Thermal Considerations

The HD1221 has two powerful built-in amplifiers capable of producing a combined 600 watts of rms power. As an amplifier works, it produces heat. The higher the signal level, the louder and hotter it gets. 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 its fins, carrying the heat away. In order for this convection cooling to work efficiently, it is important to provide adequate airspace behind the loudspeaker. Additionally, a thermally-controlled fan resides inside of the HD1221 which helps to reduce the chance of it overheating and thermalling. When positioning the HD1221, we recommend leaving at least six inches of air space behind it.

In the unlikely event of the amplifier overheating, a built-in thermal switch will activate, muting the signal, lighting the thermal LED, and ramping the fan up to top speed. When the amplifier has cooled down to a safe operating temperature, the thermal switch resets itself, and the HD1221 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 HD1221) 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 HD1221 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 HD1221. This is very dangerous.

Care and Maintenance

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

•Avoid exposing the loudspeakers 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 loudspeakers 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 cabinet, particularly where the drivers are located.

Manual Owner’s

Owner’s Manual

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