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info: phoenix gold mono amp, 1500W max, 750 RMS, wired with cheap 4 ga. wires
alpine type-R 12" sub, same watts as amp, in a ported box

pounded hard most of the time, but would cut out from time to time from wiring faults. the idiot that installed it [me] was lazy, and i thought i finally had all the kinks worked out.

well now it stopped working. no idea why. i've checked ALL the wiring and it's right. the light on the amp lights up, so it's getting power. i've opened the sub box and re-connected the wires, replaced the speaker wire between the amp and sub box, checked the fuses in the amp and fuse holder, took it off the battery and re-connected it for better contact.

all i can think of is either the amp or sub is fried, but i have no idea why that would be. something i may have missed?

Ohm test the sub.

I second that...make sure your sub isn't blown by checking the resistance across the terminals using a multi-meter.

If you don't have continuity, then your sub is probably blown. You have to check right on the speaker terminals themselves as opposed to checking at the speaker box terminals in order to rule out any wiring faults.

crap, i really hope it's not blown. i will check that tomorrow

nicklikesmilk wrote:pounded hard most of the time, but would cut out from time to time from wiring faults. the idiot that installed it [me] was lazy, and i thought i finally had all the kinks worked out.

Just hope this didn't cause the amp to burn a transistor. What sort of wiring faults did you have? Were they on the power side or the speaker output?

power, the remote came undone once or twice, and the ground did once when i took a hard corner.

i pulled the sub out today, and tried ohm testing the terminals, and got nothing.

Did you get 0 ohms on the sub or max ohms?

another way to test the sub is with a battery...

connect the negative from a 9 volt or 12 volt battery to the negative on the sub...

then connect the positive wire to the positive on the sub and with the other end of the positive wire tap the positive on the battery with it..

if your subs makes a poppin sound and the cone moves when you touch the positive to the battery then its still good.. but if the sub makes no sound and no movement the its 100% blown..........

Test the amp to rule it/wiring out, hook it up to another driver/speaker. Can be car-fi, home audio, whatever.

Just do it low to moderate volume, to keep power output down.

Are you putting the voltmeter directly on the driver, or on the wires in the box? One time I had a bad input hookup on the box I built. Hooked up the driver only to the amp to make sure i was good on the wiring, and it was. Put driver in box, and it sends the amp into protection mode anytime it's putting out a few watts. Pulled out my driver, and it still played fine, put a new terminal in the side of my box, and it was still fine.

myfirstbonnie wrote:Did you get 0 ohms on the sub or max ohms?

0 ohms, needle didn't even move

i will do both of those ideas today so i can isolate the problem. i took the sub out of the box and tested it right on the terminals.

i tried the 9V battery idea, and it made no noise. that was a $220 speaker.

0 ohms is a good sign the sub is good. It is basically a coil of wire and should read very low. A very high reading would show an open coil. I would suggest the same as above and try another speaker on the amp. I would put my money on your amp being bad.

Shouldn't the sub have 4 or 8 ohms?

nicklikesmilk wrote:0 ohms, needle didn't even move

Using an analog meter, 4-8 ohms will not move much if at all. If it was a true short and the amp was working, it "should" have tripped the amps circuit. He could even have a shorted sub that popped the amp at the same time.

My personal opinion is when he had an intermittent ground and remote on lead to his amp, it caused the amp to blow.

If the needle didn't even move when you probed the speaker contacts with the meter, then it it should indicate infinite resistance as opposed to zero, which sounds like the speaker is bad to me. If it did in fact go to zero, there there's a good chance that the the speaker shorted internally, which also means a bad speaker. A decent meter should easily be able to indicate the difference between zero and four ohms as long as you have the range selected properly.

Try another speaker on your amp and see what happens.

edit: check the leads that run from your speakers terminals into the cone (voice coil) for any damage, or bad solder joints.

yeah, i have the cheap analog multimeter, it didn't do anything. my buddy touched the sub and said it was still good because the cone wasn't making any noise when he pushed down on the speaker. haven't gotten around to trying the amp on another speaker, but that is definitely next. otherwise i may just unhook my amp and put it in my friend's setup that i know for sure works.

Pushing on the cone and listening for noise is not a definitive way of telling whether or not the sub is bad. That said, if it DID make noise, that would be bad, but just because it didn't, doesn't mean it's not blown. It could still be a problem external to the voice coil like I mentioned earlier with the lead wires running from the speakers terminals to the coils. If that is the case, the speaker would show infinite resistance, and would still not make any weird noise when pushing on the cone.

The best thing to do is testing your amp with another speaker, but also test your speaker (the one that may be blown) with another amp (even a home entertainment system will suffice for this test). That will definitively tell you where the problem lies.

Have you made sure that your signal wires from your HU to the amp are all connected good, and that you don't have a sub attenuation feature enabled on your HU or something simple like that?

As a side note, even on a cheap analog meter, the "infinite" and "zero" readings for resistance will be on opposite sides of the gauge, so if you came up with "zero" ohms, then the needle would have had to sweep all the way across the gauge to the "zero" reading, but you said it didn't move at all. To make sure your meter is working, just turn it on and touch the two test leads together and the needle should swing all the way over to "zero".

nicklikesmilk wrote:
i tried the 9V battery idea, and it made no noise. that was a $220 speaker.

You can get Type R's much cheaper than $220 now. If it is blown there are much better speakers you can get for $220.

My friend let me use his subwoofer in my car right on my amp, and it worked. so the amp and all its connections are still good, the problem definitely lies in the sub itself. I'm gonna take it to an electronics place and see if there's a way to fix it. Someone told me that it's possible some internals in the sub just need re-soldering. If it'll be cheap enough to fix, i'll keep it. otherwise whenever i get money, hopefully by the end of the summer, i'll just spring for a new sub.

I'm not certain on how to read the ohms on my multimeter. All i can tell you for sure is the needle didn't move at all when i touched the terminals, and the sub didn't do anything in my friend's amp that i know works.

If the needle didn't move at all, that means that there is a broken connection somewhere on the sub. If the problem is the voice coil (internal) then it's probably not repairable for a reasonable cost. If the problem is the leads to the voice coil, then it MAY be repairable, and if it is, it should be pretty cheap. Basically, if you can identify where the problem is by looking over all the wires, then it's probably repairable. If there's no visible damage, then the problem is internal and you'll probably be buying a new sub.

there aren't really any visible wires on the outside of the sub. just the ones on the terminals and they look alright.