No sound from Subwoofer/amp other than at very low volume

[cgorman21]

I have an Alpine CDE143BT head unit, a Rockford Fosgate P400-4 4 channel amp running four speakers, and an Alpine mrp-m450 mono amp powering 2 8" JBL GTO804 (4 ohm SVC) subs. The subs are wired parallel at 2 ohms. The whole system worked great until a few days ago, now about 90% of the time (once in a while it works fine) the subs make no sound. The amp turns on and off with ignition or by head unit, grounding and power seem fine (scraped and grounded to a new surface and no change). When the volume is extremely low i can feel the subs working with my hand, but as soon as it gets loud enough to be audible they turn off completely. Does anyone know what my issue could be? I checked all connections and they seem fine. the rca's going into the amp have signal (worked when plugged into other amp). I used monster 12 ga speaker wire to go from amp to bananas on box and within the box, is this the wrong choice? Could that be causing the problem? Thanks in advance for your help.

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[jrdnhsnbrg 10+ year member]

Typically banana plugs are pointless. I just used 2 bolts, washers, O rings, and nuts on the end to hold it all together, obviously. Check your fuses connection, they can get fairly corroded if you drive in wet weather. That happened to me so I switched to all ANL-style fuses. Check the on-amp fuses, too.

 

[Side Show 10+ year member]

^^ this guy, check your fuses... also see if your amp is going into protection..... subs may be wired wrong, also check your amp and deck settings...could be due to clipping

 

[jrdnhsnbrg 10+ year member]

Wooo //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif feels good to have a caraudio.com vet endorse my suggestion //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[cgorman21]

Thanks guys, all the fuses look fine. I'm not sure if it is going into protection mode, the LED is steady blue as normal, not blinking at all. The wiring worked fine for a few months. They are ran parallel for a 2 ohm load, the amp is 2 ohm stable. What settings would be causing clipping? How would I eliminate that or tell if that's the problem?

 

[jrdnhsnbrg 10+ year member]

What is your gain set at? Turn it down all the way and slowly turn it up as if you were tuning the amp up to the point where the sound shuts off or you see the excursion stop increasing then turn it down juuust a tad. This is with your HU at the loudest volume you'd listen to it at.

 

[cgorman21]

Its turning off when it is very very low. Barely audible.

 

[jrdnhsnbrg 10+ year member]

Turn the gain on the amp all the way down then continue as I said before, your gain might be set too high.