Accustic Arts MONO III MK2 User manual

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To our valued customer and music enthusiast,
with the purchase of your new ACCUSTIC ARTS®MONO III –MK 2 you have opted for a product which
incorporates the most modern technology to achieve excellent sound and quality. To make sure that you have
pleasure for as long as possible with your amplifier we kindly ask you to thoroughly read this instruction manual
through to the end.
We wish you many enjoyable hours of listening to music with your new unit.
ACCUSTIC ARTS®/ Lauffen (Germany)
C o n t e n t
1 MONO III –MK 2 highlights ____ Page 2
2 Important safety instructions ____ Page 3
3 Introduction and positioning ____ Page 4
4 Installation ____ Page 5
4. 1 Input selection: balanced / unbalanced
4. 2 Damping factor linearization
4. 2. 1 General information
4. 2. 2 The technical part
4. 2. 3 Claims and reality
4. 2. 4 Solution: damping factor linearization
4. 3 Mute function
4. 4 Loudspeaker cables and correct phase for the loudspeakers
4. 5 Connection to mains power
4. 6 Replacing damaged mains fuses
5 Start-up ____ Page 10
5. 1 Description of function
5. 2 Operating instructions
6 Looking after your amplifier ____ Page 11
7 Troubleshooting ____ Page 11
8 Specifications ____ Page 12
9 Copyright, trademarks, warranty ____ Page 13
1 MONO III –MK 2 highlights
▪Extremely powerful mono power amplifier
▪20 selected MOS-FET output transistors in premium quality
▪Magnetically shielded and encapsulated toroidal core transformer
▪Optimum smoothing thanks to more than 110,000 µF power supply capacity; Premium quality capacitors
▪Very high damping factor for perfect speaker control
▪ACCUSTIC ARTS® damping factor linearization (switchable)
▪Professional protective circuit against clipping, HF oscillations and too high DC offset
▪Switch-on current limitation for highest operational safety
▪Constant low operating temperature due to generously dimensioned heat sinks
▪Balanced input (XLR) and unbalanced input (RCA) –inputs are switchable
▪Very high quality WBT speaker terminals (bi-wiring / bi-amping)

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▪Extremely stable housing, fully made of aluminium; inlay made of massive brass, polished and chromed
▪ACCUSTIC ARTS®MONO III –MK 2 is “Handmade in Germany”
2 Important safety instructions
▪Read these instructions.
▪Keep these instructions.
▪Follow all instructions.
▪Do not use this appliance near water.
▪Never use this appliance near hot surfaces.
▪Never use this appliance outside and always place it in a dry environment.
▪Check that your mains voltage corresponds to that stated on the appliance.
▪Never leave the appliance unsupervised when in use. Always keep electrical equipment out of the reach of
children.
▪Never pour or spill liquids directly onto this appliance.
▪Never operate this apparatus in an explosive atmosphere.
▪Do not put any vases or similar objects containing water or liquids on top of this appliance.
▪Unplug this appliance during lightning storms or when unused for long periods of time.
▪Ensure that the appliance has sufficient air around it and avoid extreme temperature influences on the unit,
especially direct sunshine and high humidity.
▪The mains cable of this appliance is equipped with an equipment grounding conductor. This equipment
grounding conductor must never be disconnected or taped over. In case any humming occurs, please contact
your authorized dealer.
▪Always disconnect the appliance from the mains power before carrying out any changes to the cables or when
cleaning the appliance.
▪Protect the mains cable from being walked on or pinched particularly at plugs and the point where they exit
from the appliance.
▪From time to time check the mains cable and the appliance for damages. Take care that the mains cable is not
buckled or damaged by any house pets.
▪Never move the appliance by pulling the mains cable. Make sure the mains cable cannot get caught in any way.
Do not wind the mains cable around the appliance and do not bend it.
▪Never use accessories which are not recommended by the manufacturer. They could constitute a danger to the
user and risk to damage the appliance.
▪Never operate the appliance with the housing open.
▪To clean the aluminium housing, please only use a cloth moistened with water and some detergent. Never use
inflammable or chemically aggressive cleaning agents.
▪In the event of a defect, please never attempt to repair it yourself. Any tampering with the appliance by an
unauthorised person will make the warranty void. Please get in contact with your authorized dealer.
▪Refer all servicing to qualified service person. Servicing is required when the appliance has been damaged in
any way, such as power-supply cord or plug is damaged, liquid has been spilled or objects have fallen into the
appliance, the appliance has been exposed to rain or moisture, does not operate normally or has been
dropped.
▪Replace fuses only with original types having the same ampere value, the same voltage endurance and the
same time-lag. You can find the corresponding value in chapter 4. 5of this instruction manual.
▪Never bypass a fuse.
▪No user-serviceable parts inside.

