hiredgoon

OK so I just bought a new amp to replace my PG XS2200, its a MTX Thunder 304. I didn't have any noise problems with the XS2200, but now, I am getting what sounds like fuel pump and/or sending unit (faint whine) and noise from the brake lights (clicks).

I've already determined that the noise is not produced from the amp. I used muting plugs on my inputs and the noise went away. Because of that I tried switching the RCA cables (assuming they were pooched) and ran it through my interior (away from any other wires) but the noise was still there. I also tried switching the inputs from front to rear which didn't make a difference.

Now I'm confused

hiredgoon

I don't have any processing units (its a simple system only one amp, 1 sub...)

The amp is grounded to an existing bolt in the trunk, using the same spot as the PG was grounded to. and the ground area was sanded down to bare metal.

1st MP3 in NH

If a muting plug makes it go away then its coming in through the RCAs. You may have a bad amp.

douggie

Are you using the stock HU? if yes, then check the ground on the HU. Might even want to tap a new ground and forget the ground wire in the factory harness.

For me, upgrading RCAs reduced the amount of alternator noice significantly. Might want to get some unshielded twisted pair RCAs.

1st MP3 in NH

Hold the hell on their, where are you getting the noise from the sub? Or are you using a 4 channel amp powering sub and speakers?

hiredgoon

That was just an example...I'm using a component set up front and the noise is coming from the tweeters (obviously because everything else is low-passed) And I'm using a Panasonic HU. The sub is running off the rear channels bridged and the components are running stereo of the front channels.

It might have something to do that I pinched the power wire between a couple pieced of wood. although the insulation is still intact so I dont know if that would induct noise or not.

I thought if the noise stopped with a muting plug the noise is coming from somewhere upstream of the amp right?

I've had alternator noise on other amps and that was just a quick touch up with solder on the inputs. But this aint alternator noise.

I'm going to try upgrading the power and ground up to 4 gauge tonight see if that helps (I was running 2 amps so I have 4 ga input and 8 ga coming out of a distrobution block)

1st MP3 in NH

It sounds like accesory noise, brke pop and such. WHat is amplified in the car. If you have though the front speakers and you not amping them thenit sounds like the amp is back feeding it trough the RCAs. It isn't easiy to get accesory noise though a head unit on ly through an outboard amp. If you pinched the power power then that won't cause it but sometimes apower wire running passed noisey electronics, ie fuel pumps and fuse boxes can. Also most amps have filter for the power wire so that rarely were it comes from. THe ground wire and the RCAs are almost always at fualt. Measure the impedance of the ground point back to the negative battery terminal, should be less then.3 ohms. Also check that you ran the RCA's the right direction some have arrows on themindicating signal flow. Basicly these type drop te shield on one side.

Can you describe your entire setup including ground points and wire paths please?

hiredgoon

OK here we go with the wiring.

Battery - Motomaster with Stinger battery terminals on + and -
Battery ground upgraded to 4 ga to shock tower bolt
4 ga wire through 60 amp AGU fuse, then through firewall. (Yes I know I should have ANL fuse I am working on that)

Power wire runs under center console and under rear seat cushion to trunk, to distrubition block with 8 ga outputs (1 being used)

RCA cables-subwoofer out running under center console as well
front out running down drivers side under sail panels

Amp ground - back trunk panel between rear lights using existing bolt there is another unused wire that I used for another amp on another existing bolt on the same panel but it is taped over.

I dunno if theres much more I could say about the wiring,,,and unfortunately I do not own a multi meter

I have a component set and a single subwoofer running off the MTX amp, and rear coaxial speakers running off the HU.

1st MP3 in NH

1st MP3 in NH

If it the right amperage then there is no need to do an ANL

Power should be run on the side not the middle, as far from both RCA's as possible

Move the RCAs for the sub to the sides, since you have an amp also playing high pass the input stage of th highs can be corrupted by the RCAs running next to the power wire. NO RCA'S should be within 18 inches of the power wire unless you only have a sub amp in the system.

The amp ground needs to be on a primary body panel ie floor, paint should be removed then attached. If you have to use a bolt use the seat belt bolt. Also you want the ground far away from accesory ground points not at the same place. The ground shoulod be 4 guage since its what runs through the car but you could get away with 8.

hiredgoon

So I should move the sub RCA's to the side...ah man that was a pain in the butt to get em in there! LOL. I'm not moving the power wire that was even harder to get in.

And I am going to get a 4 gauge ground for the amp its just common sense...I got to make a trip to the local shop to get barrier strip terminals. Maybe a seat bolt would be a better idea but theres got to be some reason I didnt use it the first time...

And my amp has 3-25 amp fuses so an ANL fuseholder is the only way I would get full points in local SQ comps.

Thanks for your help bro now I need to find a time that I can actually work on it (damn homework and part time job)

1st MP3 in NH

If the 60 amp fuse doesn't blow then you don't need a bigger one. If you draw 61 amps it will pop it will never just drag down the system. 3 fuses on a 4 channel amp? thats a little strange.

1st MP3 in NH

I understand the need of smaller multiple fuses, but typicly it will be 2 on a 2 channel and four on a four channel not 3 on a 4 channel

hiredgoon

Yeah so I just disconnected the sub-out from the amp...NO NOISE! LOL damn now I feel like an idiot. I bet the noise was always there, just couldn't hear it before because I was using 2 seperate amps. So temporarily I clicked on my "2-ch" feature so I can still have bass until I take apart my center console.

Thanks MP3

1st MP3 in NH

If your amp is the MTX 6304 then just press in the RCA input switch to the 2ch position that way it will take what ever is plugged into the front RCAs and send it to all channels.