Accuphase C-2400 Brochure

m Revolutionary AAVA volume control for top performance and superb

sound quality m Fully modular construction with individual left/right
amplifier units arranged on motherboard m Separate power
transformers and filtering capacitors for left and right channels
m Logic-controlled relays for shortest signal paths m High quality
tone controls m Optional analog record playback capability

Innovative AAVA type volume control guarantees great sound and top
performance Experience volume adjustment without deterioration in
S/N ratio or distortion. AAVA and other circuit modules are arranged on
motherboard separately for left and right channels. Fully dual monaural
construction features two separate power transformers. Dedicated phono
equalizer unit allows analog record reproduction with superb fidelity.

The C-2400 inherits the design technology of the
outstanding Accuphase C-2800, featuring the
same AAVA type volume control. One of the most
important aspects of a preamplifier is how it
handles volume adjustment. AAVA (Accuphase
Analog Vari-gain Amplifier) is an innovative
concept that differs radically from conventional
variable-resistor type volume controls.
Amplification and volume control are fully unified,
eliminating all mechanical contact points. Pure
analog processing ensures optimum
performance and superb sound. Doing away with
the variable resistor in the signal path has
numerous advantages and brings the amplifier

a significant step closer to absolute purity in
signal transmission. Another benefit of AAVA is
that it is configured only with highly reliable
semiconductor components. This assures that
performance and sound quality will remain
undiminished for many years to come. The large
volume knob on the front panel employs a
position detection method that combines superb
precision with a smooth conventional feel.
The power transformer, filtering capacitors and
all other parts of the power supply are duplicated
for the left and right channel. What's more, all
unit amplifiers such as for line input, balanced
output, and AAVA are also entirely separate for

the two channels, arranged on a high-quality
motherboard. This fully monaural construction
prevents unwanted interaction both on the
electrical and the physical plane.
The line amplifier with integrated volume control
is a major aspect of the C-2400, but there are
also a host of other attractive features in this
superb analog preamplifier. Tone controls and
loudness compensator allow fine tuning of the
sound. Tape recorder and copying facilities as
well as an EXT PRE function provide connection
flexibility. A phono equalizer unit (AD-2800) for
faithful playback of analog records is also
available.

AAVA (Accuphase Analog Vari-gain Amplifier) volume control

The newly developed volume control called AAVA (Accuphase Analog Vari-gain Amplifier) is totally different from conventional controls using
resistors. Because the music signal does not pass through variable resistors, it is not affected by changes in impedance. This means that high
signal-to-noise ratio and low distortion of the signal are maintained. The volume can be adjusted without any deterioration in sound quality.

n AAVA resolution

AAVA adjusts the listening volume by means of 16 current
switches which are operated by 16 weighted V-I converter
amplifiers. The number of possible volume steps set by the
combination of these converter amplifiers is 2 to the power
of 16 = 65,536.

n AAVA maintains high S/N ratio

With conventional volume controls, the impedance
increases significantly at settings that correspond to normal
listening levels, thereby leading to increased noise. Because
AAVA performs adjustment by selective use of V-I converter
amplifiers (changing the actual gain), there is no change in
impedance and thus no deterioration of S/N ratio. Changing
the volume with AAVA does not mean introducing noise or
detracting from the high performance of the amplifier.

n No more left/right tracking differences or

crosstalk

Because AAVA is an electronic circuit employing highly
precise metal film resistors, there is virtually no left/right
tracking error also at low volume levels. Since channels
can be kept separate, crosstalk also does not present a
problem.

n Simple circuit configuration

AAVA unifies the amplifier and volume control functions,
resulting in a circuit that is electrically very simple. Long­term reliability is excellent, with performance and sound
quality that will remain unchanged also after prolonged use.

n AAVA means analog processing

The AAVA circuit converts the music signal from a voltage
into a current, switches gain by means of current switches,
and then reconverts the current into a voltage. The entire
process is carried out in the analog domain.

n Same operation feel as a conventional high-

quality volume control

The volume control knob position is detected by a dedicated
CPU which in turn selects the current switches for AAVA
operation. Operating the knob therefore feels exactly the
same as with a conventional control, and as before,
operation via the remote commander is also possible.

n Attenuator and balance control also

implemented by AAVA

The functions of the attenuator and the left/right balance
control are covered by the AAVA circuit as well, eliminating
the need for additional circuit stages. Keeping the
configuration simple helps to maintain high performance
and sonic purity.

BUFFER

INPUT

BUFFER

Input music signal

V- I Converter

Conversion into current with 16
weighting stages (1/2 - 1/216)

AAVA operates by feeding the music signal to a V-I (voltage - current) converting amplifier
where it is weighted in 16 steps [1/2, 1/2
off by 16 current switches, and the combination of switch settings determines the overall volume.
The switching operation is controlled by a CPU according to the position of the volume control
knob. The combined signal current forms a variable gain circuit that adjusts volume. Finally, the
combined current is converted back into a voltage by an I-V (current - voltage) converter.

16 current switches
(65,536 possible combinations)

Volume
Balance

CPU

Attenuator

CPU detects position of volume knob
and operates current on/off switches
according to knob position

AAVA operation principle

Current
values
are
added

AAVA operation principle

2

, ... 1/215, 1/216]. The 16 current steps are turned on or

Input buffer, 16 V-I converter
amps and current switches,
current adder, I-V converter
amp, and other circuitry on
modular AAVA unit, installed
separately for left/right
channel on motherboard

Reconversion of current into
voltage

I-V Converter

OUTPUT

GAIN

VOLUME

5

46

37

28

19

MIN MAX

Volume knob is turned and
position is detected