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▪WARNING –DANGER TO LIFE! High voltage in the inside of the
unit. Never operate the unit with removed top cover and do never
touch the board while the unit is switched on!
The lightning flash with arrowhead symbol, within an equilateral triangle, is intended to alert the user
to presence of uninsulated “dangerous voltage” within the product’s enclosure that may be of
sufficient magnitude to constitute a risk of electric shock to persons.
The exclamation point within an equilateral triangle is intended to alert the user to the presence of
important operation and maintenance (servicing) instructions in the literature accompanying the
appliance.
Marking by the “CE” symbol indicates compliance of this device with the EMC (Electromagnetic
Compatibility) and LVD (Low Voltage Directive) standards of the European Community.
Remarks in the manual:
WARNING!
Calls attention to a procedure, practice, condition or the like that, if not correctly
performed or adhered to, could result in personal injury or death.
CAUTION!
Calls attention to a procedure, practice, condition or the like that, if not correctly
performed or adhered to, could result in a damage or destruction to part or the entire
component.
To guarantee a reliable function of this unit over the long-term we kindly ask you to thoroughly read this
instruction manual before connecting this unit and to observe the following instructions. This is also necessary for
your own safety when dealing with the unit.
VERY
IMPORTANT!
Never leave the appliance unsupervised when in use. Always keep electrical
equipment out of the reach of children.
VERY
IMPORTANT!
After switching the unit off please wait 60 seconds before switching it on again.
VERY
IMPORTANT!
Never use the unit in a room with temperature more than 25 °C and high humidity.
Never use the unit outside.
3 Introduction and positioning
The MONO III - MK 2 is a powerful power amplifier. Please read through all important information provided by this
instruction manual for the handling and operation of this top-quality high-end product.
The weight of this MONO III –MK 2 is approx. 60 kg / 132 lbs. Great care must be exercised when unpacking the
unit. Due its high weight a minimum of two people should unpack the amplifier out of its box.

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Carefully store the transportation packaging for the possibility of further use. If you have a claim on the warranty,
always use the original packaging for any necessary transportation. Transportation without this packaging can lead
to damage to the housing.
Please check, if the following items are included:
1 x AC mains cable (type depends on your country)
2 x replacement fuses for FUSE 1 / FUSE 2 (type depends on your mains voltage)
Provided there is available space the power amplifier should, if possible be positioned as close as possible to the
loudspeakers since the loss within the loudspeaker cable is generally higher than with interconnect cables.
Therefore always use the shortest possible loudspeaker cable but of equal length on the left and right side.
Due to these facts and due to its high weight the power amplifier is usually set up in a position near to the floor
either between or near the loudspeakers. If you cannot set up the power amplifier in a free position, then under
no circumstances should the chimney effect of the heat sinks be restricted. Therefore leave a minimum of 5 cm
distance at the sides and 10 cm distance above the housing cover. Take care that the base of the power amplifier is
always stable and level.
Please do not put any other electronic products (e.g. preamplifier, CD player, turntable etc.) directly on the AMP II
–MK 3, instead please use a suitable hifi-rack.
VERY
IMPORTANT!
CAUTION ! DANGER OF FIRE !
Please never cover the ventilation slots or the heatsinks.
This could lead to overheating of the power amplifier and cause serious damage or fire.
Please never put any other electronic products or other objects directly on the AMP III
–MK 2.
Fig. 1 Distance to walls and objects

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4Installation
Fig. 1: Rear panel
1Mains socket
2FUSE 1: Fuse socket for protection of transformer 1 / right channel
3FUSE 2: Fuse socket for protection of transformer 2 / left channel
4INPUT SELECTION: see Fig. 2 in chapter 4. 1
5.1 AUDIO INPUT BALANCED: Balanced XLR input socket for the preamplifier output signal
5.2 AUDIO INPUT UNBAL.: Unbalanced RCA input socket for the preamplifier output signal
6.1 SPEAKERS RIGHT: Right loudspeaker output socket pair A
6.2 SPEAKERS RIGHT Right loudspeaker output socket pair B
6.3 Ground contact for shielded speaker cables
7.1 SPEAKERS LEFT: Left loudspeaker output socket pair A
7.2 SPEAKERS LEFT: Left loudspeaker output socket pair B
7.3 Ground contact for shielded speaker cables
8DAMPING CONTROL: see Fig. 4 in chapter 4. 2
9MUTE: The switch MUTE is designed for very short listening interruptions, e.g. connection speaker
cables; please see chapter 4. 3

