Audio Note DAC4.1x Balanced Technical manual

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DAC4.1x
Balanced
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DIGITAL TO ANALOGUE
CONVERTER
OWNERʼS INFORMATION
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1) IMPORTANT SAFETY INFORMATION
2) CE DECLARATION OF CONFORMITY
DISPOSAL
POWER REQUIREMENTS
3) INTRODUCTION
4) AUDIO NOTE DACs
5) INTRODUCTION
UNPACKING AND INSTALLATION
7) CONNECTION
10) OPERATION
11) TECHNICAL SPECIFICATIONS
12) WARRANTY INFORMATION
13) CONTACT INFORMATION
CONTENTS
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OTHER SAFETY PRECAUTIONS: -
Never touch the power cord with wet hands.
Always remove the power cord by grasping the plug, not the cable.
Never expose the unit to excessive heat or magnetism.
Never let an inexperienced person repair or reassemble the unit.
Never put anything, especially metal objects, inside the unit.
Never place excessive weight on the unit.
!
Do not store or operate this unit in areas of high humidity or in close
proximity to water / moisture.
Do not expose or immerse the unit in liquid of any kind.
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This product generates high levels of heat. Adequate ventilation must
be provided. Do not restrict airflow through any ventilation slots or
place the unit on any surface that may restrict airflow.
Valve equipment operates at extremely high temperatures;
KEEP OUT OF THE REACH OF CHILDREN AND ANIMALS.!
RISK OF SHOCK OR ELECTROCUTION! INTERNAL OPERATING
VOLTAGES ARE LETHAL!
Do not remove top cover, unless specifically instructed to do so in the user
manual.
This unit contains fuses and other safety components in accordance with
BS60065 requirements.
In the event of failure, replacement fuse or safety component must be of
the same part type and value.
!
This product must be earthed –ensure that the mains supply cable earth /
ground is correctly connected.
!
SUCH REPLACEMENT MUST ONLY BE CARRIED OUT BY A
QUALIFIED SERVICE TECHNICIAN.
Do not attempt to replace any fuses without first disconnecting the unit
from the mains electricity supply.
! IMPORTANT SAFETY INFORMATION !

POWER REQUIREMENTS
Power requirements for electrical equipment vary depending on your geographical
location. Please ensure that your unit meets the power requirements in your area.
The power requirement for your unit is marked on the serial number plate, located on
the rear panel.
If you are in doubt, please contact your dealer before plugging the unit into the mains
supply.
CE DECLARATION OF CONFORMITY
DISPOSAL
This product must not be disposed of as normal household waste. To
prevent possible harm to the environment please separate the product
from other waste to ensure that it can be recycled in an environmentally
safe manner. Please contact your retailer or the appropriate local
government office for collection facilities.
!
We declare under our sole responsibility that this product is in conformity
with the following standards or standardized documents:
BS EN 60065 in accordance with the regulations 73/23/EEC, 89/336/EEC
(from 1 January 1997)
CE 94
Peter Qvortrup,
Director
Audio Note (UK) Limited
25 Montefiore Road
Hove
East Sussex
BN3 1RD
United Kingdom
Tel: [phone]
Fax: [phone]
!

Thank you for purchasing this Audio Note (UK) product. With the correct care it
should give you many years of pleasure and enjoyment.
Please take the time to read all of the information in this manual before connecting
your new component to an electrical supply or your system, to ensure both your
safety and satisfaction.
Please note that due to our desire to continually improve products, specifications are
subject to change without notice. Therefore it is important to refer to the manual that
is supplied with your product for the most accurate information; manuals downloaded
from our website or obtained from other sources may no longer fully apply to your
product.
If you have any questions regarding the information contained within this document
or your new component, please feel free to contact us: -
Audio Note (UK) Limited
25 Montefiore Road
Hove
East Sussex
BN3 1RD
United Kingdom
Tel: [phone]
Fax: [phone]
e-mail: [email protected]o.uk
INTRODUCTION

Ever since its introduction, we at Audio Note have been highly critical of digital music
reproduction. This dissatisfaction was the instigating force in our quest to make
digital playback more dynamically realistic and less fatiguing.Although we cannot
defeat the inherent limitations of the format and its recording engineers, we have
elevated CD reproduction to a previously unattained level of quality and performance,
and with the DAC 5, we proudly present our most radically advanced and iconoclastic
digital circuit design so far.
To understand the path that led us to the development of our current range of Digital
to Analogue Converters, it is worth looking back at our ʻdigital historyʼ. Our first
defining assault was made in 1992 when we introduced the DAC3, which, with its
patented transformer / filter interface circuit, revolutionized CD play back.!What we
learnt from the experiments with the digital / analogue interface transformers and
filters in the DAC3 was that there had to be more information available on the discs
than previous believed.!Digital filters and the associated over sampling had been
broadly discussed, analyzed and criticized, but what no-one had done at this time
was to remove them altogether,to see what their real effects on ultimate sound
quality were. So, that is exactly what we decided to do, and the results were
dramatic, to say the least.
The improvements this completely new circuit topology introduced resulted in a level
of CD playback quality that was previously unimagined. To this day, we combine
these purely analogue filters (dubbed 1x oversampling™ direct from disc™
technology) with the finest components and materials available, including transformer
interfaces and the highest quality vacuum tube circuitry to produce a range of Digital
to Analogue Converters that are both refreshingly lifelike and free from conventional
digital restraints and mechanical artifacts.
Audio Note (UK) Digital to Analogue Converters

