Ok, this question is kinda vague so bare with me. The other day i was driving down the road and my sub went out. (Kicker Comp VR 15). I've had it for a good year or so. I looked in the trunk to see what was wrong, and i saw that the fuse in my amp was blown. I replaced the fuse thinking that it was the problem, but the sub would still not work. I took the sub inside and hooked it up to the house stereo since my amp kept going into protect mode. I came to realize that the sub was blown as well. (Which really pissed me off). Any suggestions on what happened. I had some stuff sliding around in the trunk, but i dont know what caused it. If the pos and Neg wires touched would that blow the sub and the amp fuse? Im not very familiar with amp fuses blowing, so i dont know what caused it. The amp is a Kenwood 1000 watt mono amp. The fuse was a typical slide in kind (40). I'd appreciate your feedback.
Replies (11)
cplkittle on 02/24/2004 15:29:10
First of all, the sub is a 500w RMS/ 1000w peak sub, and the kenwood amp (one of many that overrate their products) will only push out 480w before blowing the fuse ( volts X amps = watts ~ 12 X 40 = 480).
What might have happened here is that you underpowered the sub, and some clipping occured (square wave) causing the voice coil to get hot and melt the thin insulation. When this happens the speaker for one is toast, but in the process, since the current is not flowing through the entire voice coil (jumping across the short) your impedence drops. An impedence drop will damage the amplifier as well.
This is theory #1. I would try another speaker on the amp as the impedence may not have matched up to your home system, and I don't know what the speaker did when you hooked it up to the home system to let you know that it was blown.
Smell the amp and the speaker and see if you smell any burnt electrical smell.. this is the first indication of a problem ;) I know the smell well.
Black_Rob on 02/24/2004 15:37:09
I hooked the sub up to another amp and the amp just immediately went into protect mode. I figured out it was blown when i hooked it up to my home system cus i could smell the smell. I too am far too familiar with that smell. I think my amp is ok, it just blew the fuse. Im afraid my sub is toast though. I called and a guy said it'd be like 150 bucks to fix. Not worth it. I think the sub-amp combonation was ok, cus i used it for about a year. Like i said, i stupidly had some stuff rollin around in the trunk. Are there any wires that could of touched that would result in the sub blowing and amp fuse blowing. Im just so confused as to why this happened, cus my system always worked well. I did have the sub in a box that was slightly smaller than specs, but like i said, it worked for a year or so. Im still lost with all of this.
cplkittle on 02/24/2004 15:45:34
That is possible. If the hot wire touched a speaker lead, but that is usually 2-4" away from the 12v connection. This would have left a black mark on the terminal from the arc. If your wires are in good shape, a piece of metal would have to touch in both places. not sure in this case though. Most shorts will put the amp into protect mode. Blowing the fuse in the amp is a little less common.
Black_Rob on 02/24/2004 15:49:35
Well maybe this is the question then, What can cause an amp fuse to blown. And do any of these thing correlate to a blown sub?
swez on 02/24/2004 17:35:47
It is likely your sub is shorted... not an open circuit. Can test that therory with an ohmmeter. Each VC should measure about 3.4 ohms if OK. If you get a "0" ohms reading on either VC, that one is shorted.
If you get a very high ohm reading... above 1 Megohm, the VC is burnt open... no connection as wire melted and stopped passing signals to the VC.
Amps usually have a short protect circuit that shuts off the amp when a short or open is detected. In your case, it may have been such a bad short, it took out the fuse too. Rare, but it happens.
To test your amp, get a known good speaker on it and see what happens. If you haved a tiny test speaker or home speaker, turn you gain knob up to 4 volts and keep the HU power minimal. What do you get with this?
As Kittle said, your amp is not a true 500 watts RMS, depending on how much voltage it gets from the electricals of your car. However, if you had the gain on the amp set wrong or too much bass boost, the amp will start clipping badly. (even is gain is correct and little boost is used)
Clipping can send high amounts of non-audio voltage to the sub, but since it is clipped, the signal looks more like a square wave or DC. This will kill any sub in time. Subs cannot handle DC or square waves well as the cone will not move (motivate) in and out enough to cool the VC's. That will fry the VC's to short or open.
Swez
Black_Rob on 02/24/2004 19:08:47
Ok fellas thanks. Do shorted, burnt open, and whatever else was mentioned mean that my sub is done for? Each case makes it sound like it, but i want to make sure before buying new subs. Do you have any clue what my gain should have been set on to prevent this clipping? Im not an expert on this stuff as you can tell, so im tryin to figure it all out. Thanks alot guys.
swez on 02/25/2004 03:56:10
Sub is toast... time to replace.
About amp gains... set these to match the HU output levels speced in the HU manual. Most newer HU's can do 4.0 volts. Older units have ~2.0 volts. Your amp gains should match that voltage.
I have FAQ's on tweaking subs and clipping issue in the featured articles in our DIY section.
http://www.clubknowledge.com/Car_Audio_FAQ/?t20
http://www.clubknowledge.com/Car_Audio_FAQ/?t3
Hope that helps and HAPPY reading!
Swez
Black_Rob on 02/25/2004 18:30:50
When i hook up the sub that appears to be blown, It sends every amp i hook up to it into protect mode. Will that tell you anything?
swez on 02/25/2004 19:32:22
Yes, voice coil shorted... amps will go into protect mode immediately.
This is often caused by high distortion voltage spikes from a smaller sub amp. The amp will try to put out as much signal as it can, but there comes a point when the amp reaches its limits and gets very dirty. (high distortion values)
Swez
Black_Rob on 02/26/2004 23:22:09
So since the voice coil is shorted, does that mean that my Sub is toast. And how much would it cost to be fixed, if it could be fixed? Thanks again Swez, youre a genius.
swez on 02/27/2004 12:35:20
That sub is taost!!! Not worth fixing... most recones run $75.00 or more. If you had a $400.00 sub, yes it would be a good recone candidate... not anything more than 30% of the cost new is worth reconing unless you have a matched pair and want to keep that sub regardless of costs.
