[Synapticfire]

My front speakers sound great. But while replacing a taillight, I noticed that my subwoofer is not contributing anything.
So I set out to investigate.
It is receiving power. The speakers are moving *slightly*. But not enough to really produce any sound.
I checked the voltage on the orange signal wires. I have an analog multimeter, and sometimes you can see the needle move with the signal.
But since it is line level, I really couldn't tell much.
Also, I pulled the head unit (had to fashion a tool from an old, small hacksaw blade, but that is another post) and reseated all the connectors.

Still, front has lots of bass. Subwoofer has nothing. Even with the fade set to full rear and subwoofer set to +9, nothing.

Anyone have any ideas?
Do the amplifiers go bad in these things? How would I tell?
Could it be a low signal from the head unit?
Does the wiring go straight from the head unit to the subwoofer? Or does it take a detour through the front amps or rear speakers?

Thanks to anyone that can give me any guidance.

 

[Synapticfire]

Sorry, its a 2002 with the dual 6 1/2 inch drivers, and the amp mounted to the bottom of the speakers inside the enclosure.
All stock.

 

[kmagnuss]

Have you pulled it out to see if the speakers have rotted out the surrounds?

 

[ferret]

when you change the sub level on the head unit does the slight movement of the subs change at all?

 

[Synapticfire]

Pulled the whole thing apart, and the speakers appear fine.
I should probably hook them up one at a time to an alternate source, just to be sure.

It is difficult to tell if adjusting the sub level affects much, but cranking the volume does have an affect, albeit, a small one.

 

[ferret]

Doubt this will help but you never know, it's from the main page, did you trace the source cables yet?

Subwoofer Thump: Some owners have experienced a thump heard through subwoofer assembly. There is a connector in the left side kick panel that gets corrosion in it and causes this thump noise. The fix is to put new connector pins in, run a new wire to the subwoofer from the audio head unit, or put jumper wires across the connector

.

 

[Synapticfire]

Thanks for the info, ferret, but I did already see that, and that unfortunately is not it.

I did an experiment with the source wires. I dragged my home theater subwoofer out to the car, and wired it in by cutting the end off an old line level rca cable. Sounded great. So I have signal.

After taking my home audio subwoofer back inside, I removed the amplifier from the range rover subwoofer enclosure, plugged it into the wiring harness, and measured the voltage on the speaker outputs. After years of using a multimeter, I just now learned that you measure audio levels with the meter in the AC voltage position. Makes since. Can't believe I didn't know that already. ( Why am I never as smart as I think I am?)

Anyway, speaker output on the amp is reading a max level of about +4dB. I don't know if that is a decent value or not, as I don't really have a reference.

But I am moving on to the speakers now, which appear fine, but maybe they have a short in the coil or something.
Stay tuned.

Thanks!

 

[kmagnuss]

Those little amps aren't all that powerful to begin with. They're rated, IIRC, at 180 watts or 360 watts depending on the year...and I HIGHLY doubt they put out more than 50 watts (if that) at frequencies under 100 hz.

I would take out the box and remove the speakers to inspect them closer...you may find a small tear or two in the foam surround that you didnt' see before.

Also, to test out the amp, bring out another speaker to the P, and hook it up to the amp directly. There's two sets of speaker wires coming out of the amp, but they're run in parallel, so it doesn't matter which one you use.

 

[Synapticfire]

Figured out the trouble.
The speaker magnets are off center.

This causes the coil to become bound between the center magnet and the side, preventing movement.

I doubt this can be fixed, so new speakers are in order.
I don't know how the first speaker was set off center, but I am to blame for the second.
I did not realize the amp was attached to the back of the speakers when I first tried to take them out, and ended up accidentally using it as a lever that affectively popped the magnet on the other speaker off center.

I've seen that some members have had some success with after-market speakers. Might try that.
Or maybe some speakers from these guys: http://www.roverville.us/

Thanks guys for the support!

 

[kmagnuss]

$159 plus shipping *might* be a little high for a pair of those. I'm not sure that they're factory original. The speakers that I took out of mine were single voice coil, 4 ohm. If you used those, and they are 4 ohm per coil, you would effectively be reducing the impedence to 1 ohm, which will quickly fry the amp. But...if those speakers are 8ohm per coil, it would run them at 2 ohm (like factory) and all is well.
You could run them in series, but then you'd be up to an 8 ohm load, which would reduce your sound level by half. Nobody wants that.

 

[rhino_ed]

Aftermarket amps are cheap and way better.

 

[Synapticfire]

I sent Roverville an email requesting more information.
They seem to have a good reputation on the forum here, and look like they know what they are doing.
I'm interested because they look like they will fit without modification to the box.
I'll let you know what they tell me as far as how to wire up those speakers. Probably using a single coil.

Don't want a new amp though. Old one is fine.

Also, I did on autopsy on one of the dead speakers. Pulled the magnet off the back of the one that failed on its own and it looks like it had a very sparse amount of glue holding it centered. I think the glue just failed. The other one had twice as much glue, but it was definitely degraded. I think it would have failed soon as well.

 

[kmagnuss]

<--- Not a fan of running DVC subs as SVC.

 

[Synapticfire]

<--- Not a fan of running DVC subs as SVC.

Yeah, I'm talking out my ass on that one. Don't know crap about dual voice coil speakers, except what I just learned from Google.

 

[rogan]

If I were you I'd just ring around some wreckers and see what you can get a second hand set for. The factory speakers are cheap and nasty things, definitely not worth $159 /pair. You could go aftermarket and fit something like an Image Dynamics ID10 in a custom mdf box in the factory position, but that would be like fitting a Porsche steering wheel to a Lada. If you can tolerate the factory system then pick up some 2nd hand subs off a wrecker, if you're going aftermarket them go the whole hog and do it properly.