Entertainment Center: TVs, Stereos, VCRs and DVDs - Blown Subwoofer???

Hi,

In my car I have a 10" subwoofer that seems blown because it is fluttering. Does anyone know what would have caused this?? I really do not play my music loud and am suprised that the subwoofer is blown. The box was custom built at a car stereo place in town that is now out of business. This was back in '97.

Thanks,

sweetboy

If you don't crank it up enough to blow it, then just the materials the woofer is made out of tears. It's a very common thing. What kind of speaker is it? What kind of amp powering it?

There is a possibility that whoever built your sub woofer did not use the correct type of cabinet for the speaker you have.

There are speakers that are designed to be in an open type cabinet and acoustic suspension speakers that need to be in a totally sealed box.
Acoustic suspension speakers rely on a cushion of air in the box behind the cone to limit its movement.
If in an open box the cone is free to move beyond its normal range and will be damaged if played at only slightly elevated volume.

I have a prestige car amp. I believe it is 100W per channel and my subbox is one 10" 40 Ohm 100W JBL woofer. I have had this setup for 10 yrs now and things have been playing just fine until a couple of months ago. The Subwoofer is mounted in my trunk and the only thing that has changed since my original installation has been a change to the radio. I went from the dealer radio to an after market radio about 6 months ago.

sweetboy

You should not be complaining if this speaker lasted 10 years without a problem. Over time, the cone weakens and tears like you have found out. Just replace the speaker.

Didn't know that. I thought speakers last forever. So if I replace the woofer, I can expect it to last how long?? 10 yrs??

sweetboy

Depends. If you get a cheap speaker, dont expect it to last forever.

Too many variables to take a guess how long it last. 10 yrs is good for a car speaker.

You can't just toss a speaker du jour into the box. As GregH said, boxes are built for specific speakers. Not just for size, type and style, but also for their electromechanical characteristics. Resonant frequency, bandwidth, and power handling are some of the factors that come into play.

You may be better served in the long run by buying a new subwoofer system. Boxes (especially pressboard, particle board, and MDF) also tend to weaken with age.

"I thought speakers last forever."

I've worked on concert sound systems where the drivers are reconed at least once a year, depending on how severe they've been used. If you buy a good quality properly designed speaker/box system, feed it with the proper amount of power, and don't beat the snot out of it, I can't see why it wouldn't last 10 years. I have a pair of Electro-Voice Sentry 100's I use for the surround mains that I reconed once in 22 years.

As a QA foreman for a speaker manufacturer I can tell you that the speaker cone life can be cut short by ph values sometimes increased to "brighten" the sound as auto stereo designers like to do, the annulus attaching the cone to the housing can tear if overdriven or undamped for acoustic suspension designs. Capacitors can change values with age and temperature (we used polarized electrolytic caps for passive crossover netwoks).To lower a booming resonance we sometimes recoated the cone/annulus. Leaky cabinets were sealed with DAP or Mortite string putty. Quality manufacturing costs more so expect to get what you pay for with speaker system drivers.