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Interference from EOP devices

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  • Interference from EOP devices

    A customer's Hartke A100 amp was motorboating. When the amp was relocated from the rear to the front of the house, all was quiet. It turned out that he had Ethernet over Power adaptors plugged into the room next to where the amp was. I have heard that these can cause problems with RF devices such as ham radios, but I haven't experienced audio gear being effected before. I believe his Fender Bassman 200 was affected as well. Does anyone know of any line filters available to eliminate this?

  • #2
    Grab any of those FILTERED outlet strips as used for computers. See if it makes a difference.

    And get an outlet tester to make sure the outlets in the affected part of the house are properly wired.
    Education is what you're left with after you have forgotten what you have learned.

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    • #3
      Originally posted by Enzo View Post
      Grab any of those FILTERED outlet strips as used for computers. See if it makes a difference.

      And get an outlet tester to make sure the outlets in the affected part of the house are properly wired.
      Thanks Enzo, I'll try that. The house is a relatively new build, but I'll check the outlets as well. I'm a qualified Electrician so I have all the gear to test them.

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      • #4
        It certainly has not been proven that the EOP devices are the cause of the amp problems.

        As they operate in the Mhz band, it is hard ti imagine how that could make a linear power supply, Cklass A/B amplifier 'motorboat'.

        http://www.quora.com/In-a-nutshell-h...-adapters-work

        It may actually be a problem in the two amps. (failing smoothing capacitors)

        A more systermatic approach would help prove the cause.

        Aside: if it is a new house, why did they not run Cat5 cable?
        Last edited by Jazz P Bass; 06-19-2015, 01:52 PM.

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        • #5
          Because everything is moving to wireless. Cat5 is so 2010.
          --Jim


          He's like a new set of strings... he just needs to be stretched a bit.

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          • #6
            Originally posted by Enzo View Post
            Grab any of those FILTERED outlet strips as used for computers. See if it makes a difference.

            And get an outlet tester to make sure the outlets in the affected part of the house are properly wired.
            When you gig, you learn that lesson the first time you play a dive where the owner does all his own maintenance and you don't have spit guards on the mic's !! Anyone else here ever been shocked through the lips? I picked up an outlet tester very soon after.
            "Take two placebos, works twice as well." Enzo

            "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

            "If you're not interested in opinions and the experience of others, why even start a thread?
            You can't just expect consent." Helmholtz

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            • #7
              Many years ago, our guitarist lifted his axe up while playing, the high E string touched the microphone and burned in half. BZZZZT.
              Education is what you're left with after you have forgotten what you have learned.

              Comment


              • #8
                Originally posted by Jazz P Bass View Post
                It certainly has not been proven that the EOP devices are the cause of the amp problems.

                As they operate in the Mhz band, it is hard ti imagine how that could make a linear power supply, Cklass A/B amplifier 'motorboat'.

                In a nutshell, how do ethernet over power line adapters work? - Quora

                It may actually be a problem in the two amps. (failing smoothing capacitors)

                A more systermatic approach would help prove the cause.

                Aside: if it is a new house, why did they not run Cat5 cable?
                I would say the house is probably 5 years old. I don't know why Cat 5 wasn't run, probably the developer saving on costs in the estate. I agree that it is not definitive that the EOP's are the issue, but it was uncanny that as soon as the amp was moved to the front of the house the symptoms ceased. I had already taken the amp back to my workshop and disassembled it and found no problems with caps, the supply rails were very stable, minimal ripple and I could not replicate the problem.

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                • #9
                  I would consider a wireless router.

                  That EOP is great for 'home automation'.

                  But I would not want my data on a 120Vac power line.

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                  • #10
                    Originally posted by Jazz P Bass View Post
                    I would consider a wireless router.

                    That EOP is great for 'home automation'.

                    But I would not want my data on a 120Vac power line.
                    What makes it scarier is it's on 240vac. The house is few years old and was not wired for Cat5 when built. I don't know why the owners have gone for EOP

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                    • #11
                      EOP is nifty and neat solution - I use it to put another wireless router up the other end of the house.

                      Was there anything plugged in to the amp when it was motorboating - eg. guitar lead, effects leads? If not, then was the motorboating related to some part of the amp (eg. before the vol or tone)?

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                      • #12
                        There was nothing plugged into the amp. Adjusting tone controls made no difference to the motorboating.

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                        • #13
                          I guess the other diagnostic would be if you were able to unplug the EOP devices at the time of the motor-boating to provide a higher confidence of directly correlating EOF with the motorboating.

                          It certainly is an interesting example of what may be external interference.

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                          • #14
                            Originally posted by gui_tarzan View Post
                            Because everything is moving to wireless. Cat5 is so 2010.
                            Yeah! Twisted pair is so old-school. My house is all Cat5 wired, so it's hard to get a connection, have to plug into a wall outlet. Sometimes it's easier just to select one of the three neighbor's wifi's that I can pick up and use... and watch their traffic... etc.
                            Amazing!! Who would ever have guessed that someone who villified the evil rich people would begin happily accepting their millions in speaking fees!

                            Oh, wait! That sounds familiar, somehow.

                            Comment


                            • #15
                              Originally posted by R.G. View Post
                              Yeah! Twisted pair is so old-school. My house is all Cat5 wired, so it's hard to get a connection, have to plug into a wall outlet. Sometimes it's easier just to select one of the three neighbor's wifi's that I can pick up and use... and watch their traffic... etc.
                              Yeah, for a desktop setup I would go cat5.

                              Laptops, fegetaboutit.

                              Quote" Sometimes it's easier just to select one of the three neighbor's wifi's that I can pick up and use."

                              Your neighbors don't use security settings?

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