PROTECTION CIRCUITS CONNECTIONS

There are several protection mechanisms designed into the HRS120 to safeguard the loudspeaker and amplifier from inadvertent damage.

Peak Limiter

A peak limiter is located at the input to the power amplifier section. It monitors both the amplifier output signal and the power supply voltages to guard against clipping and overloading the amplifier. This allows for loud and punchy bass performance without distortion, ensuring long-term reliability.

Thermal Protect

All amplifiers produce heat. The HRS120 is designed to be efficient both electrically and thermally.

•If for some reason the heatsink or power transformer gets too hot, a thermal switch activates, placing the HRS120 into Standby mode.

•Should this happen, make sure that airflow to the rear of the cabinet is not restricted.

•When the heatsink or power transformer cools down to a safe temperature, the switch resets and normal operation resumes.

Note: The POWER LED remains lit if the thermal protection circuit is activated.

Input and Output Signal Wiring

You should use high-quality, shielded cable to connect the signal source to the LEFT and RIGHT IN and OUT jacks on the HRS120.

•Foil shielded cables, such as Belden 8451, 8761, or 9501 are commonly used for studio wiring.

•Microphone cables work well.

•The better the shield, the better the immunity from externally induced noise (like EMI and RFI). Route the cable away from AC power cords and outlets. These are common sources for hum in an audio signal. Wall warts and line lumps are especially insidious hum inducers!

You can purchase quality cables from your Mackie dealer.

•In certain home theater applications, it may be necessary to connect the speaker outputs from a stereo receiver to the inputs of the HRS120s, if the receiver doesn’t have preamp outputs or other line-level output connections.

CAUTION: Do not attempt to connect a speaker output directly to the input of the HRS120! Speaker levels are much higher than line

levels and can damage the input circuitry in the HRS120.

You can, however, insert a speaker-level to line-level signal attenuator between the receiver’s speaker output and the HRS120’s input. Your Mackie dealer may be able to help you find one, or you can build your own. Contact our tech support department for more information.

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