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Need help with Sub humming VERY loud when I turn off my stereo....

Car Audio, Video, & GPS

Car Audio, Video, & GPS
Talk about stereos, navigation, amps, subs, and all things car audio

Need help with Sub humming VERY loud when I turn off my stereo....

  • Ok, I can't seem to figure out the problem...  I just recently installed a JL Audio 1000/1 amp to a JL Audio 13.5" W7 sub to my '06 Cherokee.  I'm using my factory radio (had to use an adapter to connect the amp) and a capacitor.  When my stereo is on, the sub sounds great, even when I turn the volume all the way down to zero, it is silent.  In addition, when I turn my car off, the amp will turn off & my stereo will continue to say on until I open a door (which is normal for my car), and the sub is silent.  Now if I turn off my stereo manually while my car is running, the amp will turn off & the sub will faintly/slowly hum and eventually VERY loud to wear my ears hurt.  So to avoid this, I just don't turn off my stereo and just turn the volume down when I need to....  Any ideas?

  • Jesse:
    So to avoid this, I just don't turn off my stereo and just turn the volume down when I need to....  Any ideas?

    That sounds like it should work - so what is the problem?  (j/k).

    That sounds like a ground loop issue of some kind, but it seems really odd that it gradually gets louder.  I would try checking and or/relocating the amp ground.

    Does anyone else have a suggestion? 

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • What and where is your amp grounded?

    How is the power supplied to the amp?

    And also, where is your remote wire comming from?

    (2) 5.25" Polk Audio db5251 Components (2) 6" x 8" Polk Audio db571 (2) 1" Polk dB1000 Tweeters (2) 12" JL Audio W6V2 Pioneer DEH-P980BT Head Unit 30 GB iPod Infinity 7541a 4 Channel Hifonics BXi 1206D Super D Class 0 Gauge Knu Konceptz wire
  • Normally, the amp should turn off whenever the HU does... unless you are using your factory HU.

    Never mind, just saw that in your post. It sounds to me like the amp needs to be re grounded. Make sure you scrape all the paint off, and fasten it tightly.

    It might also have something to do with how the remote lead is hooked up.

    2005 Toyota Tacoma Access Cab Alpine CDA-9886 Head Unit Rockford Fosgate 550X amplifier Sundown Audio SAE-1000D Temp - Kicker Solo Baric L5 Temp - Kenwood Coaxials Soon - Fi Q 18, Hertz HSK 165, 120sq.ft. of Damplifier and Overkill
  • Okay, I am going out on a limb here, so someone else suggest something if I seem way off here.

    Amp would be similar to this one. By "use an adapter", I assume you mean a LOC, although you could have used the speaker level inputs (might try that to fix the problem).  I am also assuming you wired the amp remote to something on the fuse block that is only powered when the car is running and also that you are going by sound rather than the amp power lights to say whether the amp is on or not.

    Jesse:
    When my stereo is on, the sub sounds great, even when I turn the volume all the way down to zero, it is silent.

    Makes sense - amp and HU are both getting power.  Amp is getting signal through the LOC and sending it on, however with volume down to zero, not much signal and not much gets amplified. 

    In addition, when I turn my car off, the amp will turn off & my stereo will continue to say on until I open a door (which is normal for my car), and the sub is silent.

    Also makes sense - Amp remote is not getting power, so amp is turned off.  Amp is getting signal through the LOC, but since the remote wire is dead and the amp is unpowered, nothing is amplified and you get silence. 

    Now if I turn off my stereo manually while my car is running, the amp will turn off & the sub will faintly/slowly hum and eventually VERY loud to wear my ears hurt.  So to avoid this, I just don't turn off my stereo and just turn the volume down when I need to....  Any ideas?

    This doesn't make sense (unless the amp has some type of smart sense circuitry where it doesn't need a remote wire and turns on when it senses power on the speaker inputs).  Otherwise, the amp should still be on, but not playing anything - please check whether the power lights are on at the amp when the car is running and the stereo is off - I think they will be on.

