m Pure Class A operation delivers quality power: 30 watts × 2 into 8 ohms m Power
MOS-FET output stage features 3-parallel push-pull configuration m Input section
configured as instrumentation amplifier m Further improved MCS+ circuit in amplifier
section m Current feedback topology combines stable operation with outstanding
sound m Bridged mode allows upgrading to monophonic amplifier m Strong power
supply with large power transformer and ample filtering capacity m 4-step gain control

Pure Class A sound that’s every audiophile’s dream — Input stage features fully balanced signal paths as found in high-quality instrumentation amplifiers.
Further refined MCS+ topology and current feedback result in superb soundquality and outstanding S/N ratio and other performance parameters. Strongpower supply section and power MOS-FET devices in triple-parallel pushpull configuration sustain linear power output progression down to ultra-low
impedances, with the capability to deliver 150 watts into 1 ohm (music signal).
A pure class A amplifier maintains a constant current flow
regardless of the presence or absence of a musical signal. This makes it possible to create a perfectly stablesound stage with unparalleled ambience that is the dreamof any audiophile. Within this rarefied breed of amplifiers,
the high-end pure class A stereo amplifier A-65 has garnered praise the world over as the ultimate reference forsuperb performance and sheer sonic excellence. The A-35
was developed as a successor to the A-30 while inheriting many design aspects of the A-65. Dedication to thebest sound possible is always an Accuphase hallmark.
The use of the instrumentation amplifier principle allows
fully balanced input signal paths, and further refined MCS+
topology pushes noise and distortion down to absolutely
minimal levels. In terms of its design as well as its sound,the A-35 offers a highly attractive entry point to the worldof pure class A.

n Triple push-pull arrangement of power MOS-FETs delivers 150 watts perchannel into 1 ohm (music signals), 120 watts into 2 ohms, 60 watts into
4 ohms, or 30 watts into 8 ohms.
n Strong power supply with large transformer and high filtering capacity.
The power supply features a large high-efficiency transformer and two 47,000 μF
aluminum electrolytic capacitors selected for sound quality.

n Instrumentation amplifier principle allows fully balanced signal paths, andcurrent feedback amplifier topology drastically improves S/N ratio.

Power transformern Bridged mode supports upgrading to monophonic amplifier with 300
watts into 2 ohms (music signals), 240 watts into 4 ohms, or 120 watts
into 8 ohms.
Simply by setting the mode selector to the bridged position, the A-35 is turned into amonophonic amplifier with 4 times the output power as compared to stereo operation.
This can be used when more power reserves are needed.
Filtering capacitors

In the output stage of the A-35, proven power MOS-FET
devices are used in a triple-parallel configuration for eachchannel. MOS-FETs have excellent frequency characteristics, and their high input impedance reduces the load
imposed on the preceding drive stage. The devices are
directly mounted on large heat sinks for efficient dissipation of thermal energy, assuring perfect operation stability. Driving these devices in pure class A produces rich,high-definition sound that brings out the finest nuances in
the music.

n Redesigned NFB circuit path results in minimized output
impedance, thereby further improving the damping factor.
This manifests itself in even better sound quality.

The power supply of an amplifier is its ultimate source ofenergy. Unless it provides ample reserves, sound quality
will suffer, and even basic performance parameters may
not be met. The A-35 has a massive power transformer
and two 47,000 μF smoothing capacitors specially selected for their sonic properties. This sustains an output power
rating of 120 watts into 2 ohms, 60 watts into 4 ohms, or
30 watts into 8 ohms per channel, and it enables the A-35
to perfectly handle even very-low impedance speakers orspeakers with wildly fluctuating impedance characteristics.
To prevent clipping on occasional momentary high-level
pulses, the maximum clipping level of the A-35 is set to 50
watts per channel into 8 ohms (sine wave output). Use inbridged mode is also possible, turning the A-35 into a highpower monophonic amplifier.

n Fully balanced input stage shuts out external noiseinterference.

n Analog power meters with off/sensitivity selector.
Meter illumination and operation as well as meter sensitivity (0 dB,–20 dB) can be controlled with a selector.

Meter selector

Gain selector

n 4-step gain control also minimizes residual noise.
The gain control switches gain in the first instrumentation amplifier
stage. Four settings are available: MAX, –3 dB, –6 dB, –12 dB.

n Mode selector with dual mono position supports bi-amping.
n Oversize speaker terminals accept also Y lugs.

Protection and power meter circuit assemblyHigh-reliability parts selected for sound quality

Unbalanced and balanced input connectors

Instrumentation amplifier

Large speaker terminals

NFB
NETWORKBiasstabilizer
REGULATOR

INPUT

SPEAKERTERMINALS

Bias
stabilizer
NFB
NETWORKGAIN CONTROLCIRCUITBias
stabilizer

OUTPUTBiasstabilizer

NFB
NETWORK

Output current (A)NFB
NETWORKINPUTREGULATOR
Biasstabilizer

Gain control

MCS+ (MultipleCircuit Summing)
Figure 1 Circuit diagram of amplifier section (one channel)

3-parallel push-pull
power MOS-FETs
Output voltage (V)1-ohm operation possible
with music signals only
Figure 2 Load impedance vs. output power(output voltage/output current)Instrumentation amplifier andfurther refined MCS+ topology
Instrumentation amp configuration allows
fully balanced signal paths
The newly adopted “instrumentation amplifier”
principle ensures that all signal paths from theinputs to the power amp stage are fully balanced.
This results in excellent CMRR (common moderejection ratio) and minimal distortion. Anothersignificant advantage is the fact that external noiseand other external influences are virtually shutout. The result is a power amplifier with drastically
improved operation stability and reliability.