Not a genius... just an old fart that has been at this a while. Thanks for the kuddos though!
Swez
Replies (11)
cplkittle on 02/24/2004 15:29:10
First of all, the sub is a 500w RMS/ 1000w peak sub, and the kenwood amp (one of many that overrate their products) will only push out 480w before blowing the fuse ( volts X amps = watts ~ 12 X 40 = 480).
What might have happened here is that you underpowered the sub, and some clipping occured (square wave) causing the voice coil to get hot and melt the thin insulation. When this happens the speaker for one is toast, but in the process, since the current is not flowing through the entire voice coil (jumping across the short) your impedence drops. An impedence drop will damage the amplifier as well.
This is theory #1. I would try another speaker on the amp as the impedence may not have matched up to your home system, and I don't know what the speaker did when you hooked it up to the home system to let you know that it was blown.
Smell the amp and the speaker and see if you smell any burnt electrical smell.. this is the first indication of a problem ;) I know the smell well.
Black_Rob on 02/24/2004 15:37:09
I hooked the sub up to another amp and the amp just immediately went into protect mode. I figured out it was blown when i hooked it up to my home system cus i could smell the smell. I too am far too familiar with that smell. I think my amp is ok, it just blew the fuse. Im afraid my sub is toast though. I called and a guy said it'd be like 150 bucks to fix. Not worth it. I think the sub-amp combonation was ok, cus i used it for about a year. Like i said, i stupidly had some stuff rollin around in the trunk. Are there any wires that could of touched that would result in the sub blowing and amp fuse blowing. Im just so confused as to why this happened, cus my system always worked well. I did have the sub in a box that was slightly smaller than specs, but like i said, it worked for a year or so. Im still lost with all of this.
cplkittle on 02/24/2004 15:45:34
That is possible. If the hot wire touched a speaker lead, but that is usually 2-4" away from the 12v connection. This would have left a black mark on the terminal from the arc. If your wires are in good shape, a piece of metal would have to touch in both places. not sure in this case though. Most shorts will put the amp into protect mode. Blowing the fuse in the amp is a little less common.
Black_Rob on 02/24/2004 15:49:35
Well maybe this is the question then, What can cause an amp fuse to blown. And do any of these thing correlate to a blown sub?
swez on 02/24/2004 17:35:47
It is likely your sub is shorted... not an open circuit. Can test that therory with an ohmmeter. Each VC should measure about 3.4 ohms if OK. If you get a "0" ohms reading on either VC, that one is shorted.
If you get a very high ohm reading... above 1 Megohm, the VC is burnt open... no connection as wire melted and stopped passing signals to the VC.
Amps usually have a short protect circuit that shuts off the amp when a short or open is detected. In your case, it may have been such a bad short, it took out the fuse too. Rare, but it happens.
To test your amp, get a known good speaker on it and see what happens. If you haved a tiny test speaker or home speaker, turn you gain knob up to 4 volts and keep the HU power minimal. What do you get with this?
As Kittle said, your amp is not a true 500 watts RMS, depending on how much voltage it gets from the electricals of your car. However, if you had the gain on the amp set wrong or too much bass boost, the amp will start clipping badly. (even is gain is correct and little boost is used)
Clipping can send high amounts of non-audio voltage to the sub, but since it is clipped, the signal looks more like a square wave or DC. This will kill any sub in time. Subs cannot handle DC or square waves well as the cone will not move (motivate) in and out enough to cool the VC's. That will fry the VC's to short or open.
Swez
Black_Rob on 02/24/2004 19:08:47
Ok fellas thanks. Do shorted, burnt open, and whatever else was mentioned mean that my sub is done for? Each case makes it sound like it, but i want to make sure before buying new subs. Do you have any clue what my gain should have been set on to prevent this clipping? Im not an expert on this stuff as you can tell, so im tryin to figure it all out. Thanks alot guys.
swez on 02/25/2004 03:56:10
Sub is toast... time to replace.
About amp gains... set these to match the HU output levels speced in the HU manual. Most newer HU's can do 4.0 volts. Older units have ~2.0 volts. Your amp gains should match that voltage.
I have FAQ's on tweaking subs and clipping issue in the featured articles in our DIY section.
http://www.clubknowledge.com/Car_Audio_FAQ/?t20
http://www.clubknowledge.com/Car_Audio_FAQ/?t3
Hope that helps and HAPPY reading!
Swez
Black_Rob on 02/25/2004 18:30:50
When i hook up the sub that appears to be blown, It sends every amp i hook up to it into protect mode. Will that tell you anything?
swez on 02/25/2004 19:32:22
Yes, voice coil shorted... amps will go into protect mode immediately.
This is often caused by high distortion voltage spikes from a smaller sub amp. The amp will try to put out as much signal as it can, but there comes a point when the amp reaches its limits and gets very dirty. (high distortion values)
Swez
Black_Rob on 02/26/2004 23:22:09
So since the voice coil is shorted, does that mean that my Sub is toast. And how much would it cost to be fixed, if it could be fixed? Thanks again Swez, youre a genius.
swez on 02/27/2004 12:35:20
That sub is taost!!! Not worth fixing... most recones run $75.00 or more. If you had a $400.00 sub, yes it would be a good recone candidate... not anything more than 30% of the cost new is worth reconing unless you have a matched pair and want to keep that sub regardless of costs.
Not a genius... just an old fart that has been at this a while. Thanks for the kuddos though!
Swez
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