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4. 1 Input selection: balanced / unbalanced
The MONO II I–MK 2 has balanced XLR input sockets 5.1 and unbalanced RCA input sockets 5.2. To connect a
preamplifier, please use one of them.
Fig. 2: INPUT SELECTION
Please press the button INPUT SELECTION to use the balanced XLR input
AUDIO INPUT BALANCED or release the button to use the unbalanced
RCA input AUDIO INPUT UNBAL.
You can use either the balanced input or the unbalanced input but not
at the same time.
In order to connect this amplifier with a separate preamplifier, e.g. the TUBE PREAMP II from ACCUSTIC ARTS®,
please use interconnect cables with best possible shielding and high quality connectors. This is the only way to
ensure that the sound quality of the power amplifier is fully exploited.
Fig. 3: Pin declaration of the balanced input (XLR)
Pin 1: Ground (shield)
Pin 2: Non-inverting (hot; 0°)
Pin 3: Inverting (cold; 180°)
These pin assignments comply with the standard adopted by the Audio Engineering Society. Refer to the operating
manual of your other units to verify that the pin assignments of their connectors correspond to your ACCUSTIC
ARTS® unit.
4. 2 Damping factor linearization
Fig. 4: DAMPING CONTROL ON/OFF
The damping factor linearization can improve the performance of your speaker. By pushing
this button the function is activated (= ON).
4. 2. 1 General information
The damping factor Dof a power amplifier is determined from the load resistance RL(connected loudspeaker, but
for the measurement assessment 8 Ω resistance) divided by the internal resistance of the amplifier Ri.
Physical equation: D = RL/ Ri
D : damping factor (calculated number)
RL : load resistance (connected loudspeaker, for the measurement assessment 8 Ω resistance) *
Ri: internal resistance of the amplifier (usually measured at 1 kHz) **

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Example: A power amplifier has (at 1 kHz) the internal resistance Ri=16 mΩ
The damping factor is then calculated to be 500. Physical equation: 8 Ω / 0.016 Ω = 500 ***
This is a typical value for modern transistor power amplifiers.
(In comparison: at 1 kHz full tube power amplifiers usually have an internal resistance in the range of 0.4 Ω to 4 Ω
and therefore a calculated damping factor in the range of 2 to 20)
Technical background:
* Loudspeakers do not have the same resistance at all frequencies. They are characterized by dynamic resistance, whereby the so-called
complex load is formed by the spring mass system, deflection and movement speed of the membrane, induced counter-voltage in the
voice coil, and crossover.
** The internal resistance of a power amplifier is also a dynamic variable. It is only valid for a certain working point, with a certain frequency
and for a certain modulation. In addition, it can be determined in a number of ways.
*** These above-mentioned mathematical considerations do not take the loudspeaker cable resistance values or contact resistance (banana
connector, cable lugs, etc.) into account. In reality these loudspeaker series resistance values and contact resistance values are naturally
added to the internal resistance.
4. 2. 2 The technical part
As described above, due to the required high negative feedback reserve modern high power amplifiers with
transistors have very low internal resistance (Ri) and therefore high damping factors. These high damping factors
are desired because they have a very positive effect on important technical parameters, e.g. on distortion
characteristics.
At 5 kHz the damping factor of a power amplifier is relatively linear and has a high value, but then for physical
reasons (limitation of bandwidth) goes down with higher frequencies.
The degree and progress of the damping factor influence the in- and outswing behaviour and therefore the control
of the connected loudspeaker by the power amplifier.
4. 2. 3 Claims and reality
Claims are often made that a higher damping factor is better for controlling the loudspeaker and therefore the
system sounds better. This is not the case.
Correct is that a power amplifier with a very low damping factor is not able to sufficiently control the loudspeaker.
It is, however, true that a loudspeaker does not have the best outswing behaviour with the maximum damping
factor.
The truth is that the value of the damping factor should in fact be within a certain range which is ideal for the
loudspeaker and should also be linear for as long as possible over the frequency range.
4. 2. 4 Solution: damping factor linearization
In order to meet these two requirements (ideal range and linear curve), in the switch position "DAMPING FACTOR
- ON"we lower the complete value of the damping factor slightly to the ideal value and then linearize it over a
wide frequency range. In this process the advantageously high negative feedback reserves remain completely
intact (see text above). If the push switch on the rear is not pressed, the function is not activated. The absolute
damping factor is then maximized, but from 5 kHz decreases considerably. According to his preference, the
customer can choose to activate the damping factor linearization or not.

