MACKIE SA1521 - Manual (Page 6)

6
THERMAL
CONSIDERATIONS
The SA1521 has two powerful built-in
amplifiers capable of producing a combined
500 watts of power. As amplifiers produce
heat, it is important to dissipate the heat as
quickly as possible. This results in increased
reliability and longevity for the amplifier.
The amplifier module is mounted on a
large heatsink, which is cooled by convection
where cool air is drawn through it’s fins, car-
rying the heat away. In order for this
convection cooling to work efficiently, it is
important to provide adequate airspace be-
hind the loudspeaker. When you position the
SA1521, we recommend leaving at least six
inches of air space behind it.
In the unlikely event of the amplifier over-
heating, a built-in thermal switch will
activate, which mutes the signal and lights
the
THERMAL LED. When the amplifier has
cooled down to a safe operating temperature,
the thermal switch resets itself, and the
SA1521 resumes normal operation.
If the thermal switch activates frequently,
try turning down the level control a notch or
two on the mixing console (or the back of the
SA1521) to avoid overheating the amplifier.
If the temperature in the room is too high,
it could cause the amplifier to overheat. In
this case, you should try aiming a fan at the
rear panel to move more air through the fins.
age specified for your model. If the voltage
should drop below 97% of the specified line
voltage, the built-in amplifiers will no longer
be able to supply rated power. (They will
continue to operate down to 80% of the
rated line voltage, but won’t reach full power,
resulting in lower headroom.)
Be sure the electrical service can supply
enough amperage for all the components
connected to it.
We recommend that a stiff (robust) supply
of AC power be used because the amplifiers
place high current demands on the AC line.
The more power that is available on the line,
the louder the speakers will play and the
more peak output power will be available for
cleaner, punchier bass. A suspected problem
of “poor bass performance” is often caused
by a weak AC supply to the amplifiers.
CAUTION: Never remove the ground pin
on the power cord of the SA1521 or any
other component. This is very dangerous.
There is also a male XLR connector la-
beled LOOP OUT. This is also wired
according to the AES standard.
The LOOP OUT connector allows you to
connect more than one SA1521 to your sys-
tem. Simply plug the signal source (i.e.,
mixer output) into the first
MAIN INPUT
jack, and patch that speaker’s LOOP OUT
jack to the next MAIN INPUT jack, and so
on, daisy-chaining multiple speakers.
The LOOP OUT jack is wired straight
from the MAIN INPUT connector — there is
no electronic circuitry between — so the
signal coming out of the
LOOP OUT jack is
exactly the same as the signal going in.
PLACEMENT
The SA1521 speaker is designed to sit on
the floor or stage. It can be pole-mounted via
the built-in socket on the bottom of the cabinet.
Be sure the pole is capable of supporting the
100 lbs. weight of the SA1521.
WARNING: The cabi-
net has no rigging
points and is not suit-
able for flying. NEVER
attempt to suspend the
SA1521 by its handles.
You can create a horizontal array by plac-
ing the cabinets side-by-side. However, you
should have a good understanding of the re-
lationship between the splay angle (the
angle between the facing sides of the cabi-
nets), the on-axis power, and frequency
cancellation effects between cabinets.
When two cabinets are placed side-by-
side, the actual splay angle is 20º (determined
by a 10º angle on each cabinet side). As the
splay angle increases toward the angle of
horizontal coverage (75º for the SA1521),
the on-axis power decreases, but the fre-
quency response becomes smoother as the
comb-filtering effects (caused by the interac-
tion in the area of double-coverage) decrease.
As with any powered
components, protect
them from moisture. If
you are setting them up
outdoors, make sure
they are under cover if
you expect rain.
AC POWER
Be sure the SA1521 is plugged into an
outlet that is able to supply the correct volt-