DAC4.1x Balanced
Congratulations on your purchase of the Audio Note (UK) DAC4.1x Balanced Digital
to Analogue converter.
It has been specifically engineered for sonic performance rather than technical
specification, and fulfills all Audio Note (UK) Level Four criteria: -
Pure Class A operation
Zero negative feedback
Single Ended circuit topology
Valve rectification
Materials and component quality
Extensive research into the fundamental properties of the data stream itself have
shown beyond doubt that,regardless of the theoretical advantages of the signal
manipulation employed in our competitors products, such as higher over sampling,
noise shaping, re-clocking or jitter reduction, these corrective measures greatly
interfere with the critical time domain requirements of the signal.
Music is a time continuum from start to end which when broken is irreparably
damaged,and no amount of clever manipulation can restore it to its original
time / frequency / amplitude duration or relationship, regardless of what the theorists
may tell you.
As a result,we have developed a way of excluding or bypassing all these corrective
measures, to allow the conversion from digital to analogue to be done without any
manipulation whatsoever. All we do is to reformat the data stream to allow the
converter chip to be able to interpolate the incoming information correctly.
In other words, the Audio Note (UK) DAC4.1x Balanced has no over sampling, no
jitter reduction, no noise shaping and no re-clocking. Having removed all of the digital
filtering that is required for over sampling, all filtering is done in the analogue domain
where it is easier to retain good,wide band phase-frequency and dynamically
coherent behavior. It uses the highest grade Analogue Devices AD1865, 18Bit stereo
converter chip solely because we found it to be the best sounding available (yes,
even better than the 20Bit versions!).
The filter-interface coils / transformers are of the highest possible quality, using 80%
nickel Super mu-metal cores. The air gaps in the two filter coils per channel are
matched across the full frequency range to within 0.1dB of each other,using a
specially designed program to supplement an Audio Precision System 2 test rig.

The DAC4.1x Balanced features an upgraded version of the M6 Line preamplifier
output stage, using the 5814a and 6463 double triode valves. This is coupled to an
output transformer, wound with Audio Note (UK) copper wire on a High B C-core.
With a 33:1 step-down ratio, this output transformer not only has exceptionally wide
frequency response, but also just about the absolutely best dynamic transfer function
possible. The analogue output has provisions for both unbalanced and balanced
operation, using the best available quality RCA and XLR connectors.
To power this spectacularly revealing arrangement, we have incorporated a dual
channel power supply with double choke filtering and vacuum tube rectification. This
technique not only provides excellent isolation between the digital circuitry and power
supply, but also provides well-isolated short and clean analogue signal paths. The
digital power supply is an exceptionally low noise, shunt-type.
Internal component quality of this caliber has never before been seen, in either
consumer or professional equipment. There is an abundance of Audio Note (UK)
capacitors and Audio Note (UK) Tantalum film resistors throughout the circuit.
Analogue stage filter inductors and internal wiring are all produced with our own
Audio Note (UK) wire.
Please take care when unpacking your DAC4.1x Balanced. Choose a clean, clear
location to unpack your unit. Be aware that the Pre Amplifier is very heavy; before
attempting to unpack or lift the unit, check the weight and if necessary use more than
one person so that it can be moved safely and easily.
We recommend that you retain and carefully store all of the original packing
materials, in case transportation / shipping is required at a later date.
Select a suitable location for the unit. This should be a dry, dust free and level area,
preferably shielded from direct sunlight and free from vibration. Also ensure that the
location is stable and capable of carrying the weight of the unit.
A suitable mains power outlet must be close to the location; power cords must not be
pulled or stretched tightly in an attempt to reach a wall socket. If the power cord will
not easily reach the socket, choose a closer location!
Please ensure that adequate ventilation for the unit is provided, and that airflow
through any ventilation slots in the unit is not restricted. We recommend a distance of
at least 20cm free space is maintained above the unit. Please also remember that
valve equipment operates at extremely high temperatures, so a position that is
inaccessible to children or animals is essential.
UNPACKING AND INSTALLATION
DAC4.1x Balanced continued…

