Hum noise

Hi Ya All,
Happy Friday and very happy (I hope) weekend. Forgive me if this has topic been here for a few times. I tried to find answer by going through the previous posts, but could not get clear understanding. So thought to post.

I have been noticing an annoying hum noise in my HT system. The processor is Marantz AV7702MKii. All sources are connected to the processor including cable box, roku and blue ray player. The power supply is through Belkin power conditioner to which power plug of two amps are connected as well.

The humming noise was really annoying. So I started to take off the sources one after another in order to understand where it is coming from. Unplugging them did not help. Then I started to disconnect the HDMI cables, one source at a time. And the cable between the cable box and processor did the trick. This HDMI cable is not what the cable company provided, but it is a bluejeans cable. The same type of cable is also connected between roku and the marantz processor, but I do not see any humming issue from roku.

So, what can I do to solve the cable box hum. One option is to disconnect at times when I am not watching the cable. But that is kinda pain in the rear.

Any suggestions??- I was thinking to try another HDMI cable and see what happens.


  • kharp1kharp1 Posts: 3,463
    I've seen where the cable box has been the culprit in several hum cases.
  • mpitogompitogo Posts: 446
    edited June 2018
    Does the Marantz pre have a 3-pin IEC connector with ground? If not it may be a floating ground. Cable companies always (typically) grounds their coax to earth and you likely have a ground loop. You can look it up but basically there is a difference in potential between the two components’ ground. Try connecting the cable box ground if one exists or a chassis screw to the receivers ground if a phono input exists. All of the components should reference the same ground. The cable box is carrying earth ground on the shielding bringing it into the box and the box may only have a two pin power connector.

    Does the Belkin power conditioner have a grounding screw? You can reference this for all components with a chassis ground if they don’t use a standard IEC 3-pin C13-C14 to 5-15 power cable.
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  • kharp1kharp1 Posts: 3,463
    Yep2 wrote: »
    but basically there is a difference in potential between the two components’ ground.
    Every component has a "potential difference".

    There's a difference between "every component have potential differences" and the ground potential difference causing a hum.
  • Mr. SharpeMr. Sharpe Posts: 1,275
    Hey buddy, when I unplug my cable line from the box my Him/buzz will stop, if the wire touches the box it will start. I second the ground loop. Same thing happened at my parents old house and it made me so mad bc I couldn’t listen to music without hearing it.
    Electronics: Westinghouse 43" LED, Marantz UD-7007 player, Denon AVR-x3100w receiver/preamp, DIY Ethereal ESO-1 power conditioner, Parasound HCA-1500a power house.

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  • jumpindickjumpindick Posts: 375
    I agree that it can be so frustrating. Those cable boxes are cheap... I am in the process of getting another one (not sure if that will help) and see if anything changes. If not, I will have to look for another way to stop the humming noise and still use the cable box.
  • nienteniente Posts: 68
    I also had same issue with cable box.
    IMHO Its due to difference in grounds. Amp etc grounded through house wiring.....cable grounded outside house.

    Is your cable box 3 pronged plugged into same circuit?
    Add RF isolator...

    Save$ and get rid of cable! No hum either!

    Good luck
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  • Airplay355Airplay355 Posts: 4,294
    Who is your cable provider?
  • jumpindickjumpindick Posts: 375
    Spectrum, in Florida. I have requested another cable box. I have not had chance to play with the new one yet, as life has been hectic lately. I am also getting a new "better" HDMI cable as well. Although the current HDMI cables are from the same manufacturers (bluejeanscable). The one connected with ROKU is perfect, and no Hum. The problem is with the cable box.

    Let's see how the another cable box will do... I will post my observations.
  • msgmsg Posts: 5,662
    As noted above, it's most likely not the box, but a difference in multiple grounds in your system.
    I disabled signatures.
  • Airplay355Airplay355 Posts: 4,294
    Their boxes are horrible. I ditched the box completely and just use some kind of DVR card as my "equipment" since you've got to rent something from them. I use a Roku and the Spectrum app. No hums, much faster and better interface, and no renting tons of boxes.
  • jumpindickjumpindick Posts: 375
    You know that is a good idea. I did not thought about it. Does it allow to watch live tv or is it strickly on the go, pre-recorded shows? I am gonna dig into this.
  • machonemachone Posts: 1,236
    Hulu live tv is 40 month and includes all the espn channels. I have been trying it this week and plan to cut the cable soon.
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