● Pure Class A stereo power amplifier with outstanding S/N ratio and very high dampingfactor ● Rated for 60 watts into 8 ohms and 480 watts into 1 ohm ● Power MOS-FETs in10-parallel push-pull configuration ● Instrumentation amplifier principle ● All signal paths
realized with discrete semiconductor components ● Balanced Remote Sensing principle● MCS+ circuit topology ● Current feedback amplification principle ● Digital power
value readout and bar graph voltage indication ● Support for bi-amping and bridged modeA New Age Begins

With a Supreme Pure Class A Stereo Power Amplifier.

Instrumentation amplifier topology using discrete semiconductors realizes ideal gain allocation.
Balanced Remote Sensing optimizes efficiency of negative feedback. 10-parallel push-pull
configuration in power amplification stage. The overall result is outstanding S/N ratio andamazingly high damping factor. Furthermore, constant-voltage drive handles even drastic speaker
impedance fluctuations with ease. Power MOS-FETs and other carefully selected components andmaterials make this Pure Class A Stereo Power Amplifier a sheer delight to experience.

Technology development ahead of the curveHigh S/N ratio results in sparkling clarity
The A-75 uses a balanced instrumentation amplifier circuit configuration throughout all amplification stages, minimizing susceptibility tonoise and ensuring outstanding characteristics. The signal input
stage is configured with discrete semiconductors as a push-pull
circuit. This makes it possible to allocate a high gain of 22 dB (factorof approx. 12.6) to this section and conversely keep the gain of thepower amplification section to a low 6 dB (approx. x2.0). As a result,even large signal amplitudes are conveyed accurately from thesignal input stage to the power amplification stage, and noise
components processed in the amplification stage are kept low.
Compared to the previous model, this results in a noise reduction of11%. S/N ratio is rated at an astonishing 122 dB (at max gainsetting), which manifests itself in superb sonic clarity.

Signal input section
GAIN 22 dB

Amplification section
GAIN 6 dB++ INPUT–FEEDBACKNETWORK+OUTPUT

10-parallel
poweramplifier

GAIN CONTROLCIRCUITFEEDBACKNETWORK–Signal input section– INPUT

19.5 μV (S/N ratio: 121 dB)

Previous model–+17.4 μV (S/N ratio: 122 dB)

A-75■ Instrumentation amplifier principle

11% lower■ Output noiseHigh damping factor realizes ideal speaker drive
To correctly track the dynamic changes in loudspeaker impedanceand drive the speakers with ideal characteristics, the power amplifier
output impedance needs to be kept as low as possible, which in turnmeans an increase in the damping factor. To achieve this aim, theA-75 not only positions the negative feedback sensing point close to
the speaker terminals, it also obtains sensing information from theground line at the same time. This method is called Balanced
Remote Sensing. The aim is to minimize output impedance andtherefore achieve a significant increase of the damping factor.
Furthermore, ten power MOS-FETs with excellent current capacity
are used in a parallel configuration, and MOS-FET switches thateliminate all mechanical contacts guarantee outstanding long-termreliability. The edgewise coil with large cross-section area, Hallelement for current detection, and many other sophisticated features
further contribute to reduced output impedance. The end result is adamping factor rating of 1,000 which represents a 25% improvement
over the previous model.

+ INPUT+Signal Sensing–NFB
NETWORK+GAIN
CONTROL

POWERAMP.

