amp question

i have a 10" infinity sub and a MTX Thunder amp that i have had for a while and just recently put in my car. When i turn on my radio the sub hums and doesnt stop, i was told i need a better ground for the amp. So i was wondering where the best place to ground the amp would be? i have a 96' impreza brighton.

 

Ground it to metal! HAHA J/K I find that it works best if you find an area not seen, like under carpet. Take sandpaper and sand off the paint till you see shiney metal, drill a hole and screw down your ground wire! CHECK WHERE YOUR GAS TANK IS FIRST!!! (learned that the hard way on my girlfriends car!! HAHAHAHAHA)

 

Before you go drilling holes in you're car, disconnect the inputs to the amp, and see if it still hums. If the hum stops, the hum is coming from the head unit, or is getting picked up through the signal cables.

If you look around, you may be able to find a factory ground spot, which would probably have a threaded socket.
If nothing else, ideally, you want to make a ground to the most substantial (frame rail) metal you can, then see directions in previous post.

 

haha ok thanks, does it matter where in the trunk in ground it or will anywhere work?

 

ground it to a bolt that holds your rear seat down.

 

ok ill try unplugging the inputs, if it still hums should i re route the wires or is the headunit bad?

 

i already did that and it still hums.

 

Can't say for sure. one way to find out would be to hook up another source if you can.
Are you using shielded cables?

 

all of the cables are shielded except the remote wire going from the deck to the amp

 

Does the humming get louder or higher in pitch if the car is running and you give it some gas??

 

no, just the same pitch all the time.

 

That rings a bell as well, (been 4-5 years since working with audio) I think I remember I had noise traveling down the turn on lead once, if you think that may be it, try another +12v source for the turn on.

 

There are really a few things to check for a hum. In a subwoofer situation, it's a little easier than speakers to track down, so you're lucky there.

I doubt you're getting engine whine. If so, I would definatly re-run your RCAs. If that doesn't fix it, I'd check the ground cable on your battery.

Are you using an aftermarket head-unit, or a factory one with a line out converter??

If you're using an aftermarket head-unit, then yes, check your ground in your trunk. Are your power and ground wires the same size? How many watts (RMS) is your amp? I usually sand off the floor of the trunk, then run a screw with some star washers into the floor. Then, I put another screw on each side of the ring terminal to keep it from loosening/twisting.

If you're using a factory head-unit, check your wiring for your line out converter. Also, check the gain adjustment on the line out converter. If thats too high, it would induce a hum. If your line out converter has ground wires on it (usually black or brown), ground them.

If non of those work, lemme' know...

 

i am using an aftermarket pioneer headunit, the amp is 250 RMS bridged at 4 OHMS and i think the pos. cable is 8 gauge and the ground might be 6. (it looks to be a little thicker)

 

Hmmm....is it a "wal-mart" amp kit??

where is the amp grounded right now?? What's your gain setting at??

 

no, i got the power cable from a friend at Ultimate electronics, it is grounded to one of the rear seat mounts that i roughed up a little bit with a file, and i think the gain is almost all the way down.