Audio Note M6 RIAA Technical manual

M6 Line
Owner’s Information
The M6 Line is a Level 4line pre-amplifier, developed
for the best possible sonic performance rather than
technical specifications. To this end, the M6 Line
incorporates thermionic valve technology to produce the
most accurate sound possible and has been brought to
maturity through a development process we call
comparison by contrast, which is currently unique to
Audio Note. The article from which this technique is
based, named ‘Audio Hell’, is available from Audio
Note by request.
Please read this manual carefully in order to obtain the
best possible performance from your pre-amplifier.
Audio Note wishes you many happy years of listening
pleasure.

Technology
It is well known to any audio circuit designer worth their salt that accurate
reproduction of music, not just sound, but music, relies entirely on the preservation of
the purity of the incoming signal. It is therefore not a difficult step to make to realise
that the complexity of the circuitry itself must be kept to a minimum in order to retain
the musicality of the original performance.
In response to this, all Audio Note pre-amplifiers use a single-ended, zero feedback
circuit topology.The single-ended gain stage topology is simply the most linear,
demanding pure Class A valve operation and removing the need for a phase splitter,
which introduces unnecessary crossover distortion.
The Audio Note amplifier range does not make use of any kind of feedback. As a
result, they were neither designed for vanishingly small harmonic or low
intermodulation distortions, but instead for minimal non-harmonic and time base
anomalies. It is these non-harmonic amplitude and time base distortion that have a
highly perceptible and adverse affect on the signal waveform.
Our amplifiers are designed for maximum linearity without ‘corrective’ measures to
keep transient distortions to a minimum rather than introducing the recursive errors
inherent in feedback loops.
The M6 Line features an ECC82 and 7044 line stage, a 6X5 valve rectified power
supply based on the M10’s Galahad PSU, silver wiring, tantalum resistors, Black
Gate filter capacitors, and Audio Note copper foil signal capacitors, HiB 50% nickel
c-core copper primary, silver secondary output transformers and a balanced output.
Unpacking & Installation
Please take care when unpacking the pre-amplifier. We recommend that you store the
packing materials in case the unit requires shipping at a later date.
Next, select a suitable location for the unit, ensuring that adequate ventilation is
provided (the valves generate a fair amount of heat). In the interest of safe, reliable
operation, situate the pre-amplifier well away from dampness or direct sunshine.
Avoid sitting the M6 Line close to any other equipment, such as a power amplifier,
that may be generating a strong magnetic field, or in close proximity to active mobile
telephones.
Worthwhile sonic improvements may be obtained by locating the unit on a
specifically designed audio component support system; we tend to prefer natural
materials such as wood.
The M6 Line is capable of driving long interconnects to power amplifiers and so, if
you are using mono block amplifiers, it may be worthwhile to locate them close to the
speakers. This will reduce the speaker cable lengths and provide sonic improvements.

Connections
Please ensure that the M6 Line, the power amplifier and any source equipment is
switched off before making any connections.
NOTE: It is important that all connections are firm, secure and airtight; any
oxidisation of the interconnects will result in loss of performance. Always use high
quality interconnects; Audio Note interconnects are recommended, as they are
manufactured to the same exacting standards as all of our products.
Inputs
The M6 Line offers four standard unbalanced line inputs and a tape input. All of these
are suitable for connecting to any line level source equipment such as a CD/DVD
player or a dedicated phono stage for a turntable.
The inputs each consist of a pair of RCA connectors, one red and one white, for right
and left channels respectively.
Outputs
The M6 Line provides two unbalanced outputsand a tape output. Again, all of these
outputs consist of a pair of colour coded RCA connectors. In addition, the M6 Line
also includes a balanced output, consisting of a pair of XLR connectors.
The two main outputs are for connection to a power amplifier and are identical,
making them suitable for biwiring. The balanced output can be used for low noise
connection to a power amplifier with a balanced input. The balanced and unbalanced
outputs cannot be used simultaneously; select the appropriate output using the toggle
switch.
The tape output is routed directly from the input selection switch; this provides a
suitable level for recording. The tape input is not routed to the tape output.
Ground Post
A ground connection is provided to assist in the elimination of any ground loops that
may occur. A ground loop can be identified by excessive background hum. If you
experience a ground loop, try connecting the ground connection with that of other
system components. If the hum persists, contact your dealer.
Mains Power
An IEC power connector is located on the back of the M6 Line. Use the supplied
power cable to connect the pre-amplifier to the mains supply. Ensure the power is off
at the switch when you do this.

