frustrated with amp or sub problem(s)

I got a new-to-me car recently and was all excited to put in a sub in the trunk to augment the dismal factory mid speakers.

I got a cheap 200W 2-channel amp and a hand-me-down dual-voice-coil Bazooka tube (tested them before I went through installing all the way, and they sounded good). Got them put in with all-new wiring and then the following day I noticed the amp would kick into protect mode time to time. There was not a specific reason I could tell (i.e. not overheating).

To test the set-up, and see if I had a bad amp, I wired up a different amp of the same output rating and number of channels, and it too sounded OK then it started acting up and going into protect mode.

I thought *ah-ha* maybe I have a faulty voice coil on the subs or bad speaker wiring. I swapped out for a different sub and speaker wiring but still no change.

I finally checked the ground connection (twice!) and the other hook-ups to be certain I didn't overlook something.

Finally, I dig out a volt meter and see that with the power on the radio and car completely off, the amp gets between 8-10 volts at the 12V input. When the radio is on (and ignition off -- it's an odd Blaupunkt HU that lets you turn it on for an hour with the ignition off) the amp 12V power input is around 2V!

I guess what I'm leading up to is:
1) does this reading mean the ground could still be bad?
2) does this mean possibly there's a bare portion of the 12V power wire?
3) does this mean I could have 2 bad amps and bad subs?
4) could it be all of these and/or other problems?


Any help you might have would be great!

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Check the volts on both sides of the inline fuse (you should have one) to see if there is something wrong with it. If volts are good on batt. side but not on amps side you know it is that:) Do recheck the ground as well.

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 how'd I miss this?

I did what you suggested Donsway.

I used my voltmeter to check the volts at the battery and pre-fuse (40A). I got better than 12 volts in each case. Then I pulled the fuse out just to check it. I noticed it had some carbon or other "schmutz" on it. I cleaned it off and stuck it back in.

I then tested the post-fuse volts and got 12 or better. I also again tested the power wire at the amp and this time got a constant 12V or better.

I fired up the amp with no problems and plenty of power. I guess this might mean somehow the fuse was gunked up in some way as to impede the electrical flow. I was wondering if the blade type fuses provided in the wiring kits are sometimes crappy and/or whether I may have somehow caused this to happen? The wires and fuse were brand new.

Of course, I did make a triple check of the ground and now have a quarter-sized bare metal spot for the ground to seat-up against it.

Thanks for the suggestions, Donsway! I'm glad not to be listening any more to a system that thumps like an empty cereal box tumbling down the stairs!

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Don't know if I am reading it correctly, but I had the same problem (my amp going into protect mode) and it turned out that my subs where wired wrong. I had a 4dvc sub that was wired to 8 ohms, the amp kept going into protect mode because of it. So if that doesn't work, check how your sub is wired inside the box, here is the link for the wiring guide... I'm pretty new at this audio stuff, just thought I'd tell ya my 2 cents on the matter.......... wiring guide .... http://www.cardomain.com/shop/category/subwoofers at the bottom of the paige there is a link on the right hand side that says "Subwoofer Wiring Guide" click it. Good luck finding the solution to the problem.

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