my first magic smoke show, need an audio junkie

hey guys, got my first ever smoke show this week, but not from my subs. the crossovers to my dls comp set melted and smoked a little

not at the same time tho about 2 days apart, and they took both mids with them leaving me with only tweeters i tried switching out the crossovers with some boston acoustics, and still, could only get the tweeters to play, well this sucks.

took one mid out and tried touching the leads to a cordless drill battery and nothing, not even a buzz.

now im kind of doubting having them both go out in the same week is coincidence, and someone told me to get my amp checked to see if dc voltage is leaking through, I have a dmm, but not completley sure what im doing.

is this common for an amp to pass dc? its a cheap orion cobalt 600.2 giving i think 75 rms per side.

everythings been fine for almost a year...

 

I could probably help you out if i knew what the hell you were trying to say.

 

how can i find out what happened to them, and how to properly test for dc voltage, googles coming up short on this one...

 

His crossovers suddenly started smoking/melting and in turn destroyed his mids, leaving only tweeters. I got it..

Electrical components catch fire because of too much current given to a component that can't handle it. Electricity is energy, and energy is heat. So if the energy supplied is not used efficiently by the component, it turns to heat, and melts. Physics.

Now, what caused the excess power is the question. Bad amp would not "leak DC voltage"... if you measure your speaker leads with the dmm while playing music, your dmm will read +DC voltage. So it won't "leak" power. However, if something in the amp goes horribly wrong, and the power is no longer regulated, then a mass fluctuation in current will result. Only 3 possible things could have caused this:

1- defective crossovers (which now doesn't matter anyways since they are toast)

2- short circuit (either in the amp or in the crossover. Both units frying separately leads me to believe its not the crossover though, so either BOTH of your speakers were wired incorrectly and probably touching ground on the positive side of the voice coil, or option 3...)

3- your amp is toast. This is the most probable answer.

Solution- Replace amp, crossovers, mids (and probably hi's also), and any speaker wire between amp/xover/speaker and hope for the best!

 

anyway to tell if the amp really is toast? still powers up fine and plays the tweeters...im doubting the wires are bad, or cut anywhere, i ran them under the carpet and the jacket is really thick.

think ill pick up a set of cheap co-ax's and see if they burn up.

 

^^^ there ya go. Sounds like pro force nailed it. Your amp probably just took one hell of a shit on you.

I don't really see how it could be anything seeing as you only had problems all of a sudden.

Have you looked over all of your wiring thoroughly?

 

Not without special equipment. You cant really test an amp effectively with just a dmm. I'm pretty sure its toast. I'd advise against the cheap paper coax idea. If it happened once, it will happen again, and this time you might not be lucky enough to catch it before your truck goes kaboom and under the carpet is exactly the reason the wires need to be checked. If the source of the problem is the amp, and the crossovers burned, then everything I'm between (wire) is compromised. If part of the shield partially melted and is grounded to your floor, that may have been the reason your amp fried. It could also cause a slow arc and ignite the carpet. NEVER EVER EVER assume the wire is fine!! If your feet start smoking while driving, don't say I didn't warn you!

 

Amen

 

Hard to work on this when my work schedule makes me do 120 hours before I get a day off guess I have an excuse to upgrade. But if a power wire was grounded wouldn't that either blow a fuse or put my amp into protect?

 

Ideally that is how it is supposed to work, but nothing is perfect. In have seen tons of electrical fires caused by system failure like this. Its usually to smallest problems that cause the worst failures. If a wire is simply cut in half and clearly shorts out then yes your fuse should pop no problem. But a slight hairline fray in the shielding caused by the wire rubbing against something could result an a small short which creates an arc. This short is not enough to trip the fuse or cause the amp to protect itself, but it is enough to cause massive heat to result and things melt quickly. Also if your fuse is too large or is cheap it may not pop when it should.

