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  1. #1
    Join Date
    Jul 2014
    Posts
    4

    Default Terrible Noise While Running

    Hey Guys, First post here. Recently got a Memphis MXA 5.750 installed with 4 memphis 6.5" and a 10" memphis sub. The system sounds great when running off just the battery, however when the engine is running, I get a horrible whine coming from my speakers. I took a video of it and it's on youtube. https://www.youtube.com/watch?v=oP5VXnalziI

    The noise rev's up with engine RPM's. I've got 2 batteries and the ground for the amp is on one battery, with the power coming from the other. I did not do the install, and the guys that did have done hundreds before. The ground for the head unit is going to a distribution block behind my gauges. I'm not real sure where the power is coming from.

    I really have no idea where to start, so any help would be appreciated. The confusing thing to me is that the system works flawlessly when running off just the batteries, but as soon as the engine is cut on, the noise is so bad I can't even hear music.

  2. #2
    Join Date
    Mar 2014
    Location
    Park City, Utah
    Posts
    259

    Default

    First welcome to the Forum, what year and model is your boat?

    I had the same issue with my system. Two batteries, Two amps, head unit etc. Sounded great when engine was turned off, terrible when engine running. Here's what I did.

    Installed both positive and negative distribution blocks. Ran 4 gauge wire from same battery (2) to each block. From the block ran 8 gauge to each amp. Head unit was tied into the boat wiring, only thing there was moved the ground from the head unit to the ground block. Lastly was to make sure source (RCA) cables and power cables to the amps were not touching and had plenty of space between them. After the above, system sounds great.
    2006 Mobius LSV
    2004 Stingray 190LS - Sold
    2013 RAM 2500 Diesel - Tow Rig

  3. #3
    Join Date
    Jul 2014
    Posts
    4

    Default

    It's actually a regal 1900, and I've not had much luck over on that forum, but figured the guys on a wakeboat forum would likely have a good bit of experience troubleshooting electronics. I've just got the one amp, and don't plan to add more. I wouldn't really need to use a distribution block then would I? The way it's installed now for some reason has the ground from the amp going to one battery and the power source coming from the other.

    I'm running 4 gauge all the way up to the amp, so the size wire shouldn't be the problem. How do you recommend:
    1.) Identifying the ground from the head unit and
    2.) Where to run that ground once it's been identified. Because right now it runs from one console to the other on the main ground block for all the gauges and other accessories. Could i hook it into the ground for the amp, or would i need to run a separate wire all the way to the back.

  4. #4
    Join Date
    Jul 2014
    Posts
    4

    Default

    Quote Originally Posted by lakemurray View Post
    I'm running 4 gauge all the way up to the amp, so the size wire shouldn't be the problem. How do you recommend:
    1.) Identifying the ground from the head unit and
    .
    Figured this out...its black

  5. #5
    Join Date
    Mar 2014
    Location
    Park City, Utah
    Posts
    259

    Default

    Quote Originally Posted by lakemurray View Post

    2.) Where to run that ground once it's been identified. Because right now it runs from one console to the other on the main ground block for all the gauges and other accessories. Could i hook it into the ground for the amp, or would i need to run a separate wire all the way to the back.
    I put my head unit ground right into the ground distribution block.
    2006 Mobius LSV
    2004 Stingray 190LS - Sold
    2013 RAM 2500 Diesel - Tow Rig

  6. #6
    Join Date
    Nov 2009
    Location
    Stillwater, Oklahoma
    Posts
    319

    Default

    Quote Originally Posted by lakemurray View Post
    Hey Guys, First post here. Recently got a Memphis MXA 5.750 installed with 4 memphis 6.5" and a 10" memphis sub. The system sounds great when running off just the battery, however when the engine is running, I get a horrible whine coming from my speakers. I took a video of it and it's on youtube. https://www.youtube.com/watch?v=oP5VXnalziI

    The noise rev's up with engine RPM's. I've got 2 batteries and the ground for the amp is on one battery, with the power coming from the other. I did not do the install, and the guys that did have done hundreds before. The ground for the head unit is going to a distribution block behind my gauges. I'm not real sure where the power is coming from.

    I really have no idea where to start, so any help would be appreciated. The confusing thing to me is that the system works flawlessly when running off just the batteries, but as soon as the engine is cut on, the noise is so bad I can't even hear music.
    You probably don't realize it but you diagnosed your problem in all likelihood. The head unit is at a different voltage potential than the amp. See bold part of your post above.

    Move head unit power, (red and yellow wires) and ground, (black wire) to the same place the amp power is coming from, at the battery or even better, terminate the head unit power and ground right at the amp.

    Your head unit red wire needs to go through a switch of some sort. It either needs to go through the accessory circuit of your ignition switch, or if you have a rocker switch for your stereo just use that switch and re-route the switch power from the helm to either the battery or the amplifier.

    If after relocating your head unit power wire you still get that whine check your amplifier gains and make sure they are not too high. In a boat this is probably the second-most common problem of the noise you describe.

    Your problem is a common one, and is easily diagnosed.

    Phil
    Kicker

  7. #7
    Join Date
    Jan 2008
    Location
    Tallahassee, FL
    Posts
    11,389

    Default

    Quote Originally Posted by lakemurray View Post
    It's actually a regal 1900, and I've not had much luck over on that forum, but figured the guys on a wakeboat forum would likely have a good bit of experience troubleshooting electronics.
    Props to you for honesty even though you are a trespasser. These guys will help you anyway and you'll end up buying an SC boat eventually.
    My Mom said I'm not allowed to get wet!
    2008 LSV
    2000 Outback LS (sold)
    Exile Tunes
    PWI
    LLTR!!!!!!!!



  8. #8

    Default

    lakemurray,

    All boats have multiple forms of noise within their DC system. And alternator whine is the most prominent. The difference is that a well-planned & installed system does not permit the noise to enter the signal path. When you have multiple power source points and multiple ground points you are gift-wrapping noise induction. So just like it is outlined above, ALL power for ALL audio components should go to the same physical point and ALL grounds for ALL audio components should go to the same physical point.
    Also, if you have dual batteries and a dual battery switch, in order to avoid other conflicts, it would be better for all electronics positives to access the output of the battery switch rather than going battery-direct.

  9. #9
    Join Date
    Oct 2009
    Location
    Pacific NW USA
    Posts
    513

    Default

    omg trespasser. Chuckles. That cracked me up. Looks like a lot of good feed back already so I won't beat the audio horse. hehe

    -Brian
    Exile

  10. #10
    Join Date
    Jul 2014
    Posts
    4

    Default

    Hey all, switched out the RCA cable when I got home today and reroute it away from the power supply. Totally did the trick. I really appreciate the quick and informative help I got here. Will definitely have to look at moombas when the admiral decides to upgrade the fleet if for nothing else the support here. And a good friend has one and it is badass.

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