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edm
Avid Contributor I
June 19, 2022
Answered

New Arc interfering w/Sennheiser RF headphones?

I have a Sennheiser RS 185 RF wireless headphone system that I have enjoyed for years. As my wife and I are on different sleep schedules, this solution has saved my marriage.

Recently I added a new Sonos Arc, existing subwoofer and 2 Sonos One speakers to my TV. The TV and all Sonos components are working fine. However, except for a couple evenings(out of 2 weeks), I have been unable to get sound from my headphones. I installed and charged new batteries and added a new optical cord, but still no sound. Sonos support said that they cannot help because their components are working, and Sennheiser tells me there must be interference from the new changes that is causing the problem. Can anyone help? After buying the new Arc I can’t afford a divorce lawyer!

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Airgetlam
AirgetlamAnswer
June 19, 2022

It’s not really the Arc, per se, but the fact that CEC only allows a single system to be an audio sink (speakers). 
 

I would suggest turning off ARC (HDMI CEC) on your television, and make sure the optical port is active. 

Bruce
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16 replies

Airgetlam
AirgetlamAnswer
June 19, 2022

It’s not really the Arc, per se, but the fact that CEC only allows a single system to be an audio sink (speakers). 
 

I would suggest turning off ARC (HDMI CEC) on your television, and make sure the optical port is active. 

Bruce
ratty
ratty
June 19, 2022

Assuming the Arc is wireless you’d also want to keep the RS185 transmitter as far away from it as possible. Those headphones use a proprietary wireless in the 2.4GHz band which can interfere with WiFi/SonosNet in the same band. 

    edmAuthor
    Avid Contributor I
    June 19, 2022

    Thanks for the help so far! They are working now but sound keeps cutting out(very briefly) every few seconds. Am somewhat limited with how far I can separate the Sennheiser transmitter from the Arc. If I was certain it would fix the problem permanently, I would hire someone to wall mount tv and Arc. Would that definitely fix the problem?

    ratty
    ratty
    June 20, 2022

    Which sound cuts out? If it's the headphones there's little you can do other than try and reduce the interference they're seeing. They maintain a low latency (delay) by minimising the amount of buffering, making them more susceptible to interruptions. 

      edmAuthor
      Avid Contributor I
      June 20, 2022

      Yes, it’s the headphones that were cutting out, sorry I didn’t make that clear. I moved them as far as I could, which was only a few inches, from the center of the Arc and they actually worked OK for the rest of the evening. Hopefully that was the fix, but it’s been an intermittent issue and I’m not counting on it being permanent.

       

      Does anyone out there know if wall-mounting the Arc(which would increase the distance between Arc and headphone receiver from 15” to 3’) would be a permanent fix?

      ratty
      ratty
      June 20, 2022

      Assuming the Arc is the cause, then any increase in the separation will be welcome. The interference follows the inverse-square law, so doubling the distance reduces the intensity by a factor of four. 

      Presumably the Arc is presently on a TV stand of some kind, or similar furniture. Is it not possible to simply move the RS185 transmitter further away? Optical cables can extend up to 5m if necessary.

        edmAuthor
        Avid Contributor I
        June 24, 2022

        I have moved the Sennheiser transmitter several feet from the Arc- as far as the optical cord allows- but still no sound 90% of the time. 

        edmAuthor
        Avid Contributor I
        June 24, 2022

        It’s not really the Arc, per se, but the fact that CEC only allows a single system to be an audio sink (speakers). 
         

        I would suggest turning off ARC (HDMI CEC) on your television, and make sure the optical port is active. 

        Can you please elaborate, not sure I understand your solution. Are you referring to turning off the eARC port on the tv? That’s where Sonos is connected. Goal is to have sound available from both Sonos and headphones when needed.

        ratty
        ratty
        June 24, 2022

        I have moved the Sennheiser transmitter several feet from the Arc- as far as the optical cord allows- but still no sound 90% of the time. 

        As an experiment, power the Arc off temporarily. See if the headphones start working again. 

          Airgetlam
          Airgetlam
          June 24, 2022

          As @ratty suggests, it’s likely to be the CEC system interfering.

          CEC is explained here.

          Sonos is just one company that uses this standard to do connection between TVs and speakers.

          Unfortunately, CEC has a “one speaker sink” policy, so if you connect a CEC speaker, like the Sonos Arc, to the hub (your TV), and CEC is turned on,  it identifies itself as the only allowable sound device. Depending on how the TV manufacturer has implemented the hub for CEC, it’s possible that turning on CEC and connecting a CEC speaker sink turns off the optical port. It’s rare, I’ll grant you, but it appears to be the case in some TV sets. Turning off CEC on the TV set may or may not turn off the transmission of HDMI ARC that feeds the Sonos Arc, but it would ensure that the optical port is live, which you would be connecting the Sennheiser.

          It’s indeed unfortunate that the CEC standard doesn’t really allow for optional headphones. 

          Bruce
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