Perfect example, just 2 weeks ago I was adding a smartstart module to my alarm. I was working under the dash by the fuse box and steering column. Keep in mind I am a very experienced installer and I do top notch work, but even the best installs have accidents. So anyways, I took the lower dash off and while I was digging around in there I felt something burn my arm... I look around and. Notices 3 fuse holders all melting and wires smoking. All 3 wires had 1 thing in common.. they were all connected to the ignition wire. Fuses did not pop, but they melted like I've never seen before, and I've seen some pretty bad things melt before so after searching and searching for what was causing the failure, I found that one of the taps connected to the ignition which supplied power to all these aftermarket wires, a single copper strand (very very very tiny) in the wire had bent back and was sticking out of the connector. I had not noticed it before until I started digging around in there. Apparently that wire got moved very close to the metal shroud under the steering column and was barely touching metal. Its the worst type of short circuit ever. I could have destroyed the entire truck in minutes. And I mean literally totalled the truck from electrical damage because of one single copper strand that was loose.

Moral of the story, electrical problems are no joke. If you had something get so hot that it melted, that means you have a serious serious problem. Worst part is that also means its going to be so small its going to be a difficult problem to pinpoint. My guess is still the amp, but if the wire under your truck was heated up beyond its heat rating and has the slightest signs of heat damage, it needs to be replaced. Because it may seem fine now, but a month from now you might be in it for the worst.

Also keep in mind that speaker wire may appear to have way thicker rubber jacket and shielding than most other wires in the car, BUT, it also has a way lower heat rating then standard primary wire. The thickness is to protect against electrical "noise" to keep the signal lines clean and remove distortion from your system. Power lines radiate interference that speaker wires need to be shielded from. This is why they look beefy. But surprisingly, the heat rating is super low because speaker wire is not intended to carry large amounts of current (which is what happened to you). Those tiny little primary wires in your truck and what you should use on just about everything except your speakers is way safer for current handling and heat protection. Just food for thought. Hope this helps you better understand how electrical works.

EDIT: just to clarify, it doesn't have to be a "power" wire that was grounded... it could have been a frayed speaker wire as well which causes the same failure.

 

so if this is the case why didnt my tweeters get taken out as well? both crossovers melted in the same specific spot, right around one of the "white box things" buddy told me is a resistor....if that helps.its an entire day taking things apart and checking, just dont have the time.

 

Yes that would be a resistor. A resistor does just that... it resists the flow of current. Imagine a fire hose connected to a fire hydrant, then at the open end you connect the fire hose to a regular garden hose, then turn on the water.... the amount of water flowing will be restricted once it hits the garden hose and this will result in a lot of pressure inside the hose. If you continue to turn the water higher and higher, eventually the garden hose will burst because it can't handle the pressure.

Like I have mentioned before, electricity is energy, and energy turns to heat. So any resistor naturally gets hot anyways because its purpose it to reduce the amount of current. It does this by burning the energy, which results in heat.

Now apply these 2 things together and the result is: too much current supplied to a resistor that is not rated to handle that much current, will result in the resistor doing its best to stop the excess flow by burning energy, which in turn results in lots and lots of heat, and eventually failure. Failure of the resistor causes all that extra current to now flow freely to your speaker, which instantly fries. Ypu don't even get a "pop" with the drill battery because the voice coil is so destroyed from the overload.

Now, to understand why the tweeters did not fry.... the smaller the speaker, the less power it can handle, therefore the larger resistor needs to be used. The resistor that fried is probably for your kids. It is a lower value resistor and therefore fails easier. The tweeter is so small that their resistors are very large and can handle way more power before failing. If they were left on after the first failure, then my guess is eventually the tweeters would fail too after prolonged exposure to the increased current flow.

That increased current was cause by 1 of 2 things. Either your amp failed inside, or your speaker wire shorted out. Or both. One may have caused the other or vise versa. You don't have to disassemble the entire system. Only the speaker wire the runs from amp to crossovers. I would say that takes no more than 15 minutes tops on each side to pull the old wire and install a new one. Or just 5-10 minutes of all your doing is "checking" the wire and not replacing it. Shouldn't take a while day.

IMO 30 minutes of my time for the comfort and security of knowing I don't have a potential electrical fire just waiting to start is a pretty good investment of time. Its 30 minutes to make sure your truck isn't going to randomly light up in flames in the middle of cruising down the freeway. You said the wires were under the carpet... if they are under your driver seat area, imagine the wire heats up, starts a small fire under your seat. Within seconds the heat melts your seat belt buckle, making it impossible to remove. Then the seat goes up in flames, you crash, trucks on fire, and nobody can get you out now.

