MR5mk2

Protection Circuits

There are several protection mechanisms designed

 

 

into the MR5mk2 to safeguard the loudspeakers and

 

amplifiers from inadvertent damage.

 

 

CAUTION: The protection circuits are

 

 

 

 

designed to prevent damage to the

 

 

loudspeakers under reasonable and sensible

 

 

 

conditions. Should you choose to ignore the warning

 

signs (i.e., excessive distortion), you can still damage

 

the speakers in the MR5mk2 by overdriving them. Such

 

damage is beyond the scope of the warranty.

Overexcursion Protection

A 12 dB/octave high-pass filter at 50 Hz just prior to the low-frequency amplifier prevents very low frequencies from being amplified. Excessive low-frequency energy below 50 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 MR5mk2 is designed to be efficient both electrically and thermally.

•If for some reason the heatsink gets too hot, a thermal switch activates and turns off the amplifier. This protection operates independently for the low-frequency and high-frequency amplifiers. Therefore, it is possible for only the low frequency or high frequency amplifier to shut down while the other remains on.

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

•If the heatsink temperature again gets too hot, the shutdown process repeats. Should this happen, make sure that airflow to the rear of the cabinet is not restricted.

Integrated Magnetic Shielding

The MR5mk2 contains drivers with large magnetic structures. The drivers’ magnets are shielded to help prevent the magnetic field from radiating out into the environment and playing havoc with computer monitors or TV screens. Unshielded speakers can cause distortion in both the shape and color of the picture

if placed too close to a CRT (cathode ray tube). If you have a particularly sensitive computer monitor or TV screen, it may be necessary to move the speakers a few inches away.

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MR5mk2

Input Signal Wiring

You should use high-quality, shielded cable to connect the signal source to the signal input jack [1] on the MR5mk2.

•For balanced signals, foil shielded cables, such as

Belden 8451, 8761, or 9501 are commonly used for studio wiring.

•Microphone cables work well for the XLR input.

•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! Quality cables may be purchased from Mackie dealers.

•In certain home theater applications, it may be necessary to connect the speaker outputs from a stereo receiver to the inputs of the MR5mk2, 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

MR5mk2! Speaker levels are much higher than line levels and can damage the input circuitry in the MR5mk2.

However, it is possible to insert a speaker-level to line-level signal attenuator between the receiver’s speaker output and the MR5mk2’s input. The local Mackie dealer should be able to assist, or you can build your own.

Care and Cleaning

Mackie Reference Studio Monitors will provide many years of reliable service if you follow these guidelines.

•Avoid exposing the monitors to moisture.

•Avoid exposure to extreme cold (below freezing temperatures).

•Use a dry cloth to clean the cabinets. Only do this when the power is turned off.