Smoked my tower amp

[prostar205]

Well, after 15 year the tower amp (Kicker KX850.4) gave up the ghost. Here are some pictures. Fired 2 of 3 40A fuses and melted a 4AWG ground wire in the terminal. Interesting that did not not blow the 125A fuse protecting the power lead.

Anyone have ideas on how this happened?

I will be replacing it with either a Kicker KXMA800.4, Rockford T600-4 or Wetsounds SNY-DX4.

Before replacing it, I'd like to know if there is anything in my wiring setup that could have contributed to this. I don't think so since I really haven't touched the wiring since I installed in in 2007.

Any help would be much apprecaited.

[dpb185]

I think 125A it too large of of a fuse to protect a 4 AWG wire. Here is a reference:

https://www.bluesea.com/resources/1437

I used a 100A fuse in mine. Someone who is an expert at this could tell if 125A vs 100A is a big enough difference to matter.

How long is the wire that melted ? I would think less than 6 feet ?

[waterlogged882]

Best smoked amp I have seen.

I also see bare copper wire. Strip the sheathing on the 4AWG wire and see if it shows signs of corrosion anywhere throughout the length. However I don't think that is the primary cause.

From the manual, the specs on the amp specify 120A rating, but I am not sure if that is a number I don't understand.

Next new wire(s), use tinned copper.

Nice shoes.

US $.02

.

[bturner2]

First off, glad you're OK and the boat other than this temporary set back is good too.

I'm sure MLA will jump on this but these would be my observations.....

• 125A is nuts IMO. Not sure where that recommendation came from but I think it's crazy and as we see here useless for protection. A JL Audio 600/6 (that's ~600 watts) for example recommends a 60A breaker, that's less than half what you were running. At 125A you're basically running a piece of speaker wire for a fuse. Unless this is for a primary run to feed multiple amps it is again IMO way too big and will produce the results you got.
• To get the results I'm seeing you had to experience a dead short in the amp but even then the 40A fuse on the amp should have blown before it melted down. Not sure how it could get this bad without a dead short and all of the 125A's getting to the feed. That basically looks like a straight short across a battery type of damage.
• Depending on the panel layout and where its located, I like to have my breakers (I don't use fuses) within 6" of the battery (the closer the better). This set up means the circuit is protected within 6" of the batter going out to the device. If I have to wire to a remote panel located in another part of the boat I use that same rule from the panel. I also will run a breaker even if that amp is fused like this one, for this reason. The breaker and wired size are dictated by the manufacture's recommendations keeping in mind that the length of the circuit run will also affect the breaker size.

As to what happened.....

• Did the amp get wet by any chance?
• Were you cranking it to max at the time?
• Are there any non marine rated components used in the wiring?
• Did a competent shop do the work (the answer here IMO would be no)?

You're lucky this was the only thing that got damaged. A few gas fumes or some flammable materials by where the damage occurred and the boat goes up. If this were my boat I would pull all the stereo wiring and start from scratch. Draw out your wiring plan and post it here. MLA helps with these types of questions all the time and is a wealth of good information and free advice.

While you're at it I would go through the rest of the electrical system and look for damage in the other circuits as well. Get rid of anything that isn't marine rated like the non-tinned wire in the picture for the amp feed. But that's me, I'm sure others will have different opinions.

[waterlogged882]

First off, glad you're OK and the boat other than this temporary set back is good too.

I'm sure MLA will jump on this but these would be my observations.....

• 125A is nuts IMO. Not sure where that recommendation came from but I think it's crazy and as we see here useless for protection. A JL Audio 600/6 (that's ~600 watts) for example recommends a 60A breaker, that's less than half what you were running. At 125A you're basically running a piece of speaker wire for a fuse. Unless this is for a primary run to feed multiple amps it is again IMO way too big and will produce the results you got.
• To get the results I'm seeing you had to experience a dead short in the amp but even then the 40A fuse on the amp should have blown before it melted down. Not sure how it could get this bad without a dead short and all of the 125A's getting to the feed. That basically looks like a straight short across a battery type of damage.
• Depending on the panel layout and where its located, I like to have my breakers (I don't use fuses) within 6" of the battery (the closer the better). This set up means the circuit is protected within 6" of the batter going out to the device. If I have to wire to a remote panel located in another part of the boat I use that same rule from the panel. I also will run a breaker even if that amp is fused like this one, for this reason. The breaker and wired size are dictated by the manufacture's recommendations keeping in mind that the length of the circuit run will also affect the breaker size.

As to what happened.....

• Did the amp get wet by any chance?
• Were you cranking it to max at the time?
• Are there any non marine rated components used in the wiring?
• Did a competent shop do the work (the answer here IMO would be no)?

You're lucky this was the only thing that got damaged. A few gas fumes or some flammable materials by where the damage occurred and the boat goes up. If this were my boat I would pull all the stereo wiring and start from scratch. Draw out your wiring plan and post it here. MLA helps with these types of questions all the time and is a wealth of good information and free advice.