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Fig. 5: This simplified diagram serves to illustrate damping factor linearization
4. 3 Mute function
Fig. 6: Positions of the MUTE switch
When the switch MUTE is pressed, the speaker outputs of the unit are turned off. The blue
LED is still illuminated, but the speakers get no signal.
Releasing the switch MUTE activates the speaker outputs.
The switch MUTE is designed for very short listening interruptions, to keep the unit on perfect temperature (=
optimized sound). If you’re not going listen music for a longer time (e.g. more than 1 hour), please always switch
off the unit completely by pressing the main power switch 13on the front.
IMPORTANT!
Please use the MUTE function when connecting speaker cables. It prevents short
circuits.
4. 4 Loudspeaker cables and correct phase for the loudspeakers
For each channel the power amplifier has 2 pairs of WBT loudspeaker terminals labelled A and B. With this
arrangement you can wire your loudspeaker system in a BI-WIRING mode. If you want to control your
loudspeakers with only one cable you can either use pair Aor pair B. Both connections are identical and therefore
have exactly the same characteristics.
Please use only high-quality loudspeaker cables. This is the only way to ensure that the sound quality of the power
amplifier is fully exploited.
To connect the cables to the power amplifier or loudspeakers if possible, use high quality terminal ends or banana
plugs*) and avoid connecting bare litz wires (except: OFC-cables) since these corrode and so restrict the signal flow.
The terminals on your power amplifier and your loudspeaker are colour coded or marked with a plus (+) and minus
(-). Connect the red (+) output terminal of your amplifier with the red (+) input terminal of your loudspeaker. Proceed
in the same way with the white or black (-) terminals.

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IMPORTANT!
Avoid short circuits!
Never connect the output terminals of your power amplifier to each other. Neither connect
red (+) with white or black (-) of the channel nor the channels to each other.
4. 5 Connection to mains power
Only connect the power amplifier to the mains power when all the other cable connections have already been
carried out. Plug in the mains cable firstly in the inlet connector socket 1 of the power amplifier and only then the
earthing pin-plugs in the mains socket.
By actuating the mains power switch 13, you can switch the unit on or off. For further details, please read chapter
5. 2.
4. 6 Replacing damaged mains fuses
Replace fuses only with original types having the same ampere value, the same voltage endurance and the same
time-lag. Never use fuses with other ampere classes or time-lag classes.
IMPORTANT!
Pull out the mains plug!
Always disconnect the unit from the mains power before replacing a fuse.
To change the fuses FUSE 1 and FUSE 2 please use a screwdriver suitable for the slot in the fuse holder. Press the
screwdriver lightly into the slot and only then turn anticlockwise. Now you can take out the fuse holder and replace
the fuse.
For countries with 220 - 240 V / 50-60 Hz
please use the following fuse types:
For countries with 100 - 120 V / 50-60 Hz
please use the following fuse types:
Fuse F1 / F2: 10 Ampere, time lag
Fuse F1 / F2: 16 Ampere, time lag

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5 Start-up
Fig. 7: Front view
10 LED (red) indicates protection mode during warm-up or error on the left output stage channel
11 LED (red) indicates protection mode during warm-up or error on the right output stage channel
12 LED (blue) indicates ready for operation
13 Mains power switch to switch on the AMP III –MK 2
5. 1 Description of function
The two red LEDs (10 and 11) signal that the output relay of the output stage channel is open and that means that
the transmission of a music signal to the connected loudspeaker is interrupted.
The blue LED 12 in the middle signals that the unit is switched on (operational status).
To connect the unit to the mains socket, please press the mains power switch 13 on the front of the unit. To start
your listing music please check, if the MUTE switch 9 on the rear isn’t activated.
After switching on the mains switch 13 all three LEDs will turn on. After approx. 5 seconds the two red ones will
extinguish, while the blue LED stays on showing that the unit is running.
5. 2 Operating instructions
▪Switching on: Always switch-on the power amplifier last, i.e. after the other devices in your system
(preamplifier, CD player, etc).
▪Switching off: Always switch-off the power amplifier first and then switch-off the other devices from the
mains power.
▪When you switch off the unit from the front panel the auxiliary transformer remains connected to the mains
power. The power consumption is minimal. However, for longer periods of absence always disconnect the
power amplifier from the mains power by pulling the mains plug from the socket.
▪During a thunderstorm please completely disconnect the unit from the mains power by pulling out all three
plugs.
▪Avoid unnecessarily frequent switching the power amplifier on and off. The high amount of switch-on current is
a heavy burden for the electrical components and so the life of the unit will be shortened by this action.

