristics, such as a standup, and the
natural energy response has been obtained also in respect of sound quality.
The balance output circuit of a bridge feedback system is carried.
Balance transmission is a system which sends simultaneously the
positive/negative symmetrical signal which the phase reversed mutually, and is
excellent in the capability to remove the noise ingredient in the common mode.
In C-290V, it has a relation of tucking up its sleeves with a cord which
feeds back each output of 2 sets of amplifier to the other party, and the
symmetrical signal of +- is sent out by low impedance. In this circuit, since
floating of the symmetrical signal of +- is carried out from the ground, even if
it grounds one side of an output, both of amplifier operates and an Output
voltage does not change.
A line amplifier part is a pure complimentary
push pull circuit, and constitutes this from a discrete part by a current
feedback magnification circuit. Thereby, phase compensation of each stage is
made light.
The printed circuit board by a Teflon base (woven glass
fabric fluoro-resin) is adopted as a signal transmission circuit.
This
material has the lowest relative dielectric constant and dielectric dissipation
factor, and heat resistance and the high frequency characteristic are excellent, and it is used for satellite broadcasting, a high precision measuring
instrument, etc. which mainly use a super-high-frequency belt.
The
propagation velocity of a signal becomes quick, so that the dielectric constant
of a printed circuit board is low, and path loss becomes small, so that a
dielectric dissipation factor is small. In C-290V, a golden plate is given to a
銅箔 side, and also improvement in sound quality is aimed at.
Right-and-left independence is achieved also with a power transformer
and a filter condenser, and it has monophonic composition completely
electrically. Furthermore, the broadband low impedance power source was carried
in all the unit amplifier, and the mutual intervention between amplifier is
prevented thoroughly.
The amorphous core which was excellent in the
frequency response is adopted as a power transformer. Amorphous (Amorphous)
serves as amorphous metal which is a synthetic thin strap obtained by
super-quenching a Molten metal, and does not have a crystal structure. For this
reason, the character which was excellent in magnetic and a machine target
compared with crystal structure metal was shown, and it has the characteristic
and the feature of having excelled as an object for audios.
Four ream volume in which CP (conductive plastic) element is adopted for
the resistance body is adopted in the volume.
When CP resistance object carries out high temperature
pressurization fabrication after printing a resistive element, the surface is
the low contact resistance and the element of a low distortion which were
finished in the shape of a specular surface.
A very thick brass shaft 8mm in diameter is supported by an aluminum cutting bearing, four children's element is stored in a high precision aluminum cutting case, respectively, a perfect shield is given, and improvement in sound quality is aimed at.
A variable system is
continuation good transformation, and a tracking error is a position of -60dB
and serves as survey of less than 0.5dB.
Since straight signal
transmission is constituted at the shortest, the logic relay control system has
been adopted.
The sealed type relay for communication industry is adopted as
the relay used for this, and contacts are a plated with gold and a crossbar twin
system, and have acquired low contact resistance and quantity durability.
The amplifier circuit consists of right-and-left a total of four unit
amplifier, such as line-in and a balance output, and carries the exclusive
power-source part in each.
In order to prevent that these unit amplifier
interferes, it has stored in thick aluminum housing.
In the RCA phono
jack, nine lines and a balance input carry three inputs. Moreover, the output is
equipped with six lines.
Balance control on either side has adopted the
Attenuator of the 1dB step changed to 0 to -6dB, and -infinity with a push
button on either side, respectively. It is displayed on the display of a panel
side.
In order to correspond also to playback of an analog record,
record playback is also supported by extending optional exclusive phone
equalizer unit AD-290V from the rear panel side.
The printed circuit board
by a Teflon base (woven glass fabric fluoro-resin) is adopted as the quality of
the material of a print board, and the influence of external is prevented by
storing in a strong aluminum case AD-290V.
Circuit composition consists of
all the circuit symmetrical type push pulls, and is equipped with the exclusive
input circuit which matched the cartridge of each MM/MC. It constitutes from an
FET element of high S/N at the time of MM input, and since MC receives a minute
signal by low impedance, it constitutes the difference input circuit by a low
noise element, and enables little reproduction of noise.
MC input impedance
can choose three kinds. Moreover, a profit can also choose each two MC/MM to
compensate for the output of a cartridge. These changes can be performed in
respect of the panel of C-290V.
It is possible for phone equalizer unit
AD-290 used by C-290 to be compatible, and to use it for C-290V.
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The analog disc characteristic shows the time
of AD-290V extension.
| Form |
Stereo control amplifier |
| Frequency response |
| Balanced, Unbalanced : |
3Hz-300kHz+0 -3.0 dB
20Hz-20kHz+0 -0.2
dB |
AD MM/36dB, MC
input:20Hz-20kHz±0.2dB
AD MM/30dB input:20Hz-20kHz±0.3dB |
| THD |
0.005% |
Input sensitivity/impedance
(An Output
power / 0.5V output) |
AD MM/30dB: 8.0mV/2.0mV/47kohm
AD
MM/36dB: 4.0mV/1.0mV/47kohm
AD MC/62dB: 0.2mV/0.05 mV/10ohm, 30ohm, a
100-ohm change
AD MC/68dB: 0.1mV/0.025 mV/10ohm, 30ohm, a 100-ohm change
Balanced: 252mV/63mV/40kohm
Unbalanced: 252mV/63mV/20kohm
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| An Output power/impedance |
Balanced, Unbalanced output:2V/50 ohm
Tape rec (at the time of AD input): 252mV/200 ohms |
| S/N, input conversion noise |
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Input short-circuit
and A-compensation |
EIA S/N
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| At the time of an Output power
S/N |
Input conversion noise
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| AD MM/30dB: |
94dB |
-136dBV |
86dB |
| AD MM/36dB: |
90dB |
-138dBV |
86dB |
| AD MC/62dB: |
80dB |
-154dBV |
85dB |
| AD MC/68dB: |
75dB |
-155dBV |
85dB |
| Balanced: |
111dB |
-123dBV |
95dB |
| Unbalanced |
111dB |
-123dBV |
95dB
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Maximum-except-take-off level
(Distortion 0.005%, 20Hz - 20kHz) |
Balanced, Unbalanced output:8.0V
Tape
rec:9.5V |
The AD maximum inlet pressure
(1kHz,
distortion 0.005%) |
MM(30dB/36dB) input:300mV/150mV
MC(62dB/68dB) input:7.5mV/3.75mV |
| Minimum load impedance |
Balanced, Unbalanced output: 600ohms
Tape rec: 10kohm |
| Gain |
Balanced, Unbalanced input -> Balanced,
Unbalanced output: 18dB
Unbalanced input -> Rec output: 0dB
AD
MM(30/36dB) input -> Balanced, Unbalanced output: 48/54dB
AD MM(30/36dB)
input -> Rec output: 30/36dB
AD MC(62/68dB) input -> Balanced,
Unbalanced output: 80/86dB
AD MC(62/68dB) input -> Rec output: 62/68dB
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Compensation
(Volume -30dB) |
1:+3dB(100Hz)
2: +8dB (100Hz), +6dB
(20kHz) |
| Subsonic Filter |
10Hz, -18 dB/oct |
| Attenuator |
-20dB |
| Power source |
AC100V, 50Hz/60Hz |
| Power consumption |
24W |
| The maximum Dimensions |
Width 469x height 160x depth of 405mm
At
the time of AD-290V extension: Depth of 414mm |
| Weight |
23.8kg
At the time of AD-290V extension:
24.8kg |
| Option |
Phone equalizer unit AD-290V (200,000yen) |
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