Accuphase E-260 User Manual
● Revolutionary AAVA volume control ● Output stage with high-power transistors in parallel
push-pull arrangement delivers high quality power: 90 watts x 2 into 8 ohms ● Instrumentation amplifier principle for power amplifier input stage allows fully balanced signal transmission
● Logic-control relays for shortest signal paths ● Strong power supply with massive
high-efficiency transformer and large filtering capacitors ● EXT PRE button allows separate
use of preamplifier and power amplifier sections ● Numeric indication of volume level
Integrated amplifier with AAVA volume control − Power amplifier section
AAVA is a radically different volume control principle that eliminates all variable resistors from the signal path and uses analog processing to provide top-notch performance and sound quality.
featuring high-power transistors in parallel push-pull configuration, together
with robust power supply, realizes low impedance in output stage. Rated for 90
watts of quality power into 8 ohms, with damping factor of 200. Current feedback
amplifier topology assures excellent phase characteristics in high range, and
instrumentation amplifier principle enables fully balanced signal transmission.
The Accuphase E-200 series of integrated
amplif iers occu pies a cent ral posit ion in
the Accuphase lineup, and enjoys enduring
popularity both in Japan and abroad.
The E-260 stands firmly in this tradition,
harnessing the technology advantages of the
series in a new format. It represents a major
overhaul of the E-250, reflecting latest design
technology and featuring the same advanced
AAVA volume control as the higher-ranked
models E-560, E-460, and E-360. The result
is a classy integrated amplifier that brings out
the full musical splendor of every source.
AAVA is a revolutionary principle that
redefines the concept of volume control from
the ground up, operating purely in the analog
domain for high performance and ultimate
sound. Starting with the ultimate, top-of-theline preamplifier C-3800, it has received high
praise as a crucial ingredient for sonic
excellence in preamplifiers and integrated
amplifiers.
The preamplifier and power amplifier sections
of the E-260 are separate circuits that rival
discrete components in performance and
sound. With a simple flick of the EXT PRE
switch, the preamplifier can be detached from
the power amplifier, allowing the sections to
be used individually.
The power amplifier block is configured as an
advanced instrumentation amplifier, which
enables fully balanced signal transmission
throughout. Together with the highly
acclaimed current feedback principle, this
makes for even better electrical characteristics. In the output stage, high-power audio
grade transistors are arranged in a parallel
push-pull configuration which significantly
enhances the capability to safely drive
low-impedance loads.
Output operation is sustained by the power
supply with a massive power transformer and
large filtering capacitors. This provides
high-quality power output of 115 watts x 2 into
4 ohms or 90 watts x 2 into 8 ohms, along
with a damping factor of 200, thanks to the
redesigned circuitry.
AAVA (Accuphase Analog Vari-gain Amplifier) Volume Control
Because the music signal is not affected by changes in impedance due to variable resistors, high signal-to-noise ratio and low distortion are maintained at any volume control setting.
■
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
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 error or crosstalk
Because AAVA is an electronic circuit employing fixed-value resistors, there are
virtually no left/right tracking differences even at very low volume levels. Since
channels can be kept separate, crosstalk also ceases to be a problem.
16 current switches
Input music signal
BUFFER
INPUT
5-MCS
1
2
1
2
2
1
3
2
1
15
2
1
16
2
(65,536 possible combinations)
AAVA configuration in E-260
I -V Converter
＋
Current
values are
added
Reconversion of
current into voltage
AAVA means analog processing
■
The AAVA circuit converts the music signal from a voltage into a current, controls
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
■
Operating the volume knob feels exactly the same as with a conventional control,
and as before, operation via the remote commander is also possible.
A
ttenuator 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).
AAVA operation principle
The music signal is converted into 16 types of
I - V
LEVEL DISPLAY
OUTPUT
weighted current by V-I (voltage - current)
converting amplifiers [1/2, 1/2
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.
2
, ... 1/215, 1/216].
V- I Converter
Conversion into current
with 16 weighting stages
16
)
(1/2 - 1/2
Volume
Balance
CPU
Attenuator
CPU detects position of volume knob
and operates current on/off switches
according to knob position
Volume knob is turned
and position is detected
■CPU assembly for control of AAVA
and various other functions
■AAVA volume control assembly
with higher integration density
of components and circuitry
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