Proper Grounding

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What's good Crutchfield? First time poster, long time lurker here.

Having a problem with my Alpine MRV-M1200 cutting in and out at higher volumes and I'm pretty sure it's a ground issue.

My 06 Crown Vic is on hydraulics ergo the enclosure in the trunk moves around a lot - so I thought I'd fix that by lengthening the ground cable to the amplifier to about 5 feet - it's 4 gauge oxygen free copper welding cable - it's grounded to a body panel via nut-bolt copper-lug (I have not sanded it, but hasn't been a problem until now)

I have an Alpine MRV-M1200 - powered with 4ga CCA wire directly to battery - inline fuse is 300 amp - is this too much?

I have a Sony MEX-XB100BT which is powered via 16ga direct runs to battery + and - for ground

I have an Alpine KTP-445U power pack also going to battery + and - directly. (This makes the speakers hum a little bit at higher gains (quarter of the way)

I have not grounded the RCA's.

Can someone tell me if this is a ground loop - improper grounding - what have you? Should I get a ground loop isolator? If I do, do I connect that right before the amp or the head unit?

Thanks for any input,

TehDude

All Replies
  • First off, secure that enclosure, it shouldn't be moving about in the trunk.

    Second, 18" is the maximum "recommended" length to be ran when grounding an amplifier and the shorter, the better. So, mount the amp closer to where you are grounding it and run longer speaker wiring to the sub setup.

    Third, NO 4GA wire I'm aware of can safely support 300AMPS. CCA supports less amperage than pure copper and so you're looking at around 80AMPS for that 4GA CCA wire, give or take. Fire waiting to happen as you have it now.

    Some of the noise in the system could be a result of poor grounding, but at the same time, it could also be improperly set (too high) gains.

    Lastly, why do you have the power pack? That Sony already has a 40RMSx4 amplifier built in it. An extra 5-10RMS per channel shouldn't make a noticeable difference. If you are only powering four speakers, just do away with the power pack. Less links in the chain the better.

  • Thanks for your input.

  • So have you secured that enclosure, shortened your ground, and replaced the 300AMP fuse with an 80AMP?

    Any improvement?

    Really should sand down the body of the car where the ground is mounted, paint is a good insulator.

    Not sure what the sub setup is, but if it's able to thump pretty hard, it may be causing wiring to come loose enough to lose connection.