More realistic version of my horror story: even if the wires aren't under the seat, let's just say the are under your feet area. Carpet catches fire, you go oh shit and try to stomp out the fire while doing 70mph down the highway, start swerving and crash. Airbag deploys, you hit your head and go unconscious upon impact. Now the truck is engulfed and your trapped inside.

I'm not making up some Final Destination stories here just to exaggerate . These are very real life scenarios that have happened before. Google vehicle electrical fire stories, I'm not just blowing steam here. I'm not saying this is guaranteed to happen, and chances are it won't. But I'm just saying 30 minutes is a small investment to protect your life as well as your truck. If you get an electrical fire, your truck will be totaled. Just trying to stress the importance of this. Components burning up is a very very serious problem. If it takes a whole day for you, then wait till you have time, or take it to a shop and get a rental car for a day. Its that important.

Good luck!

 

Canada. Sorry to butt in here. Been watching this site for a few years but this is actually my 1st post. I have a simple question. Have you considered the possibility that you have just over-driven your system for too long? There are a few scenarios that could be related to that. For one, if the crossover frequency from your mid to sub is improperly tuned you may be in effect trying to deliver too much power to the mid bass range. In terms of current, your speaker will try to handle any amount of power you give it until it reaches it's breaking point. Low frequencies require much more power than high frequencies to produce the same perceived output level. If improperly tuned your mid speakers may be trying to act as subs and as a result are attempting to draw excessive power. Hence, they probably just burned up. That would be one explanation as to why your tweeters are fine. They were still using power that was within their design parameters at the frequency bandwidth they operate at.

Keep in mind that if your resistors in the crossovers actually burned and failed it's because something downstream of them was simply trying to draw too much current. A shorted speaker is a prime candidate.

I have personally had a situation where a high current sub harmonic frequency from a failed Yamaha power amp completely toasted a pair very expensive speakers in a record studio but the likelihood of that happening is very low.

Secondly, you may have just identified the design limits (or flaws) in the cross-over units themselves, although I doubt that is the case. The fastest and easiest first step you can do is to remove the speaker wires from one of your mids and just use your ohmmeter to check the coil for either a dead short (most likely) or for a complete open circuit. All coils have an inherent DC resistance so if its good you will read some value on your ohmmeter. If you do find the speaker to be bad then test the other mid and you should get the same result. If that is the culprit you most likely will need to replace only the mids and crossover units. Just an opinion. Good luck.

 

From one experienced installer to another (former installer), that right there is why I would rather solder every connection (granted, the same problem could happen from soldering).

Using taps, more often than not, especialy incorrectly sized taps, leads to frayed wires. I have had my share of having to use them as well, though I never liked it.

Anyhow, you get +1 from me for presenting your (professional?) opinion in a clear, informative, and logical manner.

 

Proforce rules...hes helped me big time

 

Yeah i was MECP for several years and have always enjoyed installing. Its just a side gig now but i still love it. Sometimes its a PITA to solder and shrink tube
every connection depending where they are located, so connectors are the only option. Or I just got lazy lol. Thanks for rep though, I help whenever I can.

Thanks! :thumbup:

 

Everything ProForce has said is 100% accurate.. Guy knows his shit and take his advice as I can't add anymore than Profroce already did.

 

I'm not gonna lie, the gain on the amp was near 100% set on hpf, I'd guess around 85% on the gain, did the old, turn deck to 75% volume and turn gain till you hear distortion, I tune everything by ear, not the best method for sure, but this is the first time I've blown a speaker or a sub in like 10 years.

Checking wire involves taking the seat and hu out so it'll take a little longer than 30 mins. Not to mention getting thick gauge speaker wire through the door boot was almost the hardest thing I've ever done lol if the speaker wire looks good I'll take my amp in to get tested at an electronics repair place.

Anyone have a set of 6.5 components for sale?

 

Well after messing with it some more, seems my shitty Orion cobalt is the culprit, checked what wiring I could get to easily and it all looked fine.

Sealed up my doors a little better and got a set of hertz esk 165s for 200 tax in. Locally, and an eclipse ea2000 for 105 from a pawn shop. But I kept the dls tweeters instead. Sounds very clear, punchy, and crisp, but I still have tweaking to do. Thanks for all the help.