Protection Circuitry; Limiting; Overexcursion Protection; Thermal Protection - Mackie Thump 12 Owner's Manual

Protection Circuitry

Thump loudspeakers employ a built-in limiter for
less distortion at peak levels. A dynamic bass response
circuit provides optimal low frequency response
regardless of overall output level. Additional protection
includes automatic thermal shutdown should the amp
overheat. However, with Class-D amp technology, which
is highly-efficient, this should never be a problem.
The protection circuits are designed to
protect the loudspeakers under reasonable
and sensible conditions. Should you choose
to ignore the warning signs [e.g. excessive distortion],
you can still damage the speaker in the loudspeaker
by overdriving it past the point of amplifier clipping.
Such damage is beyond the scope of the warranty.

Limiting

The driver has its own compression circuit which
helps protect it from damaging transient peaks.
The compressor is designed to be transparent and
is not noticeable under normal operating conditions.

Overexcursion Protection

A subsonic filter circuit just prior to the power ampli-
fier prevents ultra-low frequencies from being amplified.
Excessive low-frequency energy can damage the woofer
by causing it to "bottom out," also know as overexcur-
sion, which is equivalent to a mechanical form of clip-
ping.
12
Thump12 • Thump15 Powered Loudspeakers

Thermal Protection

All amplifiers produce heat. Thump loudspeakers are
designed to be efficient both electrically and thermally.
In the unlikely event of the amplifier overheating,
a built-in thermal switch will activate, muting the
signal.
When the amplifier has cooled down to a safe
operating temperature, the thermal switch resets
itself, and the Thump loudspeaker resumes normal
operation.
If the thermal switch activates, try turning down
the level control a notch or two on the mixing console
(or the back of the loudspeaker) to avoid overheating
the amplifier. Be aware that direct sunlight and/or
hot stage lights may be the culprit of an amplifier
overheating.

AC Power

Be sure the Thump loudspeaker is plugged into
an outlet that is able to supply the correct voltage
specified for your model. It will continue to operate
at lower voltages, but will not reach full power.
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
a cleaner, punchier bass. A suspected problem of "poor
bass performance" is often caused by a weak AC supply
to the amplifiers.
Never remove the ground pin on the power
cord or any other component of the Thump
loudspeaker. This is very dangerous.