Rear Panel - Mackie HR824 Service Manual

REAR PANEL DESCRIPTION
SIGNAL INPUTS
• The XLR female and TRS female connectors
are connected in parallel .
• Both input connectors accept balanced or
unbalanced signals. They are wired as
follows (per the AES/IEC standard):
Hot (+)
Cold (–)
Shield (Ground)
INPUT SENSITIVITY CONTROL
• The HR824 expects a line-level signal at its
input connectors.
• The reference sensitivity is -7.5 dBu = 100 dB
SPL at one meter (39 inches) with the INPUT
SENSITIVITY control set to its NORMAL
position.
• The HR824 is designed to operate with a
+4 dBu signal when the INPUT SENSITIVITY
control is in the NORMAL position.
ACOUSTIC SPACE SWITCH
This is a three-way switch that adjusts the
low-frequency response of the speakers to
compensate for their placement in the
room.
• If you place the monitors against a wall
(half space ), set the ACOUSTIC SPACE
switch to the "B" position. This activates a
shelving filter to reduce the low-frequency
output by 2dB to compensate for the bass
boost from half-space placement.
• If you place the monitors into the corners
of your room (quarter space ), the low-
frequency output approximately doubles
from what it is in half space. Set the
ACOUSTIC SPACE switch to the "A" position
to reduce the low-frequency output by 4dB
to compensate for the bass boost.
• If you use the HR824s free-standing, away
from walls and corners (whole space ), set
the ACOUSTIC SPACE switch to the "C"
position (NORMAL).
6
XLR TRS
Pin 2 Tip
Pin 3 Ring
Pin 1 Shield
LOW FREQ SWITCH
• The LOW FREQ switch inserts a steep low-
frequency rolloff into the response curve.
• For most applications, use the 47Hz setting.
• If you want or need the extra low-frequency
capability, use the 37Hz (NORMAL) position.
• You can use the 80Hz position to simulate
a smaller loudspeaker.
HIGH FREQ SWITCH
• The HIGH FREQ switch tailors the overall
high-frequency response by ±2dB at 10kHz.
POWER MODE SWITCH
• In the OFF position, the power amplifiers
are in Standby mode and produce no
sound. Low-level circuitry is still active, but
the power consumption of the circuitry is
minimal (8 watts).
• In the ON position, the power amplifiers
are live and operate normally. (The front
panel ON/OFF switch must also be ON.)
• Since the power supply and low level
circuitry are already active (assuming the
speaker is plugged into a live outlet), this is
an "instant on" function.
• In the AUTO ON position, the amplifiers turn
on and off depending on the presence or
absence of an input signal. An input signal
level of –45dBu (minimum) activates the
auto-on function. A silent period greater
than five minutes activates the auto-off
function. The red PWR LED on the front
panel reflects the state of the amplifiers.
• Normally, use the front panel switch to turn
the monitors on and off.
• If you unplug the power when a signal is
still applied to the input, you may hear
sound from the monitor. This is after about
6 seconds, when the muting circuit
unmutes and the power supply finishes
discharging. This is normal and not harmful
to the monitor.
MAINS INPUT
• Connect the power cord to this IEC
socket, and plug the other end into your
AC outlet.
IMPORTANT: For safety reasons, the AC
source must be a "3-prong" outlet
with hot, neutral, and ground
terminals.
WARNING: Bypassing the plug's ground
pin can be dangerous. Don't do it!