Ok, my original amp took a dump a while back so I went to Wal-Mart and purchased a cheap amp to replace it. It's only powering one 10" MTX Thunderform 4000 in a Stealthbox style box, so I figured I didn't need anything too spectacular. Everything worked fine until one day about a month later the sub stopped playing. I figured I blew the sub, which was fine since I've had it since the Summer of 2001. I pulled it out and put in a spare (a second MTX Thunderform 4000) and there was no sound. I checked all my wires and connections, all ok. I noticed the protect light was lit on my new amp, so I checked it out. The amp settings are for lows, the bass boost is not turned on, and the gain was about half way up. I turned the gain all the way down and everything worked fine, turned up the gain a bit and it went into 'protect' mode. I was in a bad mood so I yanked it out and borrowed my friends spare amp (similar amp in specs to the one I had in there) and it does the same thing. Why is it doing this? All the connections are solid, what's the deal?

 

OK.....I stopped reading after that.

Specs on the amp would help...and the sub (SVC ??ohm, etc).

 

Check the ground.. I had the same problem on an old one I had.

 

4ohm for each. (4 ohm is what the amp runs at, 4 ohm is what the sub operates at.) Trust me, it's not too much sub for the amp and vice versa. It's small, cheap, and just something to add a little bass to the sound. I'm not into the massive systems like I used to be, that's why I'm not investing a lot of money in this system. I don't want it to shake the car, just add a little thump to the bottom end.

 

See, I tried that as well. I've always had luck grounding it where the rear hatch latches closed. There's a factory ground there and I just bolt it to that. I swapped it around so that it's grounded to where the power antenna is grounded and it still does it. Not really sure why....

 

hey man i had the same problem with my system and i still cant figure it out.
i have a 15 inch crossfire sub its an 800watts and has a fit plug that can be connected at either 2 or 4 ohms. the sub was off the car for about a month because it takes up too much space in the little trunk. then i got it back in the car and it worked fine for about a week then it burned a fuse on the amp.
so then i replaced the fuse and it worked for a few minutes. i then decided to try a spare amp that i had in case of any emergency. by the way the first amp was an american pro 600watts at 4 ohms the speaker was at 2 ohms. the other amp is a concept 100watt at 4 ohms the speaker was at 2 ohms.
but as soon as i connected the speaker the amp would go to protect mode so then i took the speaker out and turned the plug to 8 ohms and it worked fine. but at 2 ohms it was loud and at 8 ohms it sounds nice but its not as it used to be.

 

I would rewire the subs at a higher resitance and see if that fixes the problem

 

If gains were set correctly, voice coil on a sub is not damaged (with result of dramatic impedance drop) the reason can be very poor quality amp.

 

try to disconnect the speakers from the amp, then turn the amp on and see if the protection light comes on.