While you're at it I would go through the rest of the electrical system and look for damage in the other circuits as well. Get rid of anything that isn't marine rated like the non-tinned wire in the picture for the amp feed. But that's me, I'm sure others will have different opinions.

Good information and assessment. I always learn from your posts as well as MLA.....several of the few SMEs here on audio (of which I am not). Thanks.

.

[prostar205]

I think 125A it too large of of a fuse to protect a 4 AWG wire. Here is a reference:

https://www.bluesea.com/resources/1437

I used a 100A fuse in mine. Someone who is an expert at this could tell if 125A vs 100A is a big enough difference to matter.

How long is the wire that melted ? I would think less than 6 feet ?

The ground wire that melted is only about 12 inches long. It comes off a distribution box.

[prostar205]

Best smoked amp I have seen.

Nice shoes.

US $.02

.

No shoes allowed in the boat....

[prostar205]

First off, glad you're OK and the boat other than this temporary set back is good too.[/LIST]As to what happened.....

• Did the amp get wet by any chance?
• Were you cranking it to max at the time?
• Are there any non marine rated components used in the wiring?
• Did a competent shop do the work (the answer here IMO would be no)?

The amp did not get wet. It's under the observers area. I have been running this setup for 15 years with no issues. I do think (and hope), it was just an internal short in the amp and not an issue with the boat wiring. However, those 40A fuses should have blown.

Yes, this happened when the tower speakers were being driven fairly hard. In the past, the amp would overheat (even though it has an internal fan). We would just open the seat back in the observers seat area and let is cool down for a few minutes. Then it would go back on.

Wiring - Yes, all of the power wires are not marine grade. They are car stereo grade. I have 0 AWG going from the 2 batteries back by the engine to distribution blocks under the observer's area and 4 AWG going to each of my amps (Kicker KX600.1 - Sub, Kicker KX650-.4 - boat speakers, Kicker KX850.4 - towers (RIP)).

I did all of the install back in 2007

[prostar205]

Here are some pictures of the distribution blocks and the main stereo fuse back by the battery. This pictures are very good but hopefully it shows what I'm working with. As included is a hand drawing wiring diagram of the stereo and how its hooked up.

As you can see from one of the pictures, the large "smoked" amp was located under the other amp on the wall.

Any and all comments are welcome.

[dpb185]

So I found this on the World Wide Web of all things:



Were you using 4 gauge or 2 gauge wire ? The 120 amp fuse makes sense for 2 gauge but might be oversized to protect a 4 gauge wire.

[prostar205]

All the amps are fed from the distribution block with 4AWG wire, albeit not marine grade. Looks like the KX-850.4 amp should have been 2 AWG with a slightly lower fuse rating (120A vs. 125A).

[dpb185]

My guess would be you had some degradation in that wire that burned up. Either corrosive or thermal. Then when running high output you put enough load on it to melt it. The degradation meant that instead of it being able to handle say, 150 amps, it could only handle something less, like 100 amps. Obviously less than 120 amps or your fuse would have blown.

[dpb185]

I'm kind of wondering if I'm over-fused / under-protected on my amp. I have a Wetsounds DX-4 amp. 4 gauge wire with 100 amp ANL Fuse. Any thoughts from the experts ? It looks like I could go down to an 80 amp fuse pretty easily.

[bturner2]

The installation sure looks clean enough and the doc is stating a 125A fuse but the results don't lie. Something sure as heck didn't trip when it was supposed to. Is the 125A fuse located at the battery/distribution block or at the amp/amp rack/board? If at the amp, IMO that needs to go to the distribution panel or source of power. I'll be honest here and say that I've never done multiple 1000 watt amps. The systems I've done have all consisted of 2 or 3 amps in the 200 to 600 watt range. On those I've run sperate primary runs for the power directly to the battery or distribution panel then protected them with breakers individually. The higher powered amp rack solutions I've seen pretty much did the same only they still protected the source at the panel or battery then on the individual runs going to the amps with breakers at the amp rack as well. The idea being that each individual amp is protected as well as the source run to the battery.

IDK, I'd really like to hear what MLA thinks about this or where he might suggest the issue came from. IMO you should never, ever see this type of event. I pulled down the specs and installation instructions to see where something may have gone sideways. These BTW are for the marine version.



If there is a silver lining here and you have a bunch of cash you're looking to burn this would be a great opportunity to go to much smaller and efficient amps.

[prostar205]

bturner2 - both distribution blocks (ground and power) are located under the observers area next to the amps. I do have a 250A fuse located back by the batteries that "protects" the entire system.

Since my system is 15 years old, I am now thinking of replacing all three amps to smaller, more efficient components.

I too am interested in what others thoughts are, including MLA. I am going to tear into the smoked amp this afternoon. I'm hoping to find some components (resistors, diodes, etc...) that are toast that may have led to the amp cooking. If not, I work in aerospace and our company designs and builds power distribution and power conversion units running up to 800A at 270DC. We have Chief Engineers that are experts in the area of 28VDC, 115VAC and 270VDC power. Once they see this, they should be able to tell what happened.