500/1 turns on and off at high volumes

What happened right before it stopped working?

how do you have the speakers wired to the amp.

They should be wired in series (to arrive at 4ohms) and bridged at the amp.

just a tad is all that it takes to throw it in protect mode so check the gain and the cross over and make sure they are set at a decent level and see if that works a little bit

Check the wires going to the amp for any corrosion on the terminals and ground.

. Kind of like when someone squeezes a garden hose when your trying to use it. That would be the high volume, starving the amplifier. The capacitor stores power in it to power the amp at high volume. 2 farads would probably be bulletproof on a single amplifier system, but 1 farad should work well enough. Or seek help from an expert on exactly what size capacitor you should use. If you find yourself saying: My amp cuts out.

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Check to be sure you are on the correct outputs on the head unit, and be sure the outputs do not have a separate volume control.

you may have burned the channel you were using..try taking the cover off the amp and checkin for burned spots or any wires that may be loose or touching within the amp.

I would try running the subs in parallel. Pos to Pos Dual Voice, Neg to Neg Dual Voice. Then Run + to + stereo - to - stereo on both channels.
So you have + and - running to one channel and + and - running to the other channel.
Also your LPF filter could be set too high.

Check the wires for a lose connection or corrosion. You may need a capacitor.

Basically, at low power the amplifier is not asking for a lot of power from the electrical system to power your sub woofer. For lack of a better term and probably the best way to explain it is. It uses up all the power in the wires leading to it at a high volume, and has to wait for more. Kind of like when someone squeezes a garden hose when your trying to use it. That would be the high volume, starving the amplifier. The capacitor stores power in it to power the amp at high volume. 2 farads would probably be bulletproof on a single amplifier system, but 1 farad should work well enough. Or seek help from an expert on exactly what size capacitor you should use. If you find yourself saying: My amp cuts out.

If this assisted in solving your problem, please take the time to rate it. Thank you.

ok what is the amp out put of your altanator and were did you hook the romte turn on wire two. It is usally blue.

There should be a small switch someware on the amp marked VOX or normal. I bet its on vox. if there is no switch then theres a jumper inside the unit to put it into a vox state. Vox Is when audio is at the input the amp goes on and when theres no voltage at the input the amp switches off.