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Loudspeakers: Repairing Decaying Foam Surround

September 22, 2016

The Columbus Speaker Company, a part of Stereo Lab Service, repairs loudspeakers.  The most common problem that many speakers have is a decaying foam surround.  The surround is the membrane that attaches the outer edge of the speaker cone to the speaker basket.  When the cone is unsupported, the cone and voice-coil can make a rattling sound and if this is allowed to continue, the voice-coil will scrape against the magnet structure and result in the short circuiting of coils and or the deformation of the voice-coil.  We can replace these surrounds and restore the speaker to normal operation.

If a voice-coil is damaged by the scraping on the magnet structure or from exceeding the rated power handling of the speaker, the speaker will need to be re-coned.  Re-coning consists of replacing virtually all of the speaker parts except for the speaker basket or frame (which includes the magnet).  The parts replaced when re-coning are: flex leads, voice-coil, spider, cone, surround, gaskets and dust cap.  We are authorized re-cone centers for JBL Professional and JBL Consumer.  We also are factory authorized for Electro-Voice but also can re-cone many other brands using high quality generic parts.

Speakers may also be damaged by over driving or pushing your amplifier beyond its capabilities.  If an amplifier is played too loud, the amplifier will clip the top and bottom of the audio signal being sent to the speaker.  A clipped signal will present a signal to the speaker that is very nearly a direct current, not unlike connecting a battery to a speaker thus turning the voice-coil into a heating coil.  The excessive heat generated by the direct current can burn the coil form, cause the coils to unwind and result in a speaker that is no longer capable of producing good sound or any sound at all.

As you increase the volume setting on your audio system, every noticeable increase in sound level roughly requires that the amplifier double its power output.  The doubling of power output is inconsequential at low listening levels but at higher levels will quickly push your amplifier beyond its ability to deliver a signal that is not clipped as mentioned in the previous paragraph.  Increasing sound levels to this clip point and beyond will not result in a higher sound levels but will result in distortion that may sound louder only because it is unpleasant an obnoxious sounding.

Columbus Speaker Company can repair damage resulting from over driving your system as well as flex lead replacement surround replacement and passive crossover repairs.  The flex lead replacements are needed when the leads are burned or have fatigued because of the repeated flexing.  The flex leads or tinsel leads are the flexible braided wires that carry the electrical power from the terminals on the woofer or midrange basket into the cone and voice-coil.

Stereo Lab Service repairs older equipment such as Electro-Voice, Harmon/Kardon, Infinity,  JBL and more. Stereo Lab Service specializes in repairing older equipment no longer in production. Learn more about us, fill out our service inquiry form or call (614) 268-5500 to get started.