m Pure Class A operation delivers quality power: 60 watts × 2 into 8 ohms m Power MOS-FET
output stage features 10-parallel push-pull configuration and delivers linear high power progression
to ultra-low 1-ohm impedances 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 Two
selectable meter types: digital power meters showing true power values and bar graph indicators

Pure Class A power amplifier with power MOS-FET devices — Input stage features fully balanced signal paths as found in high-quality instrumentation amplifiers. Further
refined MCS+ topology and current feedback result in superb sound quality and outstanding performance parameters. Strong power supply section and power MOS-FET
devices in ten-parallel push-pull configuration sustain linear power output progression
down to impedances as low as 1 ohm. Digital power meters show true power readings.
The combination of pure class A and power MOS-FET
devices to realize high output power with excellent sonicpurity is a domain where Accuphase excels. Models suchas the A-100, A-50V, and A-60 have achieved legendary
status among audiophiles and represent an unrivaled levelof technological excellence. As a model-change successor
to the A-60, the new A-65 incorporates accumulated Accuphase know-how while featuring a number of further improvements. The input stage is configured as an instrumentation amplifier to allow fully balanced input signal paths.
The further refined MCS+ topology pushes noise and distortion down to absolutely minimal levels, and strictly selected materials and parts of the highest quality are usedthroughout. The end result is a high-end class A stereo amplifier with simply stunning performance and sound quality.

n Power modules with 10-parallel push-pull arrangement of power MOS-FETsdeliver 480 watts per channel into 1 ohm (music signals), 240 watts into 2ohms, 120 watts into 4 ohms, or 60 watts into 8 ohms.
n Strong power supply with high-efficiency toroidal transformer and two
extra-large 82,000 μF filtering capacitors.
n Bridged mode supports upgrading to monophonic amplifier with 960 watts
into 2 ohms (music signals), 480 watts into 4 ohms, or 240 watts into 8ohms.
n Instrumentation amplifier principle allows fully balanced signal paths, andcurrent feedback amplifier topology drastically improves S/N ratio.
n Four gain control settings (MAX, –3 dB, –6 dB, –12 dB) minimize residualnoise.
n Fully balanced input stage shuts out external noise interference.

The output stage of the A-65 features power MOS-FETs
renowned for their excellent sound and superior reliability.
For each channel, ten of these devices are arranged in aparallel push-pull arrangement. MOS-FETs have excellent
frequency characteristics, and their high input impedance
reduces the load imposed on the preceding drive stage.
They also have negative thermal characteristics, which
ensures perfect operation stability. Driving these devices
in pure class A produces rich, high-definition sound thatbrings out the finest nuances in the music. In a pure class A
amplifier, the power provided by the power supply is always
constant, regardless of the presence of a musical signal.
This means that the amplifier remains unaffected by fluctuations in voltage and other external influences.
On the other hand, it also means that the output stage
generates considerable thermal energy. In the A-65, thisis dissipated effectively by large heat sinks which
provide ample capacity to remove the heat produced by the internal circuitry. The high-efficiency
toroidal power transformer housed in an aluminum diecast enclosure, in conjunction with amply
dimensioned smoothing capacitors, provides themuscle to deliver an astonishing 480 watts perchannel into a 1-ohm load (music signals only). If
even higher power reserves are required, bridged
mode turns the A-65 into a superlative monophonic power amplifier.

Toroidal power transformern Dual mode power meters, switchable to 5-digit numeric readout or 25-point
LED bar graph indication.
● Meter circuit ON/OFF switch.
● Digital power meters show true
output power values, based on
output current detected by aHall element.
● Peak value hold time settings: 1 second,

Filtering capacitors

Hall element.

n Input selector button (balanced/unbalanced) on frontpanel.
n Mode selector with dual mono position supports biamping.
n Oversize speaker terminals accept also Y lugs.

Gain selector

Mode selector

Large speaker terminals Unbalanced and balanced input connectors

Meter circuitry/control circuitry assembly

Instrumentation amplifier+ B1

REGULATOR
Bias stabilizer
circuit+ B325

Q1Q5

Q910-parallel push-pull
power MOS-FET array

Q 19

Q 13547W+ B220+-Q3

NFB
NETWORK

Q7

Q 11

Q 21

Q 23

Q 25

Q 27

Q 29

Q 31

Q 33

Q 35

Q 37

Q 39

Q 41

Q 1515Bias stabilizer
circuit365W

NFB
NETWORKGAIN
CONTROLOUTPUT

Output current (A)+ INPUTQ 17

Bias stabilizer
circuit

Bias stabilizer
circuitNFB
NETWORKQ2- INPUT

+Q6

Q 10

Q 14

Q8

Q 12

Q 16

Q 18

Q 24

Q 26

Q 28

Q 30

Q 32

Q 34

Q 36

Q 38

Q 40

Q 42

214W

5118W

Q4- B3- B261W

Q 22

0Bias stabilizer
circuit
REGULATOR

Gain control

Q 201051015202530

35

Output voltage (V)- B11-ohm operation pwith music signals

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

0Power MOS-FETs

Figure 2 Load impedance vs. output(output voltage/output currInstrumentation amplifier and further 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.
Signal input stage+ INPUTThis results in excellent CMRR (Common Mode
Rejection Ratio) and minimal distortion. Anothersignificant advantage is the fact that external noiseand other external influences are virtually shut out.
The result is a drastic improvement in operationstability and reliability.

the current/voltage converter, the noise floor has
been lowered further.