MOS-FET switches– INPUT＋ Signal–NFB
NETWORK

Speaker Terminals–－ GND+

Ground Sensing■ Balanced Remote Sensing
25% improvement

800

Previous model

1000

A-75

■ Damping Factor

Edgewise coil

Output power characteristics suitable for constant voltage drive
A massive toroidal power transformer and large filtering capacitors(100,000 μF x 2) in the power supply ensure that plenty of power isavailable for handling high amplitude input signals, and large heatsinks efficiently dissipate any excess thermal energy. As a result, thepower amplification stage is rated for a continuous 60 watts into 8ohms, 120 watts into 4 ohms, 240 watts into 2 ohms and 480 watts
into 1 ohm (music signals). This linear power progression
demonstrates that constant voltage drive has been successfully
realized. The maximum output rating is 131 watts into 8 ohms, 232watts into 4 ohms, 370 watts into 2 ohms and 547 watts into 1 ohm(music signals). Although a Pure Class A Stereo Power Amplifier, theA-75 can easily drive even large and demanding speakers.
Signal input stage GAIN 22 dB

Power amplification stage with large
heat sinks

Massive toroidal transformer

Power amplification stage GAIN 6 dB
Voltage amplification stage
Power amplification stage
MCS+ (Multiple Circuit Summing)
Power MOS-FETs in 10-parallel push-pull configuration

GAIN < MAX, –3, –6, –12 dB >
+ B1

500
450+ B2Output power (W)

BIAS

- B1

Gain Selector

GND+ B4

BIAS+ INPUT

MAX-3 dB
-6 dB
-12 dBDC Servo

OUTPUT

BIAS－GND+ B1- INPUT

BIAS- B3- B4BIAS

BIAS- B1370W

350
300
250

232W

200
150 131W

240W

100

Feedback Network＋480W

400

BIAS

+ B3547W

550

- B2

■ Circuit diagram of amplifier section

Power MOS-FETs

120W

50

Max.
output power
Rated
output power

60W
8421Impedance (Ohms)■ Output power characteristics

Functionality ‒ Convenience that makes sense❶●❷●

❸●

❹●

●
❶ Meter selector for changing the meter display●❷ Digital power meter range selector for selecting the power indication range●❸ Hold time button for changing the value indication hold time❺●

● Input selector button for selecting the input signal❹● Gain selector for changing the amplification gain❺

Advanced Features■ Current feedback principle in signal input
stage and power amplification stage assures
excellent phase characteristics in high range.
■ MCS+ topology improves S/N ratio and THD
characteristics in voltage amplification stage.
■ Printed circuit board of power amplification
stage made from glass cloth fluorocarbon
resin.

Digital power meter/bar graph meter

Operation selector

Filtering capacitors■ Digital power meter showing output power
levels and bar graph meter showing output
voltage with indication range to –50 dB, bothwith on/off switching capability.
■ Speaker output short-circuit monitoring function ensures complete operation safety.
■ Two sets of large speaker terminals accept
spade lugs and also enable easy bi-wiring
connection.
■ Operation mode switch supports bi-amping
and bridged connection.
■ 4-stage gain selector.
■ Phase selector for balanced inputs.

Protection circuit assembly

Top plate with elegant hairline finish

Phase selector

6.3 mm or larger
Max. 19 mm

Supported spade lug dimensions

Connection example for bridged setup
Left speaker

Example for bi-amping connection

Right speakerIn bridged mode, a stereo power amplifier is used asa monophonic amplifier. Two A-75 units are needed
for the left and right channels. The output powerincreases by a factor of about 4, for even more
dynamic and powerful music reproduction.
＊ For signal input, only the LEFT terminals of both
A-75 units are used. The speaker terminals ofboth A-75 units are not used.
RIGHT

A-75 for left channel

ＬEFT

LOW

ＬEFT

RIGHT

LEFT
input

LEFT
input

Set the operation
mode selectorof each A-75
unit to BRIDGE.

"BRIDGE" LEDon front panel is lit.

Preamplifier

Left speaker

HIGH－A-75 for right channel＊ For signal input, only the LEFT terminals of both
A-75 units are used. The speakers must haveseparate inputs for the LOW and HIGH range.
＋－＋Power switch

Digital power meter
range selector
AUTO / 10W / 100W / 1000W

Hold time
selector button＋－LEFT
input

Set the operation
mode selector ofeach A-75 unit to
DUAL MONO.

