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My JL Audio sub is dead. What exactly happened?

So at my wife's request, I hooked up a Roku to my main system. Roku is a device for internet streaming movies and tv. The connection between the Roku and my preamp, a Meridian G68, was a 12 foot optical cable.

The first night, I hook up the Roku and it works perfectly.

The next night, I move some cables around, then I hook up the Roku again, exactly the same way as the previous evening. I get picture but no sound. Weird. I pondering what I might have done wrong when out of the speakers... POP. POP! POP!!!

Uh oh.

I dive for the amps, switch them off. The POPs stop immediately. But...

Now there's a TERRIFYING HIGH PITCHED PULSATING NOISE coming from somewhere in the room. I finally realize it's coming from the sub, a JL Audio Fathom 113. I dart across the room, switch it off.

I stand frozen, savoring the final moments of the fantasy that maybe things aren't that bad.

Here are some questions in no particular order...

1. I suspect the amp in the sub is fried. Does that sound right?

2. Where did those POPs come from? Could a damaged optical cable do it? Or maybe the optical cable wasn't fully seated?

3. Do I really have to ship this 150 pound sub to Florida? Or do you think there's any chance of finding someone local to fix it? (I'm in L.A.) The sub is out of warranty, btw.

4. I tried to take the panel off the rear of the amp (I know, lethal voltages inside) with the thought that maybe I would just bring the amp portion of the sub to someone local to fix. I removed about 12 screws from the rear panel and still it doesn't budge. Why can't I open this thing?

If you have any suggestions, I'm all ears. If not, thanks for reading.

Bryon

P.S. The rest of the system appears to be fine.
bryoncunningham
mapman's avatar
mapman
22,334 posts
 
Hopefully, whatever the problem is is isolated to one device but I wonder why there was NO sound including from the speakers?

Might the sub have been mainly a victim of something else upstream? If you jostled wires in the process the second time, I would say speaker wire connections are most exposed and vulnerable and the first suspect usually. That would most likely effect speakers and/or sub and/or amp. Amp might have a blown fuse. Check those if you have not already.

HArd to outrule anything for me at this point until isolated via regression tests piece by piece somehow.

I hate when these things happen so I empathize with you.
westborn
156 posts
 
YOU KILLED IT MAN !
bryoncunningham OP
890 posts
 
Hi Mapman - Thanks for your empathy. I agree it's a puzzle. I don't think it was a speaker wire mishap, but I can see why you would speculate that. It's a little strange that the only thing that got damaged was the sub.

Now that the JL people have told me that the gasket for the rear panel is probably fused to the paint, I'm going to make another attempt to open the sub. First I'm going to drill holes in the external heat sinks and thread a wire or a bolt through, to create improvised handles so I can get some leverage.

I'll let you guys know if I manage to get it open, and if so, what I see.

Bryon
chadeffect
586 posts
 
Careful drilling holes in heat sinks. I suspect that metal is brittle.

Is there not a way to slide out the front panel then use a long lever to push back plate off?

Or even remove the woofer to do same idea?
bryoncunningham OP
890 posts
 
Hey Chad - I was careful drilling and nothing broke. I threaded bolts through the holes, which gave me enough leverage to pull the back panel free from the gasket.

I removed the entire back panel from the sub, which includes the amp and the transformer. Nothing is obviously fried. I guess I was hoping to see something burnt to a crisp so I could simply replace it myself. I know that's silly.

The folks at JL are graciously trying to help me find a local repairman who can diagnose and fix the problem.

I'll update when I know more.

Bryon
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