by Jeff Fisher
This application note presents a few pointers and options on wiring remote speakers for a whole-house audio system. The details of any system depend greatly upon the actual signal sources, amplifiers, and control systems selected. The one aspect that tends to remain constant regardless of the equipment used is speaker wiring.
The most common configuration for speaker wires is the "home run." This is where most of the equipment is in a central equipment room and each remote speaker wire runs from there to the speaker location.
Daisy-chaining the speaker wires from one room to another is not recommended for several reasons, mainly due to the lack of flexibility this configuration affords.
Whether the wires run directly to the speakers or another place in the room depends on the presence or absence of local volume controls; local sources; and, of course, whether the speakers are built-in or freestanding.
Consult with the manufacturer on the proper baffle specifications; One or two two-by-fours between the wall studs might make a big difference in the sound quality. Note that speakers mounted in the ceiling don't provide the best stereo separation.
Be sure to use weatherized speakers anyplace that might have high humidity. Cover the back of the speaker if there will be insulation behind it. Finally, heavy cloth coverings may degrade the speakers' sound.
Local Volume Controls
As equipment gets more capable and less expensive, fewer installations are using local volume controls. If you do, be sure to use the auto-transformer type (as opposed to the L-pad type) to maintain proper impedance match with the amplifier. You should have local volume controls on all speakers that share an amplifier.
If you have a local volume control, the speaker wires will run to this control first, then to the speakers.
You may wish to provide for local audio sources. This allows a television or stereo in the room to use the built-in speakers. One method of providing for local sources is with a manual switch. Another is with an automatic switch that switches the speakers to the local source when present. Refer to the Figure.
In either case you will need some wall-mount jacks to connect to the local source. The speaker wires will go to the volume control first, then to the manual or automatic switch, then to the speakers.
Speaker wire is commonly 16 gauge stranded twisted pair. Larger for very long runs. The twist helps minimize noise pickup. Do not run audio wiring closer than two feet to AC wiring, unless crossing it, cross it at a 90 angle.
Join wires with high quality crimp connectors, never wire nuts. Wall mount speaker jacks should be binding posts or banana jacks.
Audio wiring should be installed after electrical, HVAC, and plumbing is installed. It should be tested immediately after the sheetrock is up, when it's much easier to fix.
Maintain speaker polarity from amp to speaker or the bass response will suffer.
You may want to run line level audio back to the equipment room; For a microphone in a "public" room, for instance. Use 22 gauge shielded twisted pair and RCA connectors.
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