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VERY
IMPORTANT!
WARNING!
After switching the unit off please wait 60 seconds before switching it on again.
6 Looking after your amplifier
This unit from ACCUSTIC ARTS® does not require special treatment in excess of the usual care taken with high
quality devices. Clean the housing with a dry or slightly moistened cloth. Please do not use any aggressive
detergents or detergents which contain silicon.
The best way to clean the chromed front plate is with a mild non-aggressive fat-dissolving detergent (e.g. glass
cleaner). Use a very soft clean cloth and wipe the front plate with this without exerting strong pressure. Never use
abrasive agents or polishing agents with abrasive particles.
VERY
IMPORTANT!
CAUTION ! DANGER OF FIRE !
Never place the unit in direct sunshine and avoid extreme changes in temperature.
7 Troubleshooting
Malfunctions are mostly caused by something simple which can be put right quickly.
In the next section some possible malfunctions are described together with their corrective action. However, if it is
not possible to remove the malfunction please contact your authorized dealer.
Malfunction The unit is switched on, the blue LED is illuminated but you hear no music.
Cause 1 The interconnect or speaker cables are not properly connected.
Solution Switch off all units and check all connections
Cause 2 MUTE switch is activated.
Solution Turn on the MUTE switch (see chapter 4. 3).
Malfunction The left or right LEDs do not go out approx. 5 seconds after switching on the unit or light up
during operation.
Cause 1 Clipping due to overload of the power amplifier.
Solution Lower the volume on your control device (e.g. preamplifier).
Cause 2 Overheating of the unit.
Solution Switch off the unit for approx. 30 minutes and then make sure that the unit has adequate
cooling.
Cause 3 Short circuit at speaker outlet.
Solution Check the loudspeaker terminals and correct it if necessary
Malfunction Crackling or humming in the loudspeaker.
Cause Contact problems on the input sockets or on the loudspeaker terminals.
Solution Switch off the unit and check the contact on the input sockets and on the loudspeaker terminals.

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8 Specifications
Inputs: 1 x RCA (unbalanced)
1 x XLR (balanced)
Input impedance: RCA - 15 k
XLR - 16 k
Output: 2 loudspeaker terminals (WBT)
Minimum loudspeaker impedance: 2 
Voltage gain: 30.0 dB
Rated power output: approx. 1,500 watts on 2 
(at THD+N = 0,1 %) approx. 1,350 watts on 4 
approx. 880 watts on 8 
(at each THD + N = 0,1% at 230VAC)
Distortion factor (THD+N): 0,003% on 4 load at 1kHz and 10 watts
Frequency response 10 Hz –50,000 Hz (+0/-0,5dB)
(at 10 watts on 4 )
Signal to noise ratio: -96 dB A (ref. 6.325 V)
Power consumption at idle: appr. 120 watts
Loading and screening capacity: > 110,000 µF
Zero signal current setting: 300 mA
Protection circuits: clipping, HF oscillations and too high DC offset
Dimensions (H x W x D) 350 x 482 x 430 mm / 13.8 x 19 x 16.9 inches
Weight: approx. 60 kg / 132 lbs.
9Copyright, trademarks, warranty
Copyright:
This instruction manual was correct at the time of going to press. The manufacturer reserves the right to make
changes to the technical specification without prior notice as deemed necessary to uphold the ongoing process of
technical development.
This manual is done by ACCUSTIC ARTS Audio GmbH.
Copyright © 2016. All rights reserved.
Trademarks:
ACCUSTIC ARTS®is a registered trademark of ACCUSTIC ARTS Audio GmbH.

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Warranty:
The manufacturer accepts no responsibility for damage caused by not adhering to this instruction manual.
Modification or change to any part of the product by unauthorized persons releases the manufacturer from any
liability over and above the lawful rights of the customer.
If a warranty claim occurs, first contact your dealer. If a possible fault is confirmed there and cannot be remedied
by the dealer, send the device to the service center responsible for your country. For information, contact your
dealer or distributor in your country. In any case, please use the original packaging for return transport to the
dealer or service center. Pack your device carefully. We accept no liability for damage caused by transport.
Recycling:
If at some point the device is no longer used and needs to be disposed of, use the recycling stations or delivery
points provided in your country. Never throw the device into the household waste. This also applies to the
batteries used in the remote control. Dispose of used batteries only at certain recycling facilities or collection
points.
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