1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

S6 "engine Noise" after amp install

Discussion in 'In-Car Entertainment' started by enda1, Oct 2, 2009.

  1. enda1
    Offline

    enda1 Member

    Joined:
    Jan 17, 2006
    Messages:
    436
    Likes Received:
    0
    Folks.

    I just finished installing new kit as below in my 96 Audi S6.
    I am running this with my exisitng Sony head unit with 4 channels out , 2 Front and 2 rear
    Amp JBL GTO 540
    Front Components 5.25 JBL P560C
    Rear 6x9 JBL P963
    Wiring kit FLI Audio AK10 10AWG.
    New speaker cable.

    I wired the +ve to the battery (under the rear seat) and the -ve to the chassis mount of the ABS unit (under the rear seat)

    With the ignition off the sound is great but with the engine running I get a speed related whining noise through all the speakers.

    Did a bit of checking and will try the following.
    Get a better earth point
    Reroute the power cables away from the RCA signal cables.

    If this doesn't work can someone suggest a suitable noise suppressor to fit in line with the positive cable to get rid of this interference
    Last edited: Oct 2, 2009
    #1
  2. Broken Byzan
    Offline

    Broken Byzan Photographic Moderator Staff Member Moderator

    Joined:
    Apr 26, 2004
    Messages:
    12,568
    Likes Received:
    9
    Change the earth, it is very unlikely interference is causing it.

    You didnt power the amp up with no RCAs connected and then plug them in did you? That can blow earth tracks in the HU causing all sorts of issues.

    I would say though 95% earth problem
    #2
  3. alijames
    Offline

    alijames Active Member

    Joined:
    Feb 10, 2008
    Messages:
    1,024
    Likes Received:
    0
    I had the same problem when I replaced the Bose amp in my S3 with an Alpine 5 channel, even with the earth connected directly back to the Battery, so that was not the problem.

    My solution was to install ground loop isolating transformers into the RCA connections.

    I got mine from a local Car Audio place, but Maplin do some :

    http://www.maplin.co.uk/Free_UK_Delivery/Ground_Loop_Isolator_33172/Ground_Loop_Isolator_33172.htm

    They are not the smallest bits of kit, but work well for me...

    Cheers,
    #3
  4. enda1
    Offline

    enda1 Member

    Joined:
    Jan 17, 2006
    Messages:
    436
    Likes Received:
    0
    Bryzan I conneted the the RCA and powered up last of all so this shouldn't be the problem, also the sound is crystal clear with the engine off.

    Alijames. if nothing else works i'll give these a try. I assume you install at the amp end of the RCA and not the head unit end
    #4
  5. AndyMac
    Offline

    AndyMac Moderator Staff Member Moderator

    Joined:
    Jun 10, 2003
    Messages:
    9,833
    Likes Received:
    7
    If the earth is not the issue then I'd upgrade the RCA's. You don't say what RCA's you are using but there are some pretty badly screened ones out there. Also what earth have you used at the HU. If it's just the stock earth from the Audi loom then I'd add a proper chunky one from the chassis to the chasis of the HU as the Audi one is pretty poor. Don't bother running the RCA's away from the power as this is very unlikely to be the problem.
    #5
  6. enda1
    Offline

    enda1 Member

    Joined:
    Jan 17, 2006
    Messages:
    436
    Likes Received:
    0
    The RCA's are the ones that came with the FLI wiring kit. I am using the stock earth at the head unit so I will look at changing this as well.
    #6
  7. AndyMac
    Offline

    AndyMac Moderator Staff Member Moderator

    Joined:
    Jun 10, 2003
    Messages:
    9,833
    Likes Received:
    7
    Right, so they are probably garbage, but start with the earths.
    #7
  8. enda1
    Offline

    enda1 Member

    Joined:
    Jan 17, 2006
    Messages:
    436
    Likes Received:
    0
    I tried a better earth for the amp and it was no better. I didn't have time this weekend to take the centre console of to run a better earth for the head unit so I treid the ground loop isolators alijames suggested and it solved the problem without any discernible change to the sound quality so I'll stick with them until I get the time to earth the head units
    #8

Share This Page