A common question for all car audio enthusiasts is – how do I stop my subs humming?

The first thing you need to establish is where the hum is coming from and there are a few ways you can test this.

Unhook the RCA to the amp, but leave everything connected so the amp will turn on and receive power, but not signal. If the humming is still there, it means that you have a bad ground loop. To resolve this, you can purchase a Ground Loop Isolator, which enables all the grounding in your car to be grounded at one contact point.

Another reason is that your power and RCA cables might be running too close together (if not together entirely), causing feedback.


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Highland J

Joined: Sep 08 2006
Posts: 1157
Location: ND, Land of the covered wagons and wheat.
Post Thu Apr 23, 2009 8:28 am

So its been this way for about a year and ive always just ignored it which prolly made it worse. The installer told me that it was because my deck was a “cheap” deck and didnt work well with the subs but every friend i have who isnt clueless on subs agrees that they **** up my install by possibly looping a wire or something. When Im driving the hum goes away but say i stop (park gear or not) the longer i stay parked the louder the hum gets! its the most annoying thing under the sun so got any ideas how to fix it?
KaosFaction

Joined: Nov 21 2004
Posts: 866
Post Thu Apr 23, 2009 8:30 am

What sort of pitch is the humming? high/low?
Highland J

Joined: Sep 08 2006
Posts: 1157
Location: ND, Land of the covered wagons and wheat.
Post Thu Apr 23, 2009 8:31 am

its a lower hum just a dull droneing mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm
H-Town

Joined: Dec 10 2008
Posts: 1186
Location: Houston, TX
Post Thu Apr 23, 2009 8:37 am

feedback?
DJTricky

Joined: Nov 13 2007
Posts: 880
Location: Robbinsdale, MN
Post Thu Apr 23, 2009 8:42 am

could it maybe be interference do you know if the power/ground and RCA’s are run together or in close proximity.
KaosFaction

Joined: Nov 21 2004
Posts: 866
Post Thu Apr 23, 2009 8:45 am

Can you do a few diagnostic things for me please?

So you are 100% sure that it only occurs when you are parked/stopped? Its not just being deafened by road noise?

Unhook the RCAs to the amp (specifically from the HU side, yea I know a *****), but leave everything else connected so that the amp will turn on and receiver power but just won’t receive a signal. If the humming still occurs, you have a bad ground loop….and in a car that’s fairly odd to have from past experience. The *correct* way to fix this is to try and get things that you are grounding in your car to be grounded at one contact point (or less contact points then you are currently using). I think they also have things that eliminate ground loops for you called GLIs Ground Loop Isolators, just make sure you get one for 12V use of course. icon_biggrin.gif

This in all likely hood is your problem, if you are getting humming when ONLY connected to a powered signal, then there might be an issue with the HU, but one thing at a time.

byte

Joined: Mar 25 2009
Posts: 313
Post Thu Apr 23, 2009 11:47 am

If it is the deck, then it should be hum with the car running or not running…

Does it hum when the engine is stopped? Bad (or wrong type) spark plugs and wires can give off noise.

Highland J

Joined: Sep 08 2006
Posts: 1157
Location: ND, Land of the covered wagons and wheat.
Post Tue May 19, 2009 7:21 am

^^ yea as long as its all turned on there is still a hum, and yes it does when the car is driving too it just gets quieter when i start moving…
JSewell

Joined: Mar 22 2009
Posts: 464
Location: Texas Raised
Post Tue May 19, 2009 7:25 am

as DJ said, check to make sure that the power and RCA cables aren’t close

preferably the power wire on one side, then the RCA’s directly on the other side

silentalero

Joined: Feb 12 2003
Posts: 1047
Post Fri May 22, 2009 11:49 pm

run a separate RCA cable, it most likely just bad rca’s.

test it by removing your radio and runa separate set without tucking the wires anywhere obviously and see if that does it. I doubt its the head unit that would put the hum out. And it doesnt sound like engine whine so i doubt its the rca’s ran next to power either. But just for fyi, make sure the rca’s are ran on the passenger side.

ViciousBread

Joined: Aug 31 2008
Posts: 887
Location: G-String Town Arizona
Post Sun May 24, 2009 12:47 am

he probably ran your power/rca together. Was the problem in my friends sunfire.