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How Not to Wax Your Speakers

Though many 12-volt fans might fantasize about it, you wouldn’t like living in your car: It’s a rough environment. Cars are full of vibration, countless road-surface impacts and temperature swings roughly equivalent to Mars. Unfortunately, even though autosound speakers are designed with this harsh climate in mind, many suffer shorter life spans than those disappearing Martian landers. Rarely, however, are the elements to blame for “blown” speakers.

Unlike a set of home speakers, in which the engineering is packaged in its own box, a car system contains many variables, including the enclosure, cross-overs, and power source. These elements are your responsibility, so avoiding major missteps in design and use can wildly extend the life of your car speakers.

The three most common killers of speakers are excessive power, way-ward frequencies and an overstressed power supply.

Much like your car itself, car speakers tend to perform best when properly driven. The likeliest culprit in "speaker-cide" is too much power. Overdriving a speaker means sending it more signal than it can physically produce. If force-fed via a ham-fisted volume control, any speaker will give its life trying to produce sound levels beyond its capabilities.

Simply because of the size of its components-which are less able to dissipate heat and offer less “suspension” to handle sudden power peaks-tweeters are usually the first to go. Also, unlike other drivers (which might produce a rapping or slapping sound if overdriven), tweeters may not give an audible sign of distress before checking out. “Edgy” and “harsh” are usually their last reported descriptions, and then they blip off the radar.

Overdriven is not to be confused with “loud.” A properly installed audio system can render you near deaf without harming the drivers at all. “Properly installed” means amplifier levels are calibrated so speakers are not overdriven at normal volume settings, and each driver in a component setup (via the crossovers) only receives its appropriate frequencies.

Though it applies to all speakers, tweeters are also normally the first casualty in a system where frequencies are misrouted (1-inch dome tweeters were never intended to handle 50Hz drum kicks). Sub-woofers can easily suffer the same fate at the other end of the audio spectrum. Pumping up the bass (especially with an equalizer), in search of frequencies outside the realm of your sub’s driver/ enclosure/amp will have the woofer’s cone flopping back and forth worse than a cornered politician.

The search for subsonic bliss can also shorten your speakers’ life span. Looking for bass beyond your woofer’s setup design can put exponential loads on an amplifier, causing it to choke, or “clip,” sending potentially harmful signals to your speakers. Amplifiers also tend to clip during periods of high demand due to an inadequate power supply (which includes everything from the car’s alternator to your amp’s internal power source).

If your car is not properly wired, when asked for some serious grunt, entire system voltage can drop, greatly lowering an amplifier’s output capability. An amp starved for voltage can give up the ghost early, clip and take speakers down with it.

To avoid all these pitfalls, proper setup is key. If you are popping speakers like aspirin, common solutions are a lower amplifier level (so that normal volume settings are not lethal), a re-tuned crossover frequency (giving the speaker a narrower range of sound to reproduce), or a steeper crossover slope (which rolls off more difficult frequencies more rapidly). Properly tuning your subs’ crossovers and enclosures to provide sufficient bass for your musical tastes can also mean far less stress on your amps, extending the life of all your drivers. Find the balance between levels, crossovers and a stable power supply, and your speakers will live as long and loud as you like.

This article was last modified Jul 28, 2014

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