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  1. #1
    Join Date
    Jul 2011
    Location
    Murrieta, CA
    Posts
    1,007

    Default Electrical whine

    Any advice on why I have a new electrical whine from my sub amp?

    The problem just started and I have not modified the system. The whine happens with the engine running and when the fuel pump primes at key on.

    Whine disappears when RCA cable is unplugged from eq or amp. I also tried a jumper RCA from the eq to the amp and the noise was still there.

    Any suggestions on where to start?

    Thanks!
    2010 Moomba XLV
    340hp cat
    Gravity 3, wake plate
    Rad-a-cage

    I have a love for ballast and large wakes.
    1100 v-drive lockers
    1180 under the playpen
    + lead and a collection of other ballast bags

  2. #2
    Join Date
    Oct 2010
    Location
    Lake Wylie NC Area
    Posts
    786

    Default

    Give us some additional details about the system. Try running RCA direct from head-unit to sub amp.

  3. #3

    Default

    That's unusual that you would have a pronounced whine on the subwoofer amplifier that you do not have on the fullrange or highpass channels of other amplifiers since the sub amplifier lowpass filter would normally mute the high frequency whine. A 'hum' would be more typical on the sub.
    One initial step is to short the sub amplifer's RCA inputs and check for the noise. If the noise remains you know that it is an issue either within the amplifier or in the sub wire. All it takes is one tiny shorted strand. If the noise is eliminated then you know the culprit is upstream in a component or a component to component relationship issue or a grounding issue.
    Then triple check the quality of the sub amplifier's primary ground. Also, check the ground quality of both batteries.
    Check for good battery voltages and check 'ALL' audio components get power from the identical physical point and identical ground point. No exceptions.
    Make sure the RCA cables are well seated.
    Whether a HU or EQ is feeding the amplifiers, measure the resistance between the unplugged RCA ground shield and the true primary ground to make certain that all RCAs show the consistent value.

  4. #4
    Join Date
    Jul 2011
    Location
    Murrieta, CA
    Posts
    1,007

    Default Electrical whine

    I am rerunning my power wires to clean up the original install mess. I just added and added without keeping the install as clean as I would like.

    I have a battery selector switch (1, 2, 1+2, off). Should my stereo power wire be connected direct to battery 2 + post or connected to the common post on the battery selector switch?

    I have all stereo grounds to battery 2 - post.
    2010 Moomba XLV
    340hp cat
    Gravity 3, wake plate
    Rad-a-cage

    I have a love for ballast and large wakes.
    1100 v-drive lockers
    1180 under the playpen
    + lead and a collection of other ballast bags

  5. #5

    Default

    If you want to avoid all future B+ supply conflicts and make the use of the selector switch more unconscious, as it should be, then everything (100% of the audio components, the helm buss, and the starter/alternator feed) should be connected to the common/output post of the battery switch. And nothing should be wired battery-direct except for the switch #1 & #2 terminals and possibly the bilge pump & float switch if you moor the boat.

  6. #6
    Join Date
    Jul 2011
    Location
    Murrieta, CA
    Posts
    1,007

    Default Electrical whine

    Ok - thanks David!

    Not sure what the change is but now I have a whine from the cabin speaker amp with fuel pump running. Whine goes away when I unplug RCAs from cabin amp. Whine is present when I use a different RCA cable from the EQ to the cabin amp amp.
    2010 Moomba XLV
    340hp cat
    Gravity 3, wake plate
    Rad-a-cage

    I have a love for ballast and large wakes.
    1100 v-drive lockers
    1180 under the playpen
    + lead and a collection of other ballast bags

  7. #7
    Join Date
    Jul 2011
    Location
    Murrieta, CA
    Posts
    1,007

    Default Electrical whine

    Quote Originally Posted by MLA View Post
    Give us some additional details about the system. Try running RCA direct from head-unit to sub amp.
    I'll try this when Amazon delivers all the new wiring components. I decided to rework my tangled mess of wiring. System is torn apart for a couple of days.
    2010 Moomba XLV
    340hp cat
    Gravity 3, wake plate
    Rad-a-cage

    I have a love for ballast and large wakes.
    1100 v-drive lockers
    1180 under the playpen
    + lead and a collection of other ballast bags

  8. #8
    Join Date
    Jul 2013
    Location
    Windsor ON
    Posts
    80

    Default Electrical whine

    Interested to find out the problem. Keep us posted.

  9. #9
    Join Date
    Jul 2011
    Location
    Murrieta, CA
    Posts
    1,007

    Default Electrical whine

    I never use my headunit as an audio source but I use the headunit remote turn on lead to turn on the amps. The headunit is still on the factory wiring circuit. Can the remote wire/headunit being ground and accessing power through a different path than the amps cause issues?

    Thinking of wiring the headunit remote wire to a relay to turn on the amps. I would wire the power and ground for the relay to the same power and ground sources for the amps. My thinking is this would provide "clean" power for the remote turn on at the amps.

    Would this work or should I do something different? I have no plans to use the headunit as an audio source. I just want the easiest path to use the dash stereo switch to turn on/off the stereo.

    Thanks again for all the advice.
    2010 Moomba XLV
    340hp cat
    Gravity 3, wake plate
    Rad-a-cage

    I have a love for ballast and large wakes.
    1100 v-drive lockers
    1180 under the playpen
    + lead and a collection of other ballast bags

  10. #10
    Join Date
    Oct 2010
    Location
    Lake Wylie NC Area
    Posts
    786

    Default

    Boon,

    You easily bypass the head-unit and trigger the amps on directly. Use the red switched 12 that triggers the head-unit now, to trigger your relay that would supply the 12v trigger to the amps. Since that amp turn-on circuit is not in the signal path, where that 12v comes from, is not as crucial as the actual head-unit/EQ constant B+.

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