What Could Be Wrong?

[poisoned10 10+ year member]

I have been having problems with my system and I'm not really sure where the problem lies.

My amp will cut in and out of protect mode with a blinking protect mode light. According to the JL Audio manual that means its either running at an impedance lower than it can handle or the power source is below 8.5v.

I just checked it while it was in protect mode and the voltage was 13.3v. So that leads me to believe that the sub is running lower than 2 ohms. It is a 4 ohm DVC that is wired in parellel to 2 ohms. I've been told that when a sub is going bad that it sometimes will run at a lower impedance than what it normally would. Is this likely the problem? Sometimes it will run for 20 minutes with no problems and other times it will run for 5 minutes.

I've done the big 3, checked all wires (especially the grounds), have gains set properly, checked to make sure amp isnt over heating, etc.

So am I looking at a failing sub or bad amp or combo of both?

Thanks for any and all input.

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[keep_hope_alive Premium Member]

where did you measure voltage at when the sub cuts out? you should measure it at the amp terminals themselves. pics of your grounds and connections?

 

[poisoned10 10+ year member]

That's where I measured it on the amp terminals. But it wasn't as it cut out, it was after they had cut out for a while and never came back on.

Also, when the light flashes on the amp I can hear some feedback coming from the sub. Just a small bump and it's only as the light flashes.

I'm on my phone at work right now so I can't get pictures uploaded right now. My ground to my amp is connected by 2 screws behind the back seat directly to the chassis and I sanded the paint away with a wire brush.

Right now I have it wired in parellel with both + and - coming from the same voice coil. I'm going to re-wire it so that the + comes from 1 and the - comes from the other, even though it probably won't help at all.

 

[musical_high 10+ year member]

I'm no expert but did you check the sub's resistance?

 

[06goat 10+ year member]

I'm no expert but did you check the sub's resistance?

This, pull the speaker wire for your sub out of the amp and see what It reads.

 

[poisoned10 10+ year member]

I'm no expert but did you check the sub's resistance?

I have not. I will have to Google how to do that after work when I move the wires over. I assume testing resistance will tell me what ohm the sub is running at?

 

[poisoned10 10+ year member]

Ok, so if I'm understanding this correctly, I set the DMM to ohms and connect it to the terminals on the back of the sub with the amp powered on and the reading will tell me about what my sub is running at?

 

[daboyfrumdabx 10+ year member]

You'll want the sub disconnected from the amp. You want the reading from the sub at rest.

 

[poisoned10 10+ year member]

You'll want the sub disconnected from the amp. You want the reading from the sub at rest.

Oh, ok. Thanks!

When I get off work tonight and pull the sub out I'll test it before and after I switch the wires, just in case there is any difference, even though I know it's unlikely.

 

[poisoned10 10+ year member]

So I set my DMM to ohms (200) and it was consistantly around 1.8/1.9 with the bottom hitting 1.7 and the max hitting 2.0. So I'm assuming the sub is running about right?

 

[poisoned10 10+ year member]

When I was re-doing the wires from the terminals of the box to the sub the amp kept going into protect mode. Did it probably 4 or 5 times. I'm now wondering if maybe there is something going on with the speaker wire terminal on the box? After the 2nd time it went into protect mode I checked the voltage and it was a little over 13v.

I may just remove that speaker terminal and run the wires directly from the sub to the amp and see if that makes any difference.

On that note, would that be too big of a hole in the box? It's already ported.

 

[brooklynjoy2008 10+ year member]

When you connect or disconnect ANYTHING your car should be off, stereo off, amp off. If you are messing with the power or ground wires you should remove the fuse from the power wire at the battery. I have a feeling I have been playing with amps as long as you have been alive, so I didnt have the internet I learned the hard way. As for your problem try turning your gain down a little and see if it still does it.

 

[brooklynjoy2008 10+ year member]

Also after thinking about it did you have the fuse in the holder when you connected the power and ground wires?

 

[poisoned10 10+ year member]

When you connect or disconnect ANYTHING your car should be off, stereo off, amp off. If you are messing with the power or ground wires you should remove the fuse from the power wire at the battery. I have a feeling I have been playing with amps as long as you have been alive, so I didnt have the internet I learned the hard way. As for your problem try turning your gain down a little and see if it still does it.

The only reason I had the car on is to warm it up before I left work because it was cold outside. The radio was turned off and I unplugged the RCAs so there wouldn't be any signal going to the sub as I wired it.

I may be a noob to car audio, but not so much that I don't know to pull the fuse when messing with the power and ground wires.

 

[poisoned10 10+ year member]

Also after thinking about it did you have the fuse in the holder when you connected the power and ground wires?

I definitely did not. That was the VERY last thing I did when I did the installation.

But like I said, I had the RCAs pulled and sometimes when I would touch the wire from the speaker. I'd to the amp, it would put it in protect mode. Which is why I thought that it could possibly be that.