Strange Sound from Sub

[smms25 10+ year member]

Need some help figuring out my problem. First, thanks to anyone who gives me some advice.

I installed Alpine MRD-300 ( http://cartoys.com/cartoy/pdfs/mrdm300_manual.pdf )

w/ 8 gauge kit as recommended into my 08 Mazda 3 with stock headunit. I used a David Navone Engineering LOC... the sub is a MTX Thunder 12" 4500 SVC ,TA4125 (model number)... in a sealed eclosure(1.25 cubic feet)

the amp powers up fine with no code whatsoever. With key on, engine off... 11.8-12.0 volts.... with engine on 13.7-13.9 volts. So good power.

I redid some connections I thought were bad, and Im going to get banana plugs for my speaker terminals instead of using bare wire.

The Issue: the sub does respond to bass, it has output though not very much, but it sounds muffled or blatty. Hard to explain the noise, but something is wrong, so thats my best description. Any help greatly appreciated

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[AlterEgo99 5,000+ posts]

How do you have the settings on the amp? How are you connecting the HU to the amp?

 

[thegreatestpenn 5,000+ posts]

either bad RCAs or the sub settings are fuxed.

 

[smms25 10+ year member]

I didnt connect the head unit to the amp... I use a LOC , which I tapped in from the rear passenger side speakers.

If the RCA's arent bad, what amp settings should I check and change

 

[theMessenjah44 10+ year member]

could be the LOC, did you solder all your connections? they're not great in the first place, but if you don't have good connections, you can ufk it up in a big way

 

[jpexpc 10+ year member]

Make sure if you hooked up L & R for the LOC that you wired them the same. If you have the inputs in your LOC different it would put your amp out of phase. If you don't know how to check just take one side of the LOC and wire it just the opposite of the way it is.