Using the M6 Line
Once all the connections are completed and checked, make sure all power amplifiers
are off and flip the mains rocker switch located on the back panel of the pre-amplifier
to the 'on' position.
The M6 Line is a vacuum tube design and therefore requires about 45 seconds warm-
up time. After this the remaining system components may be turned on.
NOTE: Always turn the pre-amplifier on before turning on the power amplifier and
always turn the power amplifier off before turning off the pre-amplifier. This will
prevent any buzzing or popping sounds from occurring.
In order to use the line inputs, select 'source' and the appropriate input. To listen to a
tape select 'tape', the position of the source selector will not affect the output when
'tape' is selected. The volume control adjusts the overall output level of the pre-
amplifier while the balance control can be used to correct minor imbalances in the
stereo image. The balance control provides 9dB of attenuation for each channel. It
will not reduce the volume of either channel to zero.
The M6 Line will improve over time and will start to sound increasingly well
balanced. This is because of the “bedding in” time taken by new electrical
components inside the unit. Also, the pre-amplifier’s sound quality improves as the
unit reaches its normal, stable operating temperature. Only a rear panel on/off switch
is provided as the unit is designed for continuous operation. The M6 Line need not be
switched off each time after use. It is interesting to note that continuous operation not
only results in optimum sonic performance (since the unit is maintaining a constant
operating temperature) but also causes less electrical stress and so extends component
and valve life.

Cleaning
Cleaning the pre-amplifier is best done with a soft brush -some photographic stores
are able to provide suitable brushes. Alternatively, a soft cotton cloth may be used
with a mild propriety cleaner for removing dirt build-up. Strong or alcohol based
solvents may damage the finish of this product. Ensure the pre-amplifier is switched
off and cold when cleaning. Do not wet the unit.
Replacing and Upgrading the Valves
Replacement NOS valves can be purchased from Audio Note when valves fail or
should you wish to experiment with different types of valves. A list of valves and
equivalents can be found at www.audionote.co.uk. Contact your dealer if you are
unsure what valves you should use or how to install them.
Line stage valves should provide you with 5 years of continuous operation, rectifier
valves should last much longer.

Warranty and Servicing
Audio Note warrants that this product will be free from defects in materials and
workmanship for one year from the original date of purchase from an appointed
Audio Note dealer. The valves are warranted for three months.
In the event that your Audio Note product requires servicing, please contact your
Audio Note dealer. If the component needs to be shipped, please use the original
packaging materials and include a copy of the sales purchase with a note, explaining,
in as much detail as possible, the problems that your are experiencing with the unit.
Any modification not authorised by Audio Note will invalidate any warranty.
If you require technical support or have any questions, please direct them to your
local Audio Note dealer or alternatively contact us directly at:
Customer Support
Audio Note (UK) Limited
25 Montefiore Road
HOVE
East Sussex
BN3 1RD
United Kingdom
TEL: [phone]
FAX: [phone]
EMAIL: [email protected]
Specifications
Weight 16kg
Dimensions 135(h) x 440(w) x 410(d) mm
Max Power Consumption 81W
Fuse Ratings 1A anti-surge (110/120 V supply)
500mA anti-surge (220/240 V supply)
Input Impedance 100kO
Gain @ 1kHz 18dB
Input Sensitivity (for 1V output) 126mV
Output Noise (rms) < 0.08mV, unweighted
Output Impedance < 10O
Tube Compliment 1x ECC82, 1x 7044, 2x 6X5, 2x ECL82, 1x OB2
NOTE: Due to Audio Note’s ongoing research and development programme,
specifications are due to change without notice.

Safety Information
HEAT: By the nature of vacuum tubes, this product generates high levels of
heat. Adequate ventilation must be provided. Do not restrict the airflow
through any of the ventilation slots or place the amplifier on any surface that
may restrict airflow.
CAUTION: The vacuum tubes and other nearby parts operate at extremely
high temperatures -KEEP OUT OF REACH OF CHILDREN.
HUMIDITY: Do not store or operate this unit in areas of high humidity or in
close proximity to water. Do not expose the unit to liquid.
EARTHING: The product must be earthed -ensure that the mains supply cable
is earthed.
SAFETY COMPONENTS: Internal fuses and other safety components are
located inside this unit in accordance with BS 60065 requirements. In the
event of component failure, replacements must be of the same part type. Such
replacements must be carried out by a qualified service technician.
SHOCK: Internal operating voltages are lethal. Do not remove the top cover.
Do not replace fuse without first disconnecting the unit from the mains
supply.
This product complies with CE standards