When I am listening to my system & the engine is at lower rpm's and the radiator's electric fan turns on my subwoofer makes some weird bass noises.
system consists of a Freeway DVD-4383NBTi head unit(Canadian Tire Cheapy) Alpine MRP-M500 Mono amp and a single Alpine SWR-1022D subwoofer. I have noticed it a little bit when I use the power windows also.
I have not noticed it at all when driving and at higher rpm's. Can someone help me I have no idea where to start looking to solve this issue.

 

I would say start by checking all of your grounds. Make sure they are clean and no paint. There may be a chance it is the head unit itself. If you have an Ipod get the cable to go from the headphone jack to RCAs and plug that directly into the amp and see if it goes away. Post up the results of those tests and we can go from there.
Nick

 

hey 420guy thanks for a quick response, I know foresure the ground for the amp is good I took it down to bare metal before attaching it. There is a good chance it is from the head unit now that you mention it, I have only started noticing this since the new head unit was installed. now on the back of the new head unit, the subwoofer is only one rca lead not two like im used to, so I had to use a y cable to attach my rca's to the unit. Is this the way it whould have been done? I have never worked with a unit with only the one cable for the subwoofer output. I can take some pictures of the cables on the back of the head unit and the ground connection so you can see how I hooked it all up.

 

If the new radio is tied into the factory wire harness try moving the ground to a better grounding location and see if that helps.

 

Chuck the radiator fan.

 

Agreed replace the ground on the back of the head unit.

 

I will check the ground wire this weekend & I will let you know the outcome.
Also speaking of the head unit ground wire, the park brake wire for the head unit is connected to the ground wire so that the DVD can play while driving without being in park, since I bought it so the kids can watch cartoons while were driving :P could this cause a problem.

 

That shouldn't cause any problems. Easily testable though; disconnect the 'parking brake' wire and see what happens.

If you have an MP3 player (cd player or whatever) pick up a 3.5mm (headphone jack) to RCA cable, and use that for the audio source on the amp(s). Turn the car on, wait for the rad fans, and see if the problem persists. If it does, then you know its not the deck. If it doesn't, then its beyond the amp (RCA cables/deck/ect..)

 

sometimes a ground hum doesn't occur until the electrical system is taxed (AC, lights, subs, )


Usually the item that is new (HU) has the ground issue BUT...
I agree the quality of the radiator fan electrically could be the issue (corrosion, nicked cable)

 

Check the chassis ground.