|1,100,000 yen(July, 2002 release)
Control amplifier which aimed at the highest peak by the engine performance
which carries AAVA system volume control as a compilation of an analog
preamplifier while raising the completeness of all the circuits further, repeats
examination and an audition of part each, and kept being polished to the limit, and sound quality.
The newly developed AAVA (Accuphase Analog Vari-gain
Amplifier) system volume control is carried.
This is a volume control system
of the completely new concept which does not use a variable resistor object,
changes a music signal into voltage -> current, changes current with a
switch, controls a gain, and has analog structure again changed into current
The principle of operation
has changed the music signal into "1/2, 1/22, ..., 1/215, 1/216", and 16 kinds
of current by which dignity attachment was carried out with the V-I transducer.
16 kinds of this current is turned on and off with 16 current switches,
respectively, and volume is decided by that combination. By CPU (micro
computer), switching control is controlled so that a knob position and volume
become the same. Composition of these current serves as Variable Gain Circuit
(volume control circuit) which changes the magnitude of a music signal, and also
the current compounded in the final stage is returned to voltage with an I-V
AAVA carries out variable [ of the volume ] by the change of 16
current switches. If 65,536 steps of 16th power = combination of 2 of 16
switches becomes possible and the maximum except take-off makes it 5V, they have
the resolving power of a 0.07mV minute signal.
Since there is no generating
of the thermal noise from a resistance object in order that a music signal may
not pass a variable resistor object, since electronic, and also a music signal
is not influenced by impedance, AAVA has the feature that the signal to noise
ratio does not change even if it changes volume. Furthermore, there is no
distorted influence constitutionally and a super-low distortion is obtained.
Since actual volume operation used the conventional variable resistor and
has detected the absolute value for volume in the knob position, it has obtained
the conventionally same feeling of operation as volume.
circuit of C-2800 consists of right-and-left a total of 18 unit amplifier, such
as an input buffer, AAVA, and a balance output, and each unit amplifier is
arranged with right-and-left independent composition on the mother board of
The framework structure by the hard aluminum of 8mm thickness
is firmly fixed so that a mutual intervention may not be carried out, and these
unit amplifier has prevented electric interference and mechanical vibration.
In order to avoid leading about of a signal course, a logic relay
control signal electronic switch is adopted, and the straight signal course is
constituted at the shortest.
Newly developed R-toroidal transformer is
adopted as a power-source part, and it has at it monophonic composition which
made right and left become independent with a filter condenser.
cross-sectional form is using the circle-shaped core, and R toroidal transformer
reduces a magnetic loss and raises efficiency, most leakage flux is lost.
Moreover, the exterior uses glass fiber for core material, and has a double case
of resin material with high intensity, and 3-fold structure by the epoxy high
filler material of vibration proof and adhesion nature.
circuit board by a Teflon base (woven glass fabric fluoro-resin base) is adopted
as a signal transmission circuit.
A Teflon base has the lowest relative dielectric constant and dielectric
dissipation factor, and is excellent in the high frequency characteristic,
and has the feature that heat resistance is also good. In C-2800, a golden
plate is further given to a Copper foil
side, and also improvement in sound quality is aimed at.
The gain of a preamplifier
part can be chosen by a three-stage.
Sound quality is thought as
important and headphone amplifier for exclusive use is built in.
PRE function in which a change in an external preamplifier is possible is
A Compensation, a phase change function, a function of an Attenuator, a
Subsonic Filter, etc. which are compensated with the shortage of massive
of low-pitched sound and loud sound are carried.
It is dedicated
by the wood case of persimmon finishing.
There is a phone equalizer unit
for exclusive use as an option, and it can respond also to playback of an analog
record by extending to the rear panel side.
AD-2800 has adopted the Teflon
base (woven glass fabric fluoro-resin base), and the influence from the outside
is reduced by storing in a strong aluminum case.
Moreover, the magnification
circuit was connected with the input terminal by the curtate distance, the
signal to noise ratio is improved, and the connector of a reliable DIN standard
is adopted as connection with a main part.
It is possible for it to be
compatible with C-290, phone equalizer unit AD-290 which were used by C-290V, and AD-290V, and to use it for C-2800.
Moreover, AD-2800 can be used also
for C-290 and C-290V.
The analog disc characteristic shows the time
of AD-2800 extension.
||Stereo control amplifier
AD MM/36dB, MC
|Balanced, Unbalanced :
||3Hz-200kHz+0 -3.0 dB
AD MM/30dB input:20Hz-20kHz±0.3dB
power / 0.5V output)
|AD MM/30dB: 8.0mV/2.0mV/47kohm
AD MC/62dB: 0.2mV/0.05 mV/10ohm, 30ohm, a
AD MC/68dB: 0.1mV/0.025 mV/10ohm, 30ohm, a 100-ohm change
|An Output power/impedance
||Balanced, Unbalanced output:2V/50 ohm
Rec (at the time of AD input): 252mV/200 ohms
|S/N, input conversion noise
|At the time of an Output power
||Input conversion noise
||Balanced, Unbalanced output:7.0V
the time of AD input): 6.0V
|The Line maximum inlet pressure
||Balanced, Unbalanced input:6.0V
|The AD maximum inlet pressure
|Minimum load impedance
||Balanced, Unbalanced output: 600ohms
(Gain switch 18dB position)
|Balanced, Unbalanced input -> Balanced,
Unbalanced output: 18dB
Unbalanced input -> Rec output: 0dB
MM(30/36dB) input -> Balanced, Unbalanced output: 48/54dB
input -> Rec output: 30/36dB
AD MC(60/66dB) input -> Balanced,
Unbalanced output: 80/86dB
AD MC(60/66dB) input -> Rec output: 62/68dB
* 12 / 18/24dB change is possible for a gain switch.
2: +8dB (100Hz), +6dB
||10Hz, -18 dB/oct
|The maximum Dimensions
||Width 477x height 156x depth of 412mm
the time of AD-2800 extension: Depth of 414mm
At the time of AD-2800 extension:
||Remote commander RC-32
AC power cord
An audio cable with a plug (1m)
||Phone equalizer unit AD-2800 (200,000yen)