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New amp / whining noise when engine running

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  • #16
    Originally posted by bturner2 View Post
    Depending on where the head unit is located there's a short cut that will work as well. If the head unit is located in the glove box and the amps are located under the glove box like most of these boats the quick and easy way is to cut the power and ground to the radio. Splice extensions to the power and ground and route them to the power and ground going into the first amp. Loosen the power cable on the amp and insert the power cable from the head unit between the amp cable and the power cable, then re tighten the clamp. Do the same with the grounds. Since you're pulling power directly from the same source as the amps the connection has to be good.
    Just to confirm: If I take this short cut, I connect the yellow (constant) power cable from head unit to the amp power. The "red" (ignition) I leave as it is?

    Thx

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    • #17
      Yes, leave the switch IGN as is.

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      • #18
        Quick update:
        • I now put dedicated power & ground cables for amp2 (new) and routed to the distribution block (where amp1 is connected)
        • The head unit is connected to the power of amp2 (yellow 12V constant) and ground of amp2 (new).
        • There is an extra ground cable bridging both amps.


        Whining noise reduced a bit, but still noticeable.

        The noise is only there with engine running
        The noise is constant in level (does not change when accelerating and does not change and I turn up the volume). It increases if I increase the gain on the amp itself.

        Any more hints / advice?

        Comment


        • #19
          Originally posted by Lutfu View Post
          Quick update:
          • I now put dedicated power & ground cables for amp2 (new) and routed to the distribution block (where amp1 is connected)
          • The head unit is connected to the power of amp2 (yellow 12V constant) and ground of amp2 (new).
          • There is an extra ground cable bridging both amps.


          Whining noise reduced a bit, but still noticeable.

          The noise is only there with engine running
          The noise is constant in level (does not change when accelerating and does not change and I turn up the volume). It increases if I increase the gain on the amp itself.

          Any more hints / advice?
          Does the whine exist when the RCA's are removed from the AMP?

          D2
          2002 X-Star Indmar 5.7 Vortec Predator (SOLD)
          2010 X-STAR Indmar 6.0
          sigpic

          Comment


          • #20
            More Specifically:

            - Disconnect the RCA's from the amp inputs, and check for the "hum" while the engine is running. If it is still there, than something is grounding into/through your amplifier. Check to see that there isn't anything that its mounted to that is metal, and can be shorting the ground through the chassis of the Amp/Amps. If no hum, move on.
            -Keep the RCA's attached to the AMp, and remove them from the head unit. Is there HUM? check to see that there isn't a power wire in close proximity of the RCA cable as it runs down to the amp. If there is, move it, or get a better shielded cable. If no hum, Move on.
            - When you introduce the Head unit, and the HUM comes back, something is grounding through the head unit. Could be a chassis ground here too, check that there isn't something grounded into the same point as that connector, the frame of the deck, or somewhere in the harness. Maybe something powered in the glovey? 12v Port somewhere near by? Cabin lighting?

            Lots there.. but check back!
            2002 X-Star Indmar 5.7 Vortec Predator (SOLD)
            2010 X-STAR Indmar 6.0
            sigpic

            Comment


            • #21
              Originally posted by D2Dominator View Post
              More Specifically:

              - Disconnect the RCA's from the amp inputs, and check for the "hum" while the engine is running. If it is still there, than something is grounding into/through your amplifier. Check to see that there isn't anything that its mounted to that is metal, and can be shorting the ground through the chassis of the Amp/Amps. If no hum, move on.
              -Keep the RCA's attached to the AMp, and remove them from the head unit. Is there HUM? check to see that there isn't a power wire in close proximity of the RCA cable as it runs down to the amp. If there is, move it, or get a better shielded cable. If no hum, Move on.
              - When you introduce the Head unit, and the HUM comes back, something is grounding through the head unit. Could be a chassis ground here too, check that there isn't something grounded into the same point as that connector, the frame of the deck, or somewhere in the harness. Maybe something powered in the glovey? 12v Port somewhere near by? Cabin lighting?

              Lots there.. but check back!
              Thanks so much for taking your time to reply.

              1) If I unplug the RCA's from the amp2 (new) while engine running the "hum" goes away.
              2) No hum when I disconnect from head unit
              3) I will check this next and post back!

              Comment


              • #22
                Originally posted by Lutfu View Post
                Thanks so much for taking your time to reply.

                1) If I unplug the RCA's from the amp2 (new) while engine running the "hum" goes away.
                2) No hum when I disconnect from head unit
                3) I will check this next and post back!
                You can post a pic of the rear of the bundle as well, maybe there is something there you're not seeing?
                2002 X-Star Indmar 5.7 Vortec Predator (SOLD)
                2010 X-STAR Indmar 6.0
                sigpic

                Comment


                • #23
                  Sounds like wrong type or RCA cable or there is still some voltage differential between the amp and head unit.