Special Note –Make sure that all connectionsare tight and clean. For
best results use good quality audio interconnects. Although it is
perfectly acceptable to use cables manufactured by other companies,
for best results and performance, we recommend our own Audio Note
(UK) range of interconnects and loudspeaker cables. For further
information, please consult your nearest Audio Note (UK) dealer, or
alternatively please feel free to contact us directly.
Inputs The DAC4.1x Balanced is equipped with two digital inputs, consisting
of one single ended RCA socket, and one balanced XLR socket. Only
connect one input, as it is not possible to use both inputs
simultaneously.
Mains The DAC4.1x Balanced utilizes an IEC 320 mains inlet socket. Use the
supplied mains cable to connect the unit to the local mains supply.
The mains fuse is located in a separate fuse holder, situated below
the mains inlet socket.
Ground Post A ground post is provided for connection to the ground terminal
located on the following pre amplifier, or the preceding CD Transport.
If, after all connections have been made, you experience any ʻhumʼ
problems, experiment with linking the ground posts / terminals with a
short length of wire.
Outputs The DAC4.1x Balanced provides two unbalanced outputs, consisting
of two pairs of colour coded RCA / Single Ended sockets. RED is for
RIGHT channel connection, WHITE is for LEFT channel connection.
There is also a balanced output, consisting of a pair of ʻmaleʼXLR
sockets (see ʻBalancedʼsection, below).
RCA The two pairs of RCA / Single Ended outputs are identical, and are for
connection to a pre amplifier or recording device.
CONNECTION
RCA SOCKET,
CENTRE = POSITIVE / SEND.
RCA SOCKET,
SHELL = NEGATIVE / RETURN.

CONNECTION continued…
XLR MALE
OUTPUT
1
2
3
RCA
OUTPUT
SOCKET
BALANCED /
SINGLE ENDED
SWITCH
Balanced The DAC4.1x Balanced is equipped with custom designed and
manufactured output transformers, which utilize an improved output
and grounding scheme to provide the best possible connection to the
pre amplifier.
Below is a description of the various cable and connection options: -
The pin configuration for all Audio Note (UK)
XLR / BALANCED connections is as follows: -
PIN 1 Ground / Shield
PIN 2 Positive / Send
PIN 3 Negative / Return
The balanced and single ended outputs cannot be used
simultaneously; select the appropriate output using the toggle switch.
When using a pre amplifier with a true balanced input, the
ʻBALANCED / SINGLE ENDEDʼswitch may be set in either position.
When set to the ʻBALANCEDʼposition, the centre tap of the output
transformer secondary is connected to the DAC4.1x Balancedʼs
ground. When set in the ʻSINGLE ENDEDʼ(unbalanced) position, the
secondary ʻfloatsʼin relation to the DAC4.1x Balancedʼs ground. This
provides the option of either a low or high common mode impedance
to ground at the DAC4.1x Balancedʼs output. Experiment with both
positions to achieve the lowest background hum from the system.

CONNECTION continued…
CABLE CONFIGURATION OPTIONS
When connecting the XLR / BALANCED outputs to a pre amplifier with an
RCA / Single Ended input, the switch must be set to the
ʻSINGLE ENDEDʼposition.
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CONVENTIONAL: SCREEN CONNECTED AT BOTH ENDS
XLR FEMALE
XLR MALE
3
1
1
2
2
3
SCREEN
DAC5 OUTPUT
PRE AMP INPUT
SCREEN CONNECTED AT PREAMP END ONLY, TO
ELIMINATE GROUND LOOPS
3
2
1
2
1
3
SCREEN
XLR FEMALE
XLR MALE
DAC5 OUTPUT
PRE AMP INPUT
CABLE CONFIGURATION FOR XLR BALANCED
OUTPUT TO RCA UNBALANCED INPUT
2
1
3
SCREEN
XLR FEMALE
RCA MALE
DAC5 OUTPUT
PRE AMP INPUT

