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Impedance
With One or Two Subwoofers
When one or two CM8SW subwoofers are
connected to the satellite speakers, the
overall system impedance to the amplifier
lowers.
System Impedance in Ohms (Ω)
One or Two Subwoofers
8
Ω Sats 4Ω Sats
1 Sub 4
Ω 2.6Ω
2 Subs @8Ω each 4Ω 2.6Ω
2 Subs @4Ω each 2.6Ω 2Ω
If the impedance is too low for your ampli-
fier utilize a Niles speaker selector or IM
volume control to match the impedance.
VLSA (Four or More Subwoofers)
A VLSA (Very Large Subwoofer Array)
installation lowers the amount of excur-
sion required to achieve a high sound
pressure level. Lowering excursion dra-
matically improves the quality of the
sound. VLSA installations are most appro-
priate when the listener appreciates detail
and bass extension, but must have a con
-
cealed installation.
Each subwoofer should have its voice coils
connected in parallel for full output, there-
fore the impedance of each is four ohms.
Because of this low impedance, a multi-
channel amplifier stable to 4 ohms is the
best way to drive more than two sub-
woofers. Each CM8SW is connected to its
own channel of a multi-channel amplifier.
Check Your Amplifier’s Specs
Every amplifier has a minimum impedance
specifications. Check your owner’s manual
to determine whether or not your amplifier
is capable of driving a four ohm load. This
specification may also be noted on the rear
panel of the amplifier. If your amplifier is
not able to drive a four ohm load it may
only be used to power a CM8SW
satellite/subwoofer system when an imped-
ance magnifying volume control is incor-
porated into the system
An amplifier stable to four ohms may be
connected without impedance matching
devices. Parallel connections via the “A”
speaker terminals to one or two CM8SW
subwoofers (If the voice coils are not in par-
allel) and one pair of eight ohm satellite
speakers results in a four ohm load.
The “B” speaker terminals cannot be used
to power a second pair of speakers any-
more.
The low impedance drive capability
of your amplifier is already utilized by the
satellite/subwoofer combination. If you are
connecting other speakers in other rooms
you must install either a speaker selector or
impedance magnifying volume controls.
A few professional/audiophile amplifiers
advertise the capability of driving two
ohm speaker loads. These amplifiers may
be used without impedance matching
devices if the rating is quoted as “RMS” or
“Continuous” power and the amp does
not push too much power.
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Impedance