LOWHIGH＋

A-75 for right channel"DUAL MONO"
LED on front
panel is lit.

Preamplifier

Rear Panel

Bridged connection indicator
Dual mono connection indicator
Input type indicators

Meter operation
selector
OFF / ALL / dB / W－LEFT
A-75 for left channel input

Front Panel
Digital power meter
Bar graph meter
Hold time indicator

Right speaker

In a bi-amped setup, the drivers for the LOW
frequency range and HIGH frequency range in aloudspeaker are driven by separate amplifiers. Two
A-75 units are needed for the left and right channels.
This can enhance sound quality even further.

Button for opening
sub panel
Gain selector
MAX / −3dB / −6dB / −12dB
Input selector button

Speaker terminals(Same signal at upper and lower connectors)

AC power supply
connector ★

Line input connectors
Balanced input connectors[Pin ② − Pin ③ + ]＊ Can be changed withphase selector switch

Operation selector
DUAL MONO / NORMAL / BRIDGE
Balanced input phase selector

GUARANTEED SPECIFICATIONS [Guaranteed specifications are measured according to EIA standard RS-490.]
Continuous Average Output Power (20 - 20,000 Hz) Note: Ratings marked with (＊) are for music signals only.
Stereo operation
480 W/ch 1-ohm load (＊)(both channels driven)
240 W/ch 2-ohm load
120 W/ch 4-ohm load
60 W/ch 8-ohm load
Monophonic operation(bridged connection)

960 W
480 W
240 W

2-ohm load (＊)
4-ohm load
8-ohm load

Total Harmonic Distortion Stereo operation (both channels driven)

0.07％
2-ohm load0.03％ 4 to 16 ohm load
Monophonic operation (bridged connection) 0.05％ 4 to 16 ohm load

Damping Factor

1000

Input Sensitivity(with 8-ohm load)

Stereo operation

0.87 V
0.11 V
Monophonic operation 1.74 V
0.11 V

Input Impedance

Balanced: 40 kilohms, Line (unbalanced): 20 kilohms

S/N ratio
122 dB GAIN selector in MAX position(A-weighted, with input shorted) 128 dB GAIN selector in −12 dB position
At rated continuous average output
Output Level Meters

Indicates output power (W) with 5 digits
Display range switchable
AUTO/10W/100W/1000W
Bar graph meter
Represents output voltage
value (dB) using 38 points
Hold time
1 second / infinite (selectable)＊ With indication off switch

Intermodulation Distortion 0.01％
Frequency Response

At rated continuous
average output:
20 to 20,000 Hz
At 1 watt output:
0.5 to 160,000 Hz

Gain

28.0 dB (GAIN selector in MAX position)(Stereo/monophonic operation)

Gain selector

Gain selector
Gain (dB)

Output Load Impedance

Stereo operation:
Monophonic operation:

MAX
28

–3 dB
25＋0＋0–0.2 dB–3.0 dB–6 dB
22–12 dB
16

2 to 16 ohms
4 to 16 ohms

＊ With music signals only, 1-ohm loads are permissible forstereo operation and 2-ohm loads for bridged operation.

for rated continuous average output
for 1 watt output
for rated continuous average output
for 1 watt output

Digital power meter

Power requirements

120 V, 220 V, 230 V AC (voltage as indicated on rear panel), 50/60 Hz

Power Consumption

260 watts idle
520 watts in accordance with IEC 60065

Maximum Dimensions

WidthHeightDepthMass

43.9 kg ( 96.8 lbs) net
54.0 kg (119.0 lbs) in shipping carton

465 mm (18.31")
238 mm ( 9.37")
515 mm (20.28")

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 AC inlet and plug of the supplied power cord depends on the voltage rating and destination country.

Supplied Accessory● AC power cord

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

5年間保証

G1805Y PRINTED IN JAPAN 850-2211-00（B1）