Niles Audio PSW8 - Manual (Page 8)

Impedance
With One or Two Subwoofers
When one or two PSW8 subwoofers are
connected to the satellite speakers, the
overall system impedance to the amplifier
lowers.
System Impedance in Ohms (Ω)
One or Two Subwoofers
8Ω Sats 4Ω Sats
1 Sub 4Ω 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 installation lowers the amount of
excursion required to achieve a high
sound pressure level. Lowering excursion
dramatically 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,
therefore the impedance of each is four
ohms. Because of this low impedance, a
multi-channel amplifier stable to four
ohms is the best way to drive more than
two subwoofers. Each PSW8 is connected
to its own channel of the multi-channel
amplifier.
Check Your Amplifier’s Specs
Every amplifier has a minimum impedance
specification. Check your owner’s manual
for the specification for four ohm low
impedance drive capability. If there is no
clear indication and your amplifier or
receiver has two sets of speaker terminals
(typically labeled “A” and “B”) your ampli-
fier may be capable of driving a four ohm
load. Perform the following test to be sure:
Parallel/Serial Speaker Connection Test
1. Hook up one pair of speakers to the “A”
speaker terminals of your amplifier.
Leave the “B” terminals unconnected to
speakers.
2. Engage both the “A” and the “B”. Listen
for sound.
If your amplifier plays sound when “A”
and “B” are engaged, it is capable of dri-
ving a four ohm speaker load. If your
amplifier does not play sound when “A”
and “B” are selected, it is only capable of
driving an eight ohm speaker load. An
eight ohm stable amplifier may only be
used with a PSW8 satellite/subwoofer sys-
tem by installing an impedance magnify-
ing volume control.
An amplifier stable to four ohms may be
connected without impedance matching
devices. Parallel connections via the “A”
speaker terminals to one or two PSW8 sub-
woofers (If the voice coils are not in paral-
lel) 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.
7
Impedance