Class-A

STEREO POWER AMPLIFIER● Class A driven output stage with 10-parallel push-pull power MOS-FETs● Large linear output of 65 W / 8 ohms, 130 W / 4 ohms, 260 W / 2 ohms, 520 W /1 ohm ● Instrumentation amplifier principle ● Current feedback amplification
circuits ● Balanced remote sensing ● MCS+ circuitry ● High damping factorof 1,000 ● Speaker output protection ● Highly responsive large-scale bar
graph power meters ● Supports bi-amping and bridged mode connection

The ideal stereo power amplifier building on 50-year search for perfection
The A-80 is a Class A power amplifier developed as a stereo amplifier version of our 50th anniversary A-300 model. Optimizing
the 10-parallel push-pull power MOS-FETs in the output stage produces an output power of 65 W into 8 ohms, 130 W into 4ohms, 260 W into 2 ohms, and 520 W into 1 ohm. Rigorous investment into new, cutting-edge noise reduction technologies hasachieved a sense of presence and minute expression that rival live performances. The A-80 power amplifier perfectly fuses
modern technology with the wealth of knowledge Accuphase has amassed in its pursuit of perfect sonic expression.

Groundbreaking technology
The A-80 employs sophisticated circuitry and hand-selected materials to create a power amplifier with perfectly honed expressiveness.
■ Ample output power■ MCS+ circuit■ Balanced remote sensing
Balanced remote sensing improves damping
factor by feeding back the GND at the sametime as the signal output from speakerterminals.

The Class A driven 10-parallel push-pull power
MOS-FETs in the output stage produce linear
output power of 65 W into 8 ohms, 130 W into 4ohms, 260 W into 2 ohms, and 520 W into 1 ohm.

By placing the voltage amplification stage in atwo-parallel circuit layout, the MCS+ (MultipleCircuit Summing-up) circuit theoreticallyreduces the noise floor by about 30%.
2-parallel circuit■ High noise performance

Signalfeedback

Ideal gain distribution and other sophisticatedtechniques improve noise level suppression
by 7% over conventional models.
7% improvement
A-80

16.2μV

Conventionalmodels

17.4μV＋＋

Signal sensing point(closest speaker terminal)

Poweramplification

Input−

GND
feedback

Input＋

GND sensing point(closest speaker terminal)

Output−Speakerterminals

MCS+ circuitry−

Noise level■ Instrumentation amplifier■ High damping factor

With balanced circuits in the signal input section,
the amplification stage is comprised entirely of an
instrumentation amplifier principle that equalizes
input impedance on the + and – sides for excellent
external noise suppression, while providing optimal
circuitry for a high-end audio amplifier.

With a damping factor of 1,000, the speakers can bedriven with full control over the counter-electromotive forces to get the most out of your speakers.

■ Ideal gain distribution
Allocating a high gain (12.6×) in the signal input
section with its superb noise suppression
rating drastically reduces output noise.
Input
signal+Input

Transmission signal

12.6×

2×+＋–+

Input
Outputsignal–Output−‑+Signal
Power
input section amplification section

BIAS

BIAS＋−Input+ B2

I-V
converter

BufferCurrent
summing

OutputCurrent NFB
network

BufferPoweramplification section

Protection circuit section

Power amplification stage

Output drive stage

MCS＋

The current feedback amplification circuit
offers exceptional performance in the highrange with almost no impact on the frequency
characteristics even when gain is switched,resulting in natural and dynamic driving of
the speakers.

Speakerterminals

Power amplification section[GAIN 6 dB / 2×]
Voltage amplification stage■ Current feedback amplification topology−Signalinput section

Signal input section[GAIN 22 dB / 12.6×]+ B1＋–2-parallel circuit layout of MCS+ principle+ B2 + B310-parallel push-pull power
MOS-FET output stage+ B4- B1+ INPUT
GND

BIAS

Parallel symmetricaldifferential input circuits

GAIN
Selector
BIAS- INPUT- B2+ B2

NFB
Network

Toroidaltransformer

OUTPUT

BIAS

GND

+ B1
BIAS

BIAS

- B2 - B3- B4- B2- B1
NFB
Network
DC−Feedback
AMP＋Circuit diagram

L ch power
amplification section

Filtering
capacitors

R ch power
amplification section

Advanced features■ Class A driven 10-parallel push-pull MOS-FET output stage■ 65 W into 8 ohms, 130 W into 4 ohms, 260 W into 2 ohms,
and 520 W into 1 ohm large linear output power■ Instrumentation amplifier■ Current feedback amplification topology■ Balanced remote sensing■ MCS+ circuitry■ High damping factor of 1,000■ Meter display switching ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・①■ Digital power meter display switching ・・・・・・・・・・・・・・・・・・・・・・・・・・・・②■ Hold time switching function that changes the meterpeak display time ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・③■ LINE / BALANCED input switching ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・④■ 4-step gain control ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・⑤■ Polarity switching of balanced input connectors ・・・・・・・・・・・・・⑥■ Bi-amping connection and bridged connection switching・・・⑦■ Signal input section with a fully discrete configuration
for low noise ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・⑧■ Speaker output protection circuit guards against
short-circuiting ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・⑨■ Large speaker terminals connected directly to protection
circuitry ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・⑩■ Edgewise coils improve damping factor ・・・・・・・・・・・・・・・・・・・・・・・・・⑪■ Highly reliable MOS-FET switches with no mechanicalconnections ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・⑫■ Large, high-efficiency toroidal transformer ・・・・・・・・・・・・・・・・・・・・・⑬■ High capacity 120,000 μF filtering capacitors ・・・・・・・・・・・・・・・・・・⑭■ Aluminum hairline finish top plate ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・⑮■ Highly responsive large-scale bar graph meters anddigital power meters ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・⑯■ High-carbon cast iron insulator feet with superior damping
characteristics ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・⑰■ Power amplification section on circuit boards using
glass cloth fluorocarbon resin ・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・・⑱

