way to keep subwoofers from blowing?

Well, that is in an ideal world. Truth is a lot of kids do it themselves or go to say Bestbuy and have them installed. I couldn't even count how many times I have had people show me their systems and turn it up way past the point of distortion. Even at the "authorized dealers" a lot of the time the installs are very poor. A long time ago I went to an autherized Eclipse dealer and had my deck hooked up. I had the rca's labeled sub/front/rear. I even wrote them a diagram on how to wire it up to my system. They had my vechicle from the time they opened to the time they closed. I went out there to see what was taking so long and they were all drinking. Well, they cracked the cover around my stearing column and the worst part is I had one working speaker and not even the antenna was hooked up. (Redmond Automive Saginaw, Michigan.)
Anyways, not everyone is going to an autherized dealer to have their system installed. For some people this is a hobby or some just want to save money. IMO if you had to buy say an Alpine sub with a fuse that had a warrenty on the coil/cone compared to say a Kenwood that had no warrenty which one are you going to buy? I think the only reason that is not implemented is because blown woofers = more money.  I don't know if you have bothered to read any of the warrenties but all of them have an exclusion for burnt coils in subwoofers installed by autherized dealers or not.

jeffchilcott wrote:

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Maybe one of the elders will remember.

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As the tribal dancers undulate to the rythmic beating of the drums, the elders gather to try to remember back to the day...

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

The way to keep subwoofers from blowing?  As a tribal elder (literally, actually) I can tell you kids it's easy: just set them up and use them correctly.  If some idiot whippersnappers want to crank the grain or max out the volume, fine, let 'em blow.  That's what keeps our retail friends in business.  Just don't honor any warranties if your "as-installed" gain and crossover adjustments have been changed.  Fingernail polish on the adjustments works wonders to prove changes...

The new Boston Acoustics G5's have (2) 7.5amp fuses built into the VC, right by the terminals. BA states, like haemphyst, that it doesn't protect against overpowering. These fuses are very convenient for impedance changes, just switch the fuse around!

My two pennies.

I used fingernail polish to mark the settings on all the gains just so I don't screw my OWN stuff up.  Dab a little spot on a point where the screw line meets the surrounding area. A dab on the end of the screw and a corresponding dab where the screw line terminates.

Why don't amps have some way of monitoring and self-adjusting gains? This would nearly eliminate clipping, right? I know that this way it would always be 'wide-open' but it seems someone would have tried by now.

I guess it wouldn't be worth it, though. Cost of parts, new designing, production, no to mention loss of repairs due to proper gain settings...

jmelton86 wrote:

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Why don't amps have some way of monitoring and self-adjusting gains? This would nearly eliminate clipping, right? I know that this way it would always be 'wide-open' but it seems someone would have tried by now.

I guess it wouldn't be worth it, though. Cost of parts, new designing, production, no to mention loss of repairs due to proper gain settings...

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Yes, it would be very expensive to add a circuit like that.  I believe Bang and Olafsun have something similar for their high-end self-powered home stereo speakers.

Well, for starters I disagree that you couldn't stop people from blowing their woofers with a fuse. Lets say a coil can handle 500 watts with no woofer movement using dc current. 500 watts is below the level of power it takes for the speaker to reach the limits of it's excursion. If you set that baby to trip at a low enough level it's not going to fry before it trips. I'm sure some people would try to bypass this to get the max out of their woofer though. You could also use something in amplifiers that once it reached x watts it will shut off. This would not be too expensive to produce. I'm sure we could come up with something simple and cheap using a zener diode and a few other spare parts. This sounds like a fun project. Instead of just coming here saying "oh that wouldn't work" with no proof why not prove me wrong and test it out? First try say a .5 amp fuse on a subwoofer and see if you can blow it. I don't think that is possible, but I could be wrong. Although I seriously doubt that any company would make amps and subwoofer you couldn't destroy it's worth a try to get them to do so. I think people would love the sense of security and it would also give companies more incentive to improve their products.

We apply a sticker over the amp settings, they are virtually impossible to re-apply after removed. It is amazing how many people try to re-stick them after "turning up the power"  .

haemphyst wrote:

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b1kshad0w... are you aware of HOW MUCH CURRENT is actually flowing through a loudspeaker? .5A through a 4 ohm load is only 1 watt! A 1000 watt, 4 ohm woofer would need a 15.8A fuse, to protect it! Over 22A at 2 ohms. I have actually used fuses for protecting loudspeakers, and it WILL work, but I always used a fuse rated about ½ what was necessary, and a "slow-blow" type. This will allow a good margin of error, AND be safe, with transients not blowing it, but long-term overloads taking it out appropriately...

I still maintain that a fuse would never, EVER, protect from over-excursion. You can enter the realm of over-excursion with 5 watts, in an improperly tuned enclosure. Excursion limitations are purely physical limitations, and have nothing whatsoever to do with anything electrical. An accellerometer would be necessary, hard programmed with all of the driver's parameters, with the user inputting total system Q and enclosure type, in a feedback circuit. FAR too expensive to implement for John Q. Public to be interested in such a "solution".

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I was just trying to make a point when I said use a .5 amp fuse. You hae a point about the over excursion in poor or no enclosure. Now you have me wondering how many watts it takes with no enclosure to throw the cone (destroy the surround) without an enclosure compared to with a proper inenclosure. And couldn't you use bump plates to keep the woofer from destroying the surround? I used to have an 18" sub that had a bump plate on it. When it hit that bump plate it made a loud clapping noise. None of my newer subwoofers have had them. Do they still use them?  So what do you think about a fused sub with a bump plate? In a way it seems silly to have to put in safe guards to guard people from themselves, but that's why we make seat belt laws, a microwave automatically stops transmitting when you open the door, there are fences around electrical stations, etc. Imagine what would happen if one day god took out all safety precautions out of everything. Just something to ponder...

Think about the FDA and FTC's hush-hush abilities...

A little off topic.

I'm not old.......

heamphyst wrote:

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people suing McDonalds because they are too stupid to know that the coffee they just ordered was HOT, as it SHOULD be, and they shouldn't dump it into their LAP...

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As a future trial lawyer, it amazes me the number of times I hear this repeated. 

heamph, there is a difference between 'hot' and 'boiling.'  This poor woman was served coffee that was boiling in a styrofoam container.  While she *may* have been partially negligent, a convincing legal argument was made that the temperature of her coffee was the primary reason she dropped it.

McDonalds, in 1986 when this happened, had also had more than 700 previous known incidients of scalding coffee.  They had kept thier coffee more than 20 degrees hotter than any other competetion.

Furthermore, this wasn't some sort of mild pain and a soiled dress.  The coffee was boiling heamph. 

The woman suffered third degree burns all over her legs.

McDonalds was absolutely negligent, in my opinion criminally.  She deserved every penny of her settlement.  Here, the system worked exactly as it was intended. 

https://www.siegfriedandjensen.com/cases.html#sub1

Well, I'd imagine something like this. First tons of people would do things like walk into power stations if you removed the fences. People would be opening their microwaves while the food is still cooking. The hospistals would have lines of people around them for awhile till all the people with no common sense were gone. (Trying to put it as nicely as possible.) I wonder if we would become more intelligent because people would be FORCED to do more thinking and reading of instructions.

Anyone have any more input on my idea of making fool proof subwoofers? Anyone have the time and equipment to try this out? Anyone have any ideas to add?