Sub/Amp Intermittent Failing

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So recently esp when im drivng the sub cuts out, i have a sub switch using the remote wire, turning this on and off does nothing. The only thing that fixes it sometimes is cranking it up quite loud, which is a pain in the ass. im not sure what to look for to try fix this, wether it's an amp or headunit prob. Any ideas??

Sony xplod 12" Silver pentagon sub
Cheap shitty Powervox amp, bought 3 years ago never had a prob with it.....

Let me know!

[mr30%jr]

is the power light actually on, on the amp prolly just a loose connection between sub and amp... when your turning it up really loud your effectivly probally arcing the loose conection over so it works.check these all, unless you have a dying sub which can happen when the flexxy wire on some cheap subs fails between the cone and basket.

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Ok, replaced both terminals from amp to sub, see if this works. Seems to happen when going over bumps more so then not but we'll see how it goes.. Cheers

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Noticed on the way home that front left speaker stopped going intermittently as well. My speakers arnt running through the amp so im thinkning it may be headunit related?

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Ok amp still has power when sub stops working.. is there anyway i can test the rca leads? Pulled headunit out and played with leads in the back and still nothing.... anyone have any ideas for me??