Installation manual
9
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Installation
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Installation Manual
9-14
Audio System Impedance
All loudspeakers have an impedance rating measured
in Ohms. The typical impedance rating for speakers is
between 4 and 8 Ohms. Amplifiers also have an output
impedance rating, usually no lower than 4 Ohms and no
higher than 16 Ohms. This means the total speaker
“load” must be no lower than 4 ohms and no higher
than 16 ohms. When speakers are connected in paral-
lel (the “+” terminals are connected to the “+” terminal
of the next speaker, the terminals are connected simi-
larly to each other, and then again similarly to the am-
plifier), their impedance is cut in half. Two 8 Ohm speak-
ers become a single 4 Ohm load.
Because a stereo amplifier is really two separate mon-
aural amplifiers comprising left and right channels, the
principle applies with speakers in pairs—two left 8
Ohm speakers become a 4 Ohm load on the left am-
plifier channel, and two right 8 Ohm speakers become
a 4 Ohm load on the right amplifier channel.
✍
Take Note: One exception to the normal 4-16 Ohm im-
pedance rating for an amplifier is a public address (“PA”)
type amplifier used in paging and background music sys-
tems. These use transformers to overcome impedance-
matching problems, but audio transformer designs are rarely
encountered in home audio systems.
As a result, if you are connecting anything more than 2
speaker pairs you must take steps to keep the imped-
ance between 4-16 Ohms. Running anything below 4
ohms or above 16 ohms can cause amplifier damage.
To avoid amplifier damage when connecting between 3
and 6 pairs of speakers, do one of the following:
• Insert an impedance-matching device such as an im-
pedance matched volume control (P/N 40901-D*) be-
tween each speaker pair and the Audio Bridging
Module
• Insert a separate impedance-matching audio com-
ponent between all speaker pairs and the Audio
Bridging Module, usually as a “loop” back to the en-
tertainment center or A/V receiver
This manual only covers the first of these two options.
The second option will depend on the design and con-
nection of the numerous devices on the market.
Connecting the Audio Bridging Module
Just as when you’re working with AC circuits, it’s im-
portant to shut down your power source before working
on low-voltage wiring. In the case of connecting to the
Audio Bridging Module, you must shut down the audio
system amplifier before making any connections.
For more information call your Leviton representative or the Leviton Technical Hotline at 800-722-2082
© Copyright 2000 Leviton Manufacturing Co., Inc.
R+
R-
L+
L-
R+
R-
L+
L-
R+
R-
L+
L-
R+
R-
L+
L-
R+
R-
L+
L-
R+
R-
L+
L-
R+
R-
L+
L-
SPEAKER CONNECTION MODULE
Room 1 Room 2 Room 3 Room 4 Room 5 Room 6
From Amp
Max 140
Audio Amplfier
Speaker Outputs
R+ R-L+ L-
R+
R-
L+
L-
QuickPort Wall Plate
with Binding Banana
Jacks
OUTPUT
INPUT
L- R+L+ R- R+
L-
L+ R-
ANALOG VOLUME
CONTROL
2 Ea. Stranded
14/2 Cable
Left
Right
Multi-Room Stereo -
Analog Volume Controls and Audio Bridging Module