5
Safety Issues
Pay close attention to these important electrical and
safety issues.
Use a power cord adapter to drive the MSL-6
from a standard 3-prong outlet
(NEMA 5-15R;125 V max).
earth
ground
chassis
ground
The MSL-6 requires a grounded outlet. Always
use a grounding adapter when connecting to
ungrounded outlets.
Do not use a ground-lifting adapter or cut the AC
cable ground pin.
Keep all liquids away from the MSL-6 to avoid hazards
from electrical shock.
Do not operate the unit if the power cables are frayed or
broken.
Tie-wrap anchors on the amplifier chassis provide strain
relief for the power and signal cables. Insert the plastic
tie-wraps through the anchors and wrap them around
the cables.
Audio Input
The MSL-6 presents a 10 k
Ω
balanced input impedance to
a three-pin XLR connector wired with the following
convention:
Pin 1
— 220 k
Ω
to chassis and earth ground (ESD clamped)
Pin 2
— Signal
Pin 3
— Signal
Case
— Earth (AC) ground and chassis
Pins 2 and 3 carry the input as a differential signal; their
polarity can be reversed with the input polarity switch
on the user panel. If the switch is in the up position,
pin 2 is hot relative to pin 3, resulting in a positive
pressure wave when a positive signal is applied to pin 2.
Use standard audio cables with XLR connectors for
balanced signal sources.
TROUBLESHOOTING NOTE:
Shorting an input connector
pin to the case can form a ground loop and cause hum.
If other abnormal noises (hiss, popping) are produced
from the loudspeaker, disconnect the audio source from
the speaker. If the noise stops, then the problem is not
within the loudspeaker; check the audio input and AC
power.
A single source can drive multiple MSL-6s with a paral-
leled input loop, creating an unbuffered hardwired loop
connection. Make certain that the source device can
drive the total load impedance presented by the paral-
leled input circuit. For example, since the input imped-
ance of a single MSL-6 is 10 k
Ω
, cascading 20 units
produces a balanced input impedance of 500
Ω
. If a 150
Ω
source is used, the 500
Ω
load results in a 2.28 dB loss.
Differential Inputs