Sub Panel

Rear Panel①Meter display ②Meter display ③Hold time ④Input

selector

range selector

selector

selector

selector⑧Signal input section⑥Balanced

input polarity
selector⑦Operation mode

selector⑨Protection circuit section⑩Speaker terminals⑪Edgewise coil

⑫MOS-FET switches⑬Toroidal transformer⑭Filtering capacitors⑮Top plate⑯Power meters⑱Power amplification section⑤Gain⑰Insulator feetBi-amping Connection

Bridged Connection(High quality performance that eliminates interaction between high and low ranges)(4× greater power output)

R Speaker

L Speaker

Jumperconnection

Jumperconnection

LRRL

Jumpers
removedL

RR

R L
L input

L

R L
Uses A-80 LLOperationmode selector

R

R Speaker

L SpeakerL input

RLRL

RL

RL

R L
Uses A-80 R

2 units (BRIDGE)

Operationmode selector

L input

R L
Uses A-80 L
L(lit)

Preamplifier

Operationmode selectorR

BRIDGE indicator(front panel)

Front Panel
BRIDGE
indicator

Sub panel

L input

Uses A-80 R

Operationmode selector

2 units (DUAL MONO)(lit)

Operation modeselector (rear panel)

DUAL MONO
indicator (front panel)Preamplifier
Operation modeselector (rear panel)

Meter hold time
indicator

Jumpers
removedDUAL MONO
indicator

Power switch

Rear PanelPowermeters

Speaker terminals(Upper and lower terminals
always output the same signal)

Input
indicators

Button for opening
the sub panel* See the previous page for information on the controls in the sub panel.

Supported spade lug dimensions
Min.
6.3 mm(0.25”)

Max.
19 mm(0.74”)

AC power
supply connector
Operation mode selector
Balanced input phase switch

LINE input terminals
BALANCED input terminals

Guaranteed Specifications
Load
8 ohms 4 ohms 2 ohms 1 ohm
Normal / Bi-amping connection 65 W
130 W＊1 260 W＊1 520 W＊1＊1
Bridged connection
260 W520 W＊1 1,040 W＊1ー2ohms
0.07 %
Normal/Bi-amping
Total Harmonic Distortion
connection
4 to 16 ohms
0.03 %(20 – 20,000 Hz, At ratedoutput)
Bridged connection
4 to 16 ohms
0.05 %
Intermodulation Distortion
0.01 %At rated output
20 – 20,000 Hz (+0, –0.2 dB)
Frequency Response
0.5 – 160,000 Hz (+0, –3.0 dB)
At 1 W output
Damping Factor
1,000 or greater
Input Impedance
BALANCED / LINE input
40 kilohms / 20 kilohms
At rated output
At 1 W output
OutputInput Sensitivity
Normal / Bi-amping connection
0.91 V
0.11 V
Bridged connection
1.82 V
0.11 V
Rated Output(20 – 20,000 Hz)

Signal-to-Noise Ratio(A-weighted, input shorted)

Gain switch at
MAX / –12 dB

123 dB / 129 dB＊1: Limited to music signals

Gain
Power Meters
PowerRequirements

Gain switch
MAX
íG%
íG%
íG%
Normal / Bi-amping connection 28 dB
25 dB
22 dB
16 dB
Logarithmic scale, with illumination off switch
FormatDisplay range
í∞ ~ +3 dB
Hold time
1 sec. / ∞ switchable
120/220/230 V AC, 50/60 Hz(Voltage as indicated on rear panel)PowerConsumption

Idle
In accordance with IEC 62368-1
Stand-byMaximum
Dimensions

Width 465 mm (18.3”) × Height 240 mm (9.4”) × Depth 515 mm (20.3”)

MassNetIn shipping Carton

211 W
260 W
0.3 W

44.6 kg (98.4 lbs)
54 kg (119 lbs)

The measurement methods for the Guaranteed Specifications comply with JEITA
CP-1301A and IEC 60268-3.
“Normal connection” indicates standard operation.

Supplied accessories● AC power cord
Remarks★ This product is available in versions for 120/220/230 V AC. Make sure that the voltage shown on the rear panel matches the AC line voltage in your area.
★ The 230 V version has an Eco Mode that switches power off after 120 minutes of inactivity.
★ The shape of the plug of the supplied AC power cord depends on the voltage rating and destination country.

●The specifications and appearance of this product are subject to change without notice.

https://www.accuphase.com

I2305Y

850-2236-00（B1） PRINTED IN JAPAN