    Now with this - what I think is happening is the amp is on, but the stereo is not outputting anything, so the amp should not be playing anything.  However, if you have power wires running past your RCA's, they can pick up this noise and feed it to the amp, causing the hum that you describe.  The speaker level wiring is much less likely to pick up this noise, so I would try using those instead of the LOC, or if you keep the LOC, you might try adding a Ground Loop Isolator.

    (Or never turn the stereo off with the car running, which is pretty much what I do anyway).

    Anyone else have any ideas on this? 

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • Thats definitely possible. If there are any power cables running parallel to the RCA signal cables, then that could be causing the problem.

    I was also thinking that the LOC could be holding some kind of electrical charge, even though the HU is off. Unlikely, but maybe its possible.

    If the amp has high level input, I would try that and see if it fixes the problem. 

    2005 Toyota Tacoma Access Cab Alpine CDA-9886 Head Unit Rockford Fosgate 550X amplifier Sundown Audio SAE-1000D Temp - Kicker Solo Baric L5 Temp - Kenwood Coaxials Soon - Fi Q 18, Hertz HSK 165, 120sq.ft. of Damplifier and Overkill
  • I know this is a bit old but im experiencing the same problem. 

    Jesse Im not sure if youre still around but Id really appreciate if you'd possibly update this with what resolution you came up with... if you didHmm



    [edited by: Nospheratu at 1:31 AM (GMT -5) on Tue, Feb 24 2009]
  • I have the same problem and a fix!

    The problem is that your factory head unit does not have a remote on wire so that means your amp stays on when your radio is off. Now this is where the hum comes in: the hum starts faint then if you roll down a window and back up (anything that uses electricity in your car) the hum should grow very loud. See when you use electricity in your car a frequency is made and that frequency travels through wires which then travel to your amp which is still on and makes a hum because it is not getting any input from your pre amp wires so it reproduces this frequency instead because it is still powering its internal components and outputting static/snow to the subwoofer (kind of like when you unplug the cable from your tv all of a sudden snow and static sound shows up same for the sub when no input audio is supplied).

     The fix: Either buy a new head unit (a.k.a. deck) which has a remote wire for your amp. OR Wire your amps remote wire (usually blue or blue/white) to the ignition wire (colors vary) going to the back of your head unit. Then split the remote wire between the head unit and the amp and connect the wires to an off/on switch so that you can turn your amp off when your radio is off...this switch is also useful if you have someone in the car that does not like bass well you turn the switch off and it will instantly turn off your amp with no hum.

    If you need wire colors such as the ignition wire color or speaker wire color go to http://www.installdr.com/ or http://www.modifiedlife.com/car-stereo-wiring-diagrams-and-car-radio-wiring-diagrams/ or use the information provided by Crutchfield when you buy new headunits, wireing harnesses, and speakers and such.

    Thanks,

    smgtech

     



    [edited by: smgtech at 12:04 AM (GMT -5) on Wed, Apr 08 2009] [edited by: smgtech at 12:02 AM (GMT -5) on Wed, Apr 08 2009]
  • Great post - smgtech!!!

    smgtech:
    If you need wire colors such as the ignition wire color or speaker wire color go to http://www.installdr.com/ or http://www.modifiedlife.com/car-stereo-wiring-diagrams-and-car-radio-wiring-diagrams/ or use the information provided by Crutchfield when you buy new headunits, wireing harnesses, and speakers and such.

    Or go here!!!

    Hope This Helps!!!

    2002 Ford Focus JVC KD-A815 Sony CDX-GT410u Sony XT-100HD HD Tuner Stock speakers, no amp, no subs

  • This is an old post, but this may help those with this problem who find this in a search:

    Even though some of those techniques may partially work, if you turn off the radio while the amp is still powered, the noise will return.

    You need to put a ground loop isolator into the RCA cables and this will solve the issue.