ATC SCM20ASL Owner's Handbook Manual page 11

SCM20ASL LE
P r o d u c t D e s c r i p t i o n
The SCM20ASL Limited Edition is a compact 2-way
high-performance active loudspeaker, featuring the
ATC SB75-150SL Super Linear Bass/Mid driver and the
ATC SH25-76S 'S- spec' Dual suspension tweeter. The
bass driver operates in a 20-litre cabinet and the drivers
are powered by a dedicated 2-way active Class A-B
power amplifier, capable of delivering a combined 250W ,
to deliver exceptional clarity and dynamics.
This Limited Edition product is limited to just 150 pairs,
all finished with a high gloss polyester lacquer in the ATC
colour of Pantone 282 c and featuring silver anodised
metalwork and a hand wrapped Royal Blue leather baffle
from German leather specialists Eissmann Individual.
R o o m I n t e r a c t i o n
The room in which a loudspeaker is placed can be
thought of as a filter, altering the acoustic response at the
listening position from that of the loudspeaker. The
position of the loudspeaker in a room will influence how
it interacts with the space and therefore is often critical to
achieving the best performance at the listening position.
Speaker positioning is important because at low
frequencies the room will have a strong influence due to
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room modes/resonances. Room modes manifest optimum position for exciting room modes between
themselves in an uneven distribution of acoustic energy the mounting wall and the opposite wall. The
within the room, which can lead to either too much requirement for adequate bass trapping in the rear
or too little bass at the listening position. A room with wall in this instance can be even more critical.
a well-controlled low frequency response (controlled
L o u d s p e a k e r P l a c e m e n t
reverb time) will have a far smaller influence on the
performance of the loudspeaker and will be less sensitive
Typically, best results come from mounting the
to positioning. Applying acoustic treatment in a domestic
speakers on suitable speaker stands. Stands should be
setting is not always possible or desirable but if considered
heavy, rigid, and non-resonant. The stand height
it should be noted that, typically, a combination of
should be selected so that the speaker acoustic centre
resonant membrane traps and porous absorbers are
is at, or just above ear level (see diagram 1).
needed to control the low frequency. The resonant
Position the loudspeakers so they form an equilateral
membrane traps are effective at treating the low bass,
triangle with the listening position (see diagram 2).
typically below 80Hz and the porous absorbers
frequencies above this. Porous absorbers such as those With this layout, the distance between the loudspeakers
made from foams, fibreglass or rockwool are not effective will be equal to the distance from one speaker
to the listening position.
at absorbing low bass energy without a very large air
space between them and the wall behind which reduces
useable space within a room.
To minimise problems a free-standing loudspeaker should
be kept away from corners where possible. Avoid placing
the loudspeaker mid-way between any two parallel
walls. Where the loudspeaker is to be installed directly
into a heavy, rigid non-absorbent wall (flush/soffit
mounted), an increase in LF efficiency and LF extension
should be expected. In-wall loudspeakers are in the
A c o u s t i c a x i s
L. Spk
In
Pre-Ampli er
L. Pre-Out
P o s i t i o n l o u d s p e a k e r w i t h a c o u s t i c
a x i s a t o r u p t o 5 º a b o v e e a r l e v e l
R. Sub
L. Sub
In
In
L. Sub-Out R. Sub-Out
d i s t a n c e z
D i s t a n c e x = D i s t a n c e y = D i s t a n c e z
R. Pre-Out