Thermal Protect

All amplifiers produce heat. The HR824 is designed to be efficient both electrically and ther- mally.

•If for some reason the heatsinks get too hot, a thermal switch activates, placing the

HR824 into Standby mode (indicated when the red PWR LED turns off).

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

•When the heatsinks cool down to a safe temperature, the switch resets and normal operation resumes.

INTEGRATED MAGNETIC SHIELDING

The HR824 Studio Monitor contains drivers with large magnet 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.

INPUT SIGNAL WIRING

You should use high-quality, shielded cable to connect the signal source to the SIGNAL INPUT jack on the HR824.

•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 HR824s, if the receiver doesn’t have preamp outputs or other line-level output connections.

You can either make or purchase a speaker- level to line-level attenuator to reduce the signal from the receiver’s speaker output so it can be connected to the HR824’s input. The following illustrations show how to make an attenuating pad for the balanced XLR and TRS connectors. Use a 330 ohm resistor (R2) for a 30 dB pad, and a 620 ohm resistor (R2) for a 25 dB pad. This attenuator can be used safely with amplifi- ers rated up to 500 watts into 8 ohms.

From Speaker Output

 

 

 

 

 

From Speaker Output

 

 

 

 

of Receiver

 

 

R1

 

 

of Receiver

RING SLEEVE

SLEEVE RING

TIP

 

 

(10K

 

 

 

SHIELD

 

2 .5W)

 

 

 

 

 

 

 

 

HOT

 

 

 

 

 

 

 

 

 

 

 

 

 

 

TIP

R1

 

R2

1/4"

 

COLD

3

R2 1

 

 

3-Conductor Cable

(10K

(330Ω .25W for –30 dB)

TRS Plug

 

 

 

 

.5W)

 

or

3-Conductor Cable

(330Ω .25W for –30 dB)

 

 

 

(620Ω .25W for –25 dB)

 

 

 

 

 

 

 

 

(620Ω

or

 

 

 

 

 

 

 

 

.25W for –25 dB)

 

 

 

 

 

 

From Speaker Output

R1

 

Shield

 

From Speaker Output

R1

SHIELD

 

 

 

 

 

SLEEVE (SHIELD)

of Receiver

(10K

 

 

 

 

of Receiver

(10K

 

.5W)

 

 

2

1

.5W)

 

 

 

 

 

 

 

 

 

+

 

 

 

+

 

 

 

TIP (HOT)

 

 

 

 

 

 

 

 

–

 

 

 

3

 

–

 

 

 

RING (COLD)

 

 

 

 

 

 

 

1/4"

3-Conductor Cable

Ω

R2

 

Male

3-Conductor Cable

Ω

R2

 

 

(330 .25W for –30 dB)

XLR

 

 

(330 .25W for –30 dB)

TRS Plug

 

Ω

or

 

 

 

Ω

or

 

 

(620 .25W for –25 dB)

 

 

 

(620 .25W for –25 dB)

 

Figure 3. Speaker-level to Line-level XLR Pad

 

Figure 4. Speaker-level to Line-level TRS Pad

 

13