Protection Circuits

There are several protection mechanisms designed into the SRM1801 to safeguard the subwoofers and amplifiers from inadvertent damage.

CAUTION: The protection circuits are

designed to protect the subwoofers under

reasonable and sensible conditions. Should you choose to ignore the warning signs

(i.e., frequent OL LED indications, excessive distortion), you can still damage the speakers in the SRM1801 by overdriving them 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.

Placement

The SRM1801 subwoofer is designed to sit on the floor or stage. It is not designed to be pole-mounted or suspended.

When pole-mounting loudspeakers, be sure that the SRM1801 subwoofers are stabilized and secured from falling over or being accidentally pushed over. For stacked scenarios, it is highly suggested that straps are utilized. Failure to follow these precautions may result in damage to the equipment, personal injury, or death.

WARNING: The cabinet has no rigging points and is not suitable for rigging. NEVER attempt to suspend the SRM1801 by its handles.

As with any powered components, protect them from moisture and extreme cold and follow the other Care and Maintenance suggestions below.

Overexcursion Protection

A 12 dB/octave high-pass filter at 40 Hz just prior to the low-frequency amplifier prevents very low frequencies from being amplified. Excessive low- frequency energy below 40 Hz can damage the woofer by causing it to “bottom out,” also known as overexcursion, which is equivalent to a mechanical form of clipping.

Thermal Protection

All amplifiers produce heat. The SRM1801 is designed to be efficient both electrically and thermally.

The amplifier module is mounted on a large heatsink, which is cooled by convection where cool air is drawn over the rear panel, carrying the heat away. In order for this convection cooling to work efficiently, it is important to provide adequate airspace behind the subwoofer. When you position the SRM1801, we recommend leaving at least six inches of air space behind it.

If for some reason the internal temperature gets too hot, a built-in thermal switch activates and turns down the amplifier. When the amplifier cools down to a safe temperature, the thermal switch resets and normal operation resumes. If the internal temperature again gets too hot, the output level reduction process repeats. Should this happen, make sure that airflow to the rear of the cabinet is not restricted.

Care and Maintenance

Your Mackie subwoofers will provide many years of reliable service if you follow these guidelines:

Avoid exposing the subwoofers to moisture. If they are set up outdoors, be sure they are under cover if rain is expected.

Avoid exposure to extreme cold (below freezing temperatures). If you must operate the subwoofers in a cold environment, warm up the voice coils slowly by sending a low-level signal through them for about 15 minutes prior to high-power operation.

Use a dry cloth to clean the cabinets. Only do this when the power is turned off. Avoid getting moisture into any of the openings of the cabi- net, particularly where the driver is located.

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