OPERATION
Once all the connections are completed and checked, ensure that the volume control
on your preamplifier / integrated amplifier is at the minimum setting.
Ensure that the CD Transport connected to the DAC4.1x Balanced is switched
ON. Source components should always be the FIRST components to be switched on
and the LAST components to be switched off.
Ensure that all pre and power amplifiers connected to the DAC4.1x Balanced
are switched OFF.
The above procedure minimizes the possibility of loud noises produced by
components at switch on being passed to the loudspeakers and possibly causing
damage.
Turn on the DAC4.1x Balanced by using the rocker switch located on the rear panel,
above the mains inlet IEC socket. The red ʻpower onʼindicator LED located on the
front panel should now be illuminated.
Turn on your pre amplifier / power amplifier / integrated amplifier. If you are using a
pre / power combination, always turn on the pre amplifier BEFORE the power
amplifier(s).
The DAC4.1x Balanced is now ready for operation!
Bedding in The DAC4.1x Balanced requires around 200 hours of initial use
(called “bedding in”) before the circuitry becomes stable and
optimum performance is realized. As the device “beds in” the
sound will become increasingly more smooth, detailed and
open. A warm up time of approximately 30 minutes is required
each time the device is switched on before optimum sonic
performance is reached.
Cleaning No special maintenance is required for the DAC4.1x Balanced.
Use a soft, clean lint free cloth to remove any surface marks
from the casework. For finger marks / grease, use a soft, clean
lint free cloth, lightly moistened with a solution of warm water
and mild detergent. Do not use any alcohol or solvent based
cleaning products, as they may damage the finish.
ENSURE THAT THE DEVICE IS SWITCHED OFF AND
DISCONNECTED FROM THE MAINS ELECTRICITY
SUPPLY BEFORE UNDERTAKING ANY CLEANING.
Valve Life The valves supplied with your DAC4.1x Balanced should
provide approximately 5 years of operation. They are specially
selected by us, and should only be replaced with valves of the
same type and specification. Please consult your Audio Note
(UK) dealer should your valves need replacing. Alternatively,
feel free to contact us directly.

INPUT
RCA 75Ohms SPDif
XLR 110 Ohms AES/EBU
OUTPUT IMPEDANCE
600 Ohms, Balanced or Single Ended
REFERNCE OUTPUT
3.2V RMS
CHANNEL BALANCE
Less than 0.2dB
TUBE COMPLIMENT
1 x 5814a
1 x 6463
1 x ECL82
1x 6X5
FUSE RATING
1.25A anti-surge (110 / 120V supply)
500mA anti-surge (220 / 240V supply)
UNIT WEIGHT
22 KG
SHIPPING WEIGHT
(ORIGINAL PACKAGING)
25 KG
UNIT DIMENSIONS
145mm (h) x 450mm (w) x 425mm (d)
SHIPPING DIMENSIONS
(ORIGINAL PACKAGING)
245mm (h) x 550mm (w) x 525mm (d)
DIGITAL SYSTEM
18Bit Ananloue Devices AD1865N
44.1 / 48 / 96KHz input capability.
NOTE
Due to Audio Note (UK)ʼs ongoing
research and development program,
specifications are subject to change
without notice.
TECHNICAL SPECIFICATIONS

Audio Note (UK) warrants this product to be free from defects in materials and
workmanship for two yearsfrom the original date of purchase from an appointed
Audio Note (UK) dealer, and agrees to cover the cost of parts and associated labour
required to correct such defects, subject to terms & conditions.
This Warranty is offered to the first purchaser only.
Any valves supplied with the unit are warranted for three months from the original
date of purchase.
If the product fails in normal domestic use and during the Warranty period due to the
above described faults or defects, Audio Note (UK) will,at its discretion, repair or
replace the item free of charge within a reasonable time once it has been returned to
Audio Note (UK) or an appointed Audio Note (UK) dealer or service engineer.
Audio Note (UK) is not liable for any shipping charges incurred whilst transporting the
product to or from Audio Note (UK) or an appointed Audio Note (UK) dealer or
service engineer, should the item require service or repair during or after the
Warranty period.
If the product must be shipped, please use the original packaging materials and
include a copy of the original sales receipt along with a note explaining, in as much
detail as possible, the problems you are experiencing with the unit.
Only use a reputable Courier Service or Shipping Agent, and ensure that your
product is insured during transit.
Any servicing, repairs or modificationsnot authorized by Audio Note (UK), or
carried out by persons other than appointed Audio Note (UK) service
engineers will invalidate any warranty.
This Warranty does NOT cover: -
Damage sustained whilst in the possession of a shipping agent, retailer or consumer
and not caused as a direct result of defects in materials or workmanship.
Damage caused by normal wear and tear.
Damage or defects caused by abnormal or unreasonable use.
Damage caused by accident, acts of nature, misuse or neglect.
Damage caused by a failure to follow the operating and installation instructions
supplied with the product.
Damage caused by improper or careless cleaning.
Audio Note (UK) reserves the right to refuse warranty for any component of which
the serial number has been removed, defaced or tampered with.
WARRANTY INFORMATION

Audio Note (UK) Limited
25 Montefiore Road
Hove
East Sussex
BN3 1RD
United Kingdom
Tel: [phone]
Fax: [phone]
e-mail: [email protected]o.uk
CONTACT INFORMATION
If in the future your Audio Note (UK) product
requires servicing, or if you require technical support
or have any questions regarding this or any of our
other products, please contact your local Audio Note
(UK) dealer.
Alternatively, please feel free to contact us directly: -!