SCM12 Pro User Manual
S C M 1 2
P r o
u s e r
m a n u a l
p r o
l o u d s p e a k e r
In selecting ATC you have chosen an example of the finest audio engineering available.
Since its very beginning ATC has kept steadfastly to its founders’ aim of building, mostly by hand,
loudspeakers which employ the most effective of modern engineering principles.
s e r i e s
and large dynamic range. There is therefore no differentiation technically between an ATC hi-fi product and
professional monitor other than the way it is packaged. A high fidelity loudspeaker is a high fidelity loudspeaker
whether it is for home or work.
That has meant striving to make loudspeakers as near perfection as it is possible to make them.
ATC is best known for its active professional Studio Control Monitors and in most cases this is the most economic
In order to get the very best from ATC equipment careful and thoughtful installation is essential,
and highest performance solution available to the professional engineer. Passive loudspeakers, however, still have their
so please read the manual fully to understand your ATC monitor and realize
the very best performance it has to offer.
Please contact ATC with any questions or issues that arise during installation
or use and we will do our very best to help.
place and offer an excellent alternative to active in small 2-way systems. The latest professional passive loudspeaker
in the ATC range is the SCM12 Pro which is perfectly partnered by the ATC P1 Pro, 150 watts/channel
professional power amplifier.
ATC is also a long established audio electronics manufacturer. It all started in 1982 with the EC23 stereo, 3 way
electronic crossover incorporating phase correction and momentary gain reduction which is pre-set to prevent
ATC (Acoustic Transducer Company) was founded in London in 1974 by Australian Billy Woodman who still heads
the company today. An enthusiastic jazz pianist and engineer he was naturally drawn to loudspeaker design.
After working for ROLA in Melbourne Billy, in 1970, travelled to England and worked in R&D at Goodmans in
the power amplifier from clipping at high drive levels and so protect the drive units.
This technology was incorporated into the 3 way Ampack developed for the SCM50A first produced in 1985.
ATC has been in continuous manufacture of electronic products ever since.
Wembley (the training ground of many well-known British loudspeaker engineers) before starting ATC.
The philosophy upon which ATC began the development of its studio products is a simple one: that at their best,
hi-fi loudspeakers are detailed and accurate but limited by dynamic range, whilst professional monitor loudspeakers
have plenty of dynamic range but lack the clarity and accuracy.
ATC bridged this gap by developing, in house, unique drive units of exceptionally low coloration performance
From modest beginnings ATC has grown to become one of the very few manufacturers successful across both
domestic and professional audio. By selecting ATC you join a group of music lovers, professional audio engineers,
educators, studios and musicians across the world that understand the value of the engineering that goes into
every ATC product.
1 : Description
3 : Unpacking & Handling
The SCM12 Pro is a high performance 2-way passive nearfield
monitor. The monitor is equipped with a "bi-wire" connection
care. Unpacking is best carried out on the floor or a large low
panel to enable separate amplification of mid/bass and high
table, with adequate open space around the carton, preferably
frequency drivers if required.
close to their final position.
In professional installations, try to avoid placing the loudspeakers
Up-end the carton so the open end is facing down.
2. Retain these instructions – the safety and operating
instructions should be retained for future reference.
3. Follow instructions – all operating and other instructions
Lift the carton off the contents (speaker & foam ‘end-caps’).
Lift the upper foam end cap off.
Lift each loudspeaker out of the foam end cap, remove from
the bag and position in the listening/control room.
5. Heat – the appliance should be situated away from heat
sources such as radiators, stoves or other appliances that
produce heat.
6. Cleaning – the appliance should be cleaned only as
recommended by the manufacturer.
7. Servicing – the user should not attempt to service the
appliance beyond those measures described in the operating
towards the back walls. If the balance is bass heavy try moving
If the balance is bass light the monitors can be moved
the monitors away from walls/corners.
#"!$ %
Stereo Listening. The loudspeakers should be positioned
(see Fig.1). Loudspeaker stand height should be chosen so the
Fig. 1
Stereo Loudspeaker Positioning
Fig. 2
Acoustic Axis
acoustic axis is at ear level (see Fig. 2). For most seating
positions in professional scenarios, a suitable stand would be
900 - 1000mm or 35.5 - 39.4" tall. Suitable stands should be
heavy, rigid and resonance free.
4 : Monitor Placement
If the loudspeakers have to be positioned so the acoustic axis is
to dripping or splashing and no objects such as vases, should
be placed on the appliance.
console/desk usually gives better results.
so they form an equilateral triangle with the listening position
should be followed.
4. Water and moisture - the appliance should not be exposed
mid range. Mounting the speakers on stands behind the
distance x = distance y = distance z
1. Read instructions – all the safety and operating instructions
should be read before the appliance is operated.
distance z
the frequency balance of the loudspeaker, especially in the lower
# !
packing foam in place.
Loudspeaker Positioning - Stereo
2 : S a f e t y Wa r n i n g s
Open the carton and remove all loose items, leaving the
on the console/desk meter bridge. Typically, this compromises
The SCM12 Pro is an heavy item and should be handled with
The subjective performance of any monitor loudspeaker will be
above ear level, they can be tilted downwards.
influenced by the acoustic character of the room in which it is
5.1 or 7.1 Surround Positioning. All loudspeakers should be
used and its position within the room. Most often, monitors are
equidistant from the listening position – see Fig. 3: distance
installed in rooms which are comfortable to sit and talk in.
