Subwoofer woes! Please help!

[jimrobbington]

OK, so I have been having problems where my subwoofer is cutting out. Not constant, seems completely random-ish. I will be listening to music and everything is fine, and the bass will just stop. The power light on the amp remains lit suring this "off" period. This doesn't happen when I hit bumps or anything. Sometimes it will come back on. Sometimes it won't happen. Sometimes it happens right away, sometimes after a long time has gone by. It happens at high volumes and low volumes. What can be wrong?

I opened up the sub box to make sure no wires in there were touching, and nothing was. INteresting thing though, is it is a dual voice coil, so directly on the speaker itself, you can have it set to 8 ohm, or bridge it to 2 ohm. i have it bridged to 2 ohm, but the strange thing to me is, the bridge connectors are actually 5amp fuses, which I have never seen a fuse used in such a manner. Anyway, both fuses were blown, (i don't know how I was getting any bass at all with both fuses blown), so I replaced them with 7.5 amp fuses, and still the issue is there. It doesn't seem like there should be enough current going to the speaker to blow those in the first place.

I replaced the amp with a different one (just have an extra laying around), to see if it was the amp, and it still happens with the other amp. The only thing I have left to blame is loose wiring somewhere, but I don't want to tear the whole car down and rewire the bitch! The power lead runs from battery to amp, I am drawing the remote lead off the stock amp wiring, and grounded to the frame in the trunk. RCAs run from the HU to the amp too. I don't know what can be wrong?

[CrtchRktRcr]

Shit Jim, that sounds frustrating. I was giong to say it may be overheating depending on where you have the amp, but it sounds like it happens right when you start the car also. I haven't seen fuses in a sub before (then again I haven't been big into systems in like 10years) what type of sub? Must be pretty high end. You know as well as I do that it's the wiring somewhere or the sub itself.

[BASARAB]

sub is bad?

[jimrobbington]

It's a fairly new sub, maybe 1 1/2 years old. Boston Acoustic 12". The speaker is rated to something like 500 watts, and I only have a 200watt amp, so I don't know how the speaker could have gone bad. I do have an extra 12" laying around, I could see if that swap will help. Visually, the speaker appears fine, and when working properly, there is no buzzing or crackling in the sound.

[earthtodan]

My theory is a bad RCA to the sub amp. A bad solder will cut in and out with just the right kind of vibration, or seemingly randomly. If your RCA is buried under carpet, you can test this by running an RCA through the interior without having to actually replace the original one.

[nath]

have you tried putting a multimeter across the coils to see if they are both the same impedance ??? you may have possibly damaged one or both of the coils

its actually easier to blow or do damage with a small amplifier than it is with a large one

a small amplifier can only produce so much power without going into whats known as "clipping" this is where the power is still increasing but the signal is no longer clean and is distorted
at the opposite end of the scale a large output amplifier will still be well within its limits even when driving the sub with more than its reccomended input

[steel2040]

so you say the amp still stays on when the sub seems to stop I too would say it could be the rca's and just like what they say running the new wires or what I did with mine was hook my iphone directly to the amp with the componet out harness it was the rcas bought some better ones.

[jimrobbington]

Ok, so I swapped woofers and haven't had the issue recur yet... I haven't driven it very long though, so we'll see. Next step well be the rcas if it happens again. With all this speaker removing, I have lost the seal in my box, and the holes are stripped. Where is the best cheap place to buy sealed boxes?

[earthtodan]

Don't buy a new box, use T-nuts. http://en.wikipedia.org/wiki/T-nut

[BASARAB]

I bought this, no complaints http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=330583437159&ssPageName=STRK:MEWNX:IT

[nath]

t nuts are fine until they rip out the wood at the back of the enclosure and you get the bolt stuck completly
a lot of guys on the european car audio competition scene use threaded inserts instead as they can effectivly be screwed into the back of the wood and then removed and glued in place giving a fitting which is re-useable which has a machne thread on the inside and is self tightening

[bigred875]

Ok, so I swapped woofers and haven't had the issue recur yet... I haven't driven it very long though, so we'll see. Next step well be the rcas if it happens again. With all this speaker removing, I have lost the seal in my box, and the holes are stripped. Where is the best cheap place to buy sealed boxes?if it is isn't/wasn' a loose connection somewhere I think you have(had) and impedance/clipping issue. It is reoccurs I would measure the impedance coming out of the box and verify that with what you amp can handle. I bet if you swing through a local audio shop they would help you diagnosis the problem.

have you tried rotating the speakers and drilling new holes to fix your seal problem? Also, there are other options. You can get some but inserts at lowes that dig into the box from behindand hold the sub in place with a machined screw. I forget what they are called though lol ebay has decent boxes for cheap as well

[jimrobbington]

Thanks for the input guys. I haven't had a problem with the swapped sub, so I think the problem was the speaker itself.