Impedance
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
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
