■
Supplied remote commander RC-200
Allows volume adjustment and
input source switching.
■AAVA volume control assembly
with higher integration density
of components and circuitry
■
CPU assembly which controls AAVA and various other functions
AAVA operation principle
The music signal is converted into 16 types of weighted current by
V-I (voltage - current) converting amplifiers [1/2, 1/2
2
, ... 1/2
15
, 1/2
16
].
The 16 currents are turned on or 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 the volume. Finally, the combined
current is converted back into a voltage by an I-V (current - voltage)
converter.
AAVA is a radically different volume control principle that eliminates all variable resistors from the signal path and provides top-notch performance and sound quality.
Because the music signal is not affected by changes in impedance, high signal-to-noise ratio and low distortion are maintained at any volume control setting.
AAVA (Accuphase Analog Vari-gain Amplifier) Volume Control
AAVA configuration in E-460
16 current switches
(65,536 possible combinations)
CPU detects position of volume
knob and operates current on/off
switches according to knob position
Conversion into current with 16
weighting stages (1/2 - 1/2
16
)
Current values
are added
Input music signal
Reconversion of
current into voltage
Volume knob is turned
and position is detected
V- I Converter
#05
2
OUTPUT
INPUT
5-MCS
I -V Converter
6OLUME
"ALANCE
!TTENUATOR
＋
2
2
2
3
1
−
1
−
1
−
2
16
1
−
1
−
2
15
BUFFER
■
Volume control resolution
AAVA adjusts the listening volume by means of 16 weighted V-I converter amplifiers which are
controlled by current switches. The number of possible volume steps set by the combination of these
converter amplifiers is 2 to the power of 16 = 65,536.
■
Input buffer amps use 5-MCS topology
One of the factors that have a bearing on possible noise in an AAVA arrangement is the input buffer
design. By connecting five high-performance amps in parallel, excellent S/N ratio is assured.
■
AAVA maintains high S/N ratio and uniform frequency response
Unlike with conventional volume controls, AAVA does not introduce a change in impedance at any
volume setting. Consequently, there is no deterioration of S/N ratio, and frequency response remains
totally uniform. The benefits are especially apparent at settings that correspond to normal listening
levels, because the tonal quality is not altered in any way.
■
No more left/right tracking differences or crosstalk
Because AAVA is an electronic circuit employing fixed-value 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.
■
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.
■
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.
■
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.
■
Display shows volume level as numeric value
The volume level (degree of attenuation) as set with AAVA is shown as a numeric indication in the
center of the front panel. The indication ranges from MAX (0 dB) to MIN (lowest setting).
