How to Troubleshoot a Woofer
Troubleshooting a woofer loudspeaker is done using visual inspection methods and, if necessary, performing some simple mechanical and electrical tests.
If the woofer is producing poor quality sound, including annoying crackles or pops, test results will reveal whether the cause of the distortion is as basic as loose or shorted signal wires, or extends to damaged voice coil, magnet and spider assembly or cone material.
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Things You'll Need
- Flashlight
- Magnifying glass
- Screwdrivers
- 1-1/2 volt, AA battery
- Small diameter, insulated copper hookup wire
- Wire strippers
- Electricians tape
Instructions
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Woofer Grille Removal
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Removal of woofer grille assembly Remove the speaker grille assembly from the front of the speaker enclosure.
These are usually mounted using a plastic or metal, snap-off-ball and socket device at each corner of the speaker enclosure.
Apply gentle pressure at each corner to separate the grille assembly from the enclosure. Set the grille assembly aside for later re-installation.
On professional equipment, some woofer grilles are mounted with retaining screws which can be removed for visual inspection of the woofer cone material.
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Torn woofer cone material Visual Inspection Test
Visually inspect all surfaces of the woofer cone for damage. Note any torn or ripped speaker cone material, including around the edges of the speaker, the suspension area, and across the surface.
To reveal tiny tears or cracks, use the magnifying glass with a flash light directed toward the surface of the woofer cone. Try aiming the flashlight on an angle so smaller tears are easily visible.
Tears in the surface of a woofer cone can be repaired with a re-coning kit. (See Step 5 and References)
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Reconing a damaged woofer Woofer Cone Excursion Test
Gently apply fingers of one hand, evenly spaced around the woofer cone assembly and gently press the cone rearward, no more than 1/8 to 1/4 inch, and allow it to return to it's center. Observe if the woofer cone moves freely, or if it seems to 'drag' when pressed rearward. This dragging response would indicate a damaged voice-coil assembly, requiring removal and replacement by a qualified speaker technician.
Replacement of the woofer may be less expensive than replacing a damaged voice coil assembly.
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Typical hookup wire used for electrical test of woofer Voice Coil And Connecting Terminals Electrical Test
Access the rear of the woofer by removing the woofer from its enclosure using a screwdriver, or removing the back panel from the woofer enclosure using a screwdriver. Use caution when handling the woofer to avoid damaging the cone area.
Note the two-each, speaker wire connecting terminals on the rear of the woofer frame, adjacent to the magnet assembly. Check if the connected signal wires are solidly attached to each terminal by solder, or a spade-lug attachment method. Check the solder quality appearance, and re-solder as needed. (see Step 6)
Using the wire stripper, remove 1 inch of insulation from each end of 2 12-inch long wires.
Temporarily attach one end of each wire to the 1-1/2-volt AA battery using a short piece of electricians tape, one wire on the positive end, and one wire on the negative end.
While holding the battery and wires near the woofer terminals, hold one wire to one woofer terminal and briefly touch and remove the other wire to the other speaker terminal, and listen for a gentle 'pop'.
This test confirms that the woofer terminals are electrically connected to the voice coil assembly inside the woofer.
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The reconing kit includes parts and instructions for cone removal and installation Repairing a Woofer Using A Re-coning Kit
Locate the appropriate re-coning kit for your woofer online. (See Resources)
Re-coning kit prices on October 11, 2010 were in the $25.00 to $100.00+ range depending on the woofer's manufacturer, cone diameter, and cone material.
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Solder A Loose Connecting Wire
Using a low-wattage soldering iron, heat the terminal briefly and reattach the connecting wire, adding a small amount of rosin-core solder as necessary and allow to cool.
Do not overheat the terminal, but remove the soldering iron's tip as solder begins to flow.
Test the woofer to see if the issue has been resolved.
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Tips & Warnings
Use caution when handling the woofer. Avoid contact with any sharp object that would damage the cone area.
If soldering, use rosin-core solder on electrical connections.
Use eye protection when soldering, as splattering solder and rosin can damage the eyes.
References
Resources
- Photo Credit Pliers and wire cutters image by Albert Lozano from Fotolia.com Loudspeaker image by robootb from Fotolia.com speaker image by CraterValley Photo from Fotolia.com Speaker mounted on wooden box image by Sudheer Sakthan from Fotolia.com speaker wire image by Paolo from Fotolia.com A Grey Loud Speaker. image by daseaford from Fotolia.com