Signal input stage

Power amplifier stage

INPUT

NFB
NETWORKGAIN CONTROLCIRCUITOUTPUTn Power amplifier assemblyPower amplifier assembly withthree parallel push-pull power MOS-FET
pairs per channel mounted directly to large heatsink, MCS+ circuitry, and current feedback amplifier.

Further refined MCS+ topology reduces
noise even furtherCurrent feedback principle assures excellent
phase characteristics in high range

Accuphase’s original MCS (Multiple CircuitSumming) principle uses a number of identicalcircuits connected in parallel to achieve superior
performance characteristics. MCS+ is a further
refined version of this approach. By extending
parallel operation to the class A drive stage ofthe current/voltage converter, the noise floor has
been further lowered.

As shown in the illustration, the A-35 uses theoutput signal current rather than voltage for
feedback. Since the impedance at the current
feedback point is very low, there is almost no phaseshift. A minimal amount of NFB therefore results inmaximum improvement of circuit parameters.

INPUT
BufferNFB
NETWORK

Current
adder

I/V
converterAmplifier

Trans-impedance amplifier
INPUT
BufferINPUTCurrent NFB
network

Instrumentation amplifier configuration

Principle of current feedback amplifier

OUTPUTn Using two A-35 units, bridged connection or bi-amping is possible. n Input signal to be connected to LEFT connector (BALANCED or UNBALANCED) on both units.

Connection example for bridged setup

Connection example for bi-amping setup

Left loudspeaker

Right loudspeaker

Left loudspeakerIn bridged mode, the A-35 becomes a monophonicamplifier with even higher power output.
✽In a bi-amped setup, the speaker units for the LOW
frequency range and HIGH frequency range are driven
by separate amplifiers for optimum sound quality.

speaker terminals of A-35 are not used.

✽ The speakers must have a built-in crossover networkand separate inputs for LOW and HIGH range.
LOW

RIGHT

LEFT

RIGHT

HIGH

LOW

HIGH

LEFT

A-35 forright channel

A-35 forleft channel

Preamplifier

Right loudspeaker

A-35 forright channel

A-35 forleft channel

Mode selector of A-35
set to BRIDGE on
both units

Mode selector of A-35
set to DUAL MONO on
both units

Preamplifiern Front Panel

GUARANTEED SPECIFICATIONS[Based on the EIA RS-490 test standard]m Rated Continuous Average Output Power (at 20–20,000 Hz)
Stereo use
150 W/ch1-ohm load ( )(both channels operating 120 W/ch
2-ohm loadsimultaneously)
60 W/ch4-ohm load
30 W/ch8-ohm load
Monophonic use(Bridge connection)

300 W
240 W
120 W

2-ohm load ( )4-ohm load
8-ohm loadNote: Load ratings marked ( ) apply only to operation with music signals.
m Total Harmonic Distortion
Stereo use(both channels operatingsimultaneously)
Monophonic use(Bridge connection)n Rear Panel

0.05%
0.03%

2-ohm load
4 to 16-ohm load

0.05%

4 to 16-ohm loadm IM Distortion

0.01%

m Frequency Characteristics

At rated continuous average output:
20 - 20,000 Hz +0, –0.2 dB
At 1 W output: 0.5 - 160,000 Hz +0, –3.0 dB

m Gain28.0 dB (when GAIN switch set to MAX)
(Same for both stereo and monophonic use)m GAIN Switch Settings

MAX, –3 dB, –6 dB, –12 dB

m Load Impedance

Stereo use:
Monophonic use:

2 to 16 ohms
4 to 16 ohms

For music signals only: 1-ohm (for stereo) and 2-ohm (mono)loads are also supported.
m Damping Factor

200

m Input Sensitivity (at 8-ohm load, with GAIN switch set to MAX)
Stereo use
0.57 V at rated continuous average output (30 W)
0.11 V at 1 W output
Monophonic use

A Input type indicator
UNBALANCED, BALANCED
B Left/Right-channel output power meters(indication in dB and %)C Bridge mode indicator
D Meter selector
OFF, 0 dB, –20 dB
E Power switch
F Input selector button
UNBALANCED, BALANCED
G Gain selector
MAX, –3 dB, –6 dB, –12 dB

H Unbalanced inputs
I Balanced inputs
a Ground b Inverted (–)
c Non-inverted (+)
J Mode selector
DUAL MONO, NORMAL, BRIDGEK Left/Right-channel speaker outputterminals
L AC power supply connector

1.14 V at rated continuous average output (120 W)
0.11 V at 1 W output

m Input Impedance

Balanced: 40 kilohms

m S/N (A-weighted)

111 dB when GAIN switch set to MAX
118 dB when GAIN switch set to –12 dB(At rated continuous average output)m Output Meters

Logarithmic compression type; illumination turn-off capability;
meter sensitivity switch (–20 dB);
–40 to +3 dB (indication in both dB and %)m Power Source

AC 120 V/230 V, 50/60 Hz(Voltage as indicated on rear panel)m Power Consumption

155 W (with no input)
270 W in accordance with IEC 60065

Unbalanced: 20 kilohms

m Maximum External Dimensions
Width 465 mm (18 5/16")
Height 170 mm (6 11/16")
Depth 425 mm (16 3/4")
m Mass22.8 kg (50.3 lbs) net
29.0 kg (64.0 lbs) in shipping carton

Remarks
This product is available in versions for 120/230 V AC. Make sure that the voltage shown on the rear panel matches the AC line voltage in your area.
The shape of the AC inlet and plug of the supplied power cord depends on the voltage rating and destination country.

Supplied accessory● AC power cordm

Specifications and design subject to change without notice for improvements.

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