Power amplifier stage

Further refined MCS+ topology for evenlower noise+

NFB
NETWORK+-GAIN CONTROLCIRCUITNFBNETWORK- INPUT+

Instrumentation amplifier configurationn Power amplifier assemblyPower amplifier assembly with
10-parallel push-pull power MOSFET pairs per channel mounted
directly to large heat sink, MCS+
circuitry, and current feedbackamplifier.

OUTPUT

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 ofCurrent feedback principle assures excellent
phase characteristics in high range
As shown in the illustration, the A-65 uses theoutput signal current rather than voltage for
feedback. Since the impedance at the current
feedback point is very low, there is almost nophase shift. A minimal amount of NFB therefore
results in maximum improvement of circuit
parameters.

- INPUT

BufferCurrent
adder

I/V
converter

Amplifier

OUTPUT

Trans-impedance amplifier+ INPUT

BufferCurrent NFB
network

Principle of current feedback amplifier

4045ossible
s onlyt powerent)

n Using two A-65 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 loudspeakerRight loudspeaker

Left loudspeakerIn bridged mode, the A-65 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-65 are not used.

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

LEFT

RIGHT

A-65
for rightchannel

Mode selectorof A-65 (set toBRIDGE onboth units)

HIGH

LOW

HIGHLEFT

A-65
for leftchannelL

Right loudspeaker

A-65
for leftchannelA-65
for rightchannel
LR

Preamplifier

When BRIDGE position is selected, thisindication appears onfront panel of A-65 for
3 seconds at power-on

Mode selectorof A-65 (set toDUAL MONO
on both units)

n Front PanelR

Preamplifier

GUARANTEED SPECIFICATIONS[Guaranteed specifications are measured according to EIA standard RS-490.]m Continuous Average Output Power (20–20,000 Hz)
Stereo operation
480 watts per channel into 1 ohm ( )(both channels driven)
240 watts per channel into 2 ohms
120 watts per channel into 4 ohms
60 watts per channel into 8 ohms
Monophonic operation(bridged connection)

960 watts into 2 ohms ( )480 watts into 4 ohms
240 watts into 8 ohms

Note: Load ratings marked ( ) apply only to operation with music signals.
m Total Harmonic Distortion

Stereo operation (both channels driven)
0.07% with 2 ohm load
0.05% with 4 to 16 ohm load
Monophonic operation (bridged connection)
0.03%, with 4 to 16 ohm loadn Rear Panelm Intermodulation Distortion

0.01%m Frequency Response

At rated output:
At 1 watt output:

m Gain28.0 dB (with GAIN selector at MAX)
(Stereo and monophonic operation)

m Gain Selection

MAX, –3 dB, –6 dB, –12 dB

m Output Load impedance

Stereo operation:
2 to 16 ohms
Monophonic operation: 4 to 16 ohms

20 - 20,000 Hz +0, –0.2 dB
0.5 - 160,000 Hz +0, –3.0 dB

With music signals only, 1-ohm loads are permissible forstereo operation and 2-ohm loads for monophonic operation.
m Damping Factor

400m Input Sensitivity (with 8-ohm load, GAIN selector in MAX position)
Stereo operation:
0.87 V for rated continuous average output (60 W)
0.11 V for 1 watt output
Monophonic operation:m Input Impedance

1.74 V for rated continuous average output (240 W)
0.11 V for 1 watt output
Balanced: 40 kilohms

Unbalanced: 20 kilohms

m Signal-to-Noise Ratio (A-weighted, input shorted)
115 dB (GAIN selector at MAX)
121 dB (GAIN selector at –12 dB)
At rated continuous average output

A Hold time indicator
B Right/left-channel output power meters(digital and bar graph, switchable)
C Input type indicators
D Bridge mode indicator
E Meter selector(Meter OFF, range, bar graph)
F Hold time selector button 1 SEC,G Power switch
H Input selector button
UNBALANCED, BALANCED
I Gain selector
MAX, –3 dB, –6 dB, –12 dB

J Right/left-channel speaker outputterminals
K Unbalanced inputs
L Balanced inputs
a Ground b Inverted (–)
c Non-inverted (+)
M Mode selector
DUAL MONO, NORMAL, BRIDGEN AC power supply connectorm Output Level Meters (digital indication and bar graph)
Digital meters:
5-digit indication, selectable range: 10W/100W/1000WBar graph meters:
25-point scale
Hold time:
1 second/ , switchable
Display off setting provided
Monophonic operation: same value for left/rightm Power Requirements
AC 120 V/230 V, 50/60 Hz(Voltage as indicated on rear panel)m Power Consumption

280 watts idle
530 watts accordance with IEC 60065

m Maximum Dimensions

Width 465 mm (18-5/16")
Height 238 mm (9-3/8")
Depth 515 mm (20-1/4")

m Mass43.0 kg (94.8 lbs) net
52.0 kg (114.6 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 cordmSpecifications and design subject to change without notice for improvements.

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