L=C=R=LS=LR=RR=RS. For 5.1 systems, position the surround
A mixture of carpets, curtains and soft furnishings will help
speakers between110° and 150° degrees (ITU spec. is 110°). If
ensure that the middle and high frequencies are reasonably well
ideal positioning isn’t possible, position loudspeakers as close as
controlled. There may, however, be low frequency problems;
possible to ideal. Try to avoid placing subwoofers in corners, very
either too much or too little bass. To minimise low frequency
close to walls, and on the midpoint between two parallel walls
All rooms vary, and it is a good idea to experiment with both
instructions. All other servicing should be referred to
Try to position speakers away from walls
listening and speaker position until a good compromise is
qualified service personnel.
Try to position speakers away from corners
reached. For professional installations the requirements are often
Try not to position speakers exactly 1/4, 1/3, 1/2, 2/3, 3/4
very specific. Please consult an experienced professional
between parallel walls
acoustician if necessary.
Fig. 3
5.1 and 7.1 Surround Loudspeaker Positioning
5 : Connection
6 : Amplification
7 : Listening
There are no user-replaceable parts within the speaker and,
in the unfortunate event of any malfunction, repair should be
The SCM12 Pro monitor is equipped with a “bi-wire” connection
The choice of partnering amplifier for the monitors will have
The ear and brain tend to interpret distorted sound as loudness
referred to either the supplying dealer or consultant, the
panel to enable separate amplification of the bass/mid driver and
significant influence on the performance of the system. Consider
and thus underestimate the actual level of undistorted sound.
relevant importer, or ATC.
tweeter. The connection panel is shown in Fig. 4.
the following when selecting the amplifier:
The SCM12 Pro, like all ATC monitors, demonstrate very much
lower levels of distortion than conventional systems of a similar
With any passive loudspeaker there is a trade off between
If not bi-wiring, connect your speaker cable to either the upper
or lower horizontal pair of terminals. Should you wish to take
low frequency extension and sensitivity. These monitor’s
advantage of the bi-wire facility remove the linking bars, between
extended low frequency response means the sensitivity is
vertical pairs of terminals. The upper horizontal pair of terminals
relatively low. It is therefore advisable to select a power amplifier
are connected to the tweeter. The lower horizontal pair are
of relatively high power output capabilities. Typically, best
connected to the bass driver.
performance comes with use of amplifiers capable of >150W
Terminals can accommodate either stripped bare cable ends,
continuous into 8 ohms.
Use of an underpowered amplifier will result in the
it manufactures.
size. It is therefore advisable to begin listening at an artificially
low level and carefully increase the volume. It is also possible for
the SCM12 Pro to produce sufficient sound pressure levels for
9 : Specifications
your ears themselves to become a source of distortion and
make the sound appear harsh. Any audible distortion indicates
that either the system or your ears are being overloaded and
HF ATC 1˝/25mm dual suspension Soft Dome (SH25-76 6 Ohm)
LF ATC 6˝/150mm Constrained Layer Damping (CLD) (SB50-150CLD 8 Ohm)
that volumes should be reduced. The user should also bear in
mind that the monitoring level in a professional environment
4mm banana plugs or spade terminals. Do not use crimps on the
bare wire ends as the difficulty in compressing them can cause
premature distortion of the system and increased risk of damage
can change the way certain sounds are perceived and that for
poor link bar connection.
due to voice coil overheating
consistent high quality results, consistent and moderate
Always use a good quality speaker cable with 2.5mm2 minimum
cross sectional area per conductor (79 strand). For cable runs
should be auditioned carefully, to establish that their
longer than 5 metres use a significantly heavier gauge cable.
characteristic reduced damping factor at low frequencies is
Consult your dealer or consultant for specific cable
monitoring levels should be used.
Valve or solid state amplifiers with high output impedances
Amplitude Linearity
80Hz - 16kHz (+/-2dB)
Cut Off Frequencies
56Hz - 22kHz (-6dB freestanding)
8 : Care & Maintenance
±80° Coherent Horizontal, ±10° Coherent Vertical
Maximum Continuous SPL
High technology material finishes are used in this product.
ATC has every confidence in the quality of each product that
The surfaces are durable and with a little care can be kept as
Ensure that the positive and negative terminals on each
good as new even under conditions of heavy use. Normally, a
connection panel are connected to the corresponding positive
dry duster will be all that is required to keep the finishes clean.
108dB (per pair @ 1m)
Crossover Frequency
Recommended Power Amplifier
75 to 300 Watts
and negative terminals on the amplifier.
A lack of bass output and very wide unstable stereo image is
most likely caused by the left and right loudspeakers being
connected out of phase. If the system displays these
characteristics, please check the polarity of the wiring.
Fig. 4
SCM12 Pro Passive Input Panel
Heavy soiling can be cleaned using a cloth slightly moistened
Nominal Impedance
with a non-abrasive household cleaner.
8 Ohm
There are no components within the speakers that can be
considered expendable, or that would benefit from regular
Binding Posts/4mm Plugs, bi-wire
maintenance. There is no requirement for any kind of routine
Cabinet Dimensions (HxWxD)
service work and there is no schedule for preventative
Weight : 11kg/24lbs (per cabinet)
1 0 : Wa r r a n t y & C o n t a c t
All ATC products are guaranteed against any defect in materials or workmanship
for a period of two years from the date of purchase.
Within this period we will supply replacement parts free of charge
provided that the failure was not caused by misuse, accident or negligence.
Purchasers who complete and return the Warranty Card
will have their warranty period extended up to a period of six years
from the date of purchase.
This guarantee does not limit statutory rights.
Loudspeaker Technology Ltd Gypsy Lane, Aston Down, Stroud, Gloucestershire GL6 8HR United Kingdom
Telephone +44 (0)1285 760561 Fax +44 (0)1285 760683
Email: Website:
Acoustic Transducer Company is the trading name and
is the registered trade mark of Loudspeaker Technology Ltd.
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