                  Are there other RCA output on the back of the head that you move the amp RCA to? Maybe try an LOC and use a pair of speaker output leads.

                  Comment


                  • #24
                    Did you ever get this resolved? I have a similar issue on my boat (tower speaker whine) and am curious if you found the culprit.

                    Not to highjack, but I've noticed mine only do it in the "on" position, and not "accessory" when the boat is in the garage. Interestingly, in the "on" position but not running, it whines initially, and then I hear almost an audible click after several seconds, and then the whine is gone. When running though, it doesn't go away, and is if anything louder.

                    I have verified that the power and ground coming out of the head unit have been cut before the connector to the main harness and re-routed to the amps. Those connections seemed loose, so I made new splices last night and it "seemed" to remove the whine entirely in the garage, in both on and accessory... but will not know for certain until this evening when we take it out and run it whether I actually corrected the problem.

                    One question I had for someone with some know-how, is whether the automated battery switch/isolator could be the culprit? That could explain why accessory is fine (both amps to the same battery, independent of the second battery), but in "on", both batteries become connected to one another when the isolator combines them to start/charge... and then I have the whine..... thoughts?

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                    • #25
                      Hi forum

                      I never managed to resolve this.

                      To re-cap:

                      Whine/hum coming our of speakers only when engine is running
                      Constant pitch / intensity independent of RPMs or volume
                      Whine/hum does not come when I disconnect RCA's from head unit
                      There is a small voltage different between head unit and unplugged RCA cables ground
                      Head unit ground is connected to same ground as AMP

                      Any advice / trouble-shooting highly appreciated!

                      Comment


                      • #26
                        I read through this. To me, sounds like grounding or sensitivity. I am sure you looked into this but:
                        Attached Files

                        Comment


                        • #27
                          Originally posted by Lutfu View Post
                          Hi forum

                          I never managed to resolve this.

                          To re-cap:

                          Whine/hum coming our of speakers only when engine is running
                          Constant pitch / intensity independent of RPMs or volume
                          Whine/hum does not come when I disconnect RCA's from head unit
                          There is a small voltage different between head unit and unplugged RCA cables ground
                          Head unit ground is connected to same ground as AMP

                          Any advice / trouble-shooting highly appreciated!
                          Lutfu,

                          Can you send a picture or diagram of your setup? There is noise being introduced through your headunit's ground or power. This was verified with your RCA test.

                          The head unit itself my be grounded through a strap on the back of the HU to another device nearby; you need to check everything. Typically I would have aground and a power distribution block that would branch off to the AMPs. Running a bridge between the two may help, but its a lot of variables.

                          Do you have anything else in the setup not mentioned? EQ? Bluetooth adapter? How are your remote turn-ons wired? did you check your low/highvoltage setting on the input for the new amp?

                          Whats happening is that you have power that is finding an easier path through the RCA's to the amp than the ground thats provided. This voltage is producing the hum that you hear. If it is not associated with the engine RPM, means that it is a constant voltage... Which may isolate the devices to something thats regulated.

                          Is your Head unit cleanly grounded?
                          Do you have a wire leaking to the RCA lead somewhere?
                          Is sound only leaking into your new AMP?
                          Did you use use a different RCA "zone" from the HU to the new amp?
                          If you switch RCA's from old to new, does the sound travel?

                          These things are annoying, but generally pretty isolated.

                          D2
                          2002 X-Star Indmar 5.7 Vortec Predator (SOLD)
                          2010 X-STAR Indmar 6.0
                          sigpic

                          Comment


                          • #28
                            Awesome site and glad I found this thread. Will keep following. It may hold my solution.

                            I have a Prostar 205 that whines terribly (rpm modulated) when motor is on. Plan to go check grounds as soon as I get back out there.

                            I have two batts from previous owner one for the boats system and one for the amp. I expect to find the amp and head unit grounded to different batts.

                            Hope a simple fix to one common ground gets rid of the annoying whine.

                            Sent from my SM-N986U1 using Tapatalk
                            1998 Prostar 205 (red)

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                            • #29
                              Check the grounds for what? Everyone says says, but no one elaborates what to "check". Post #15 is where id start.

                              Comment


                              • #30
                                OK, managed to finally solve this: The AUX harness connecting the radio to the amps etc. was bad. There must have been small internal damage on one of the wires causing the whining noise. What I am still surprised, this only happened with engine running.
                                Attached Files

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