RFI Radio Frequency Interference

  • 21 January 2022
  • 9 replies

I am an amateur radio operator and when I operate on frequencies 4 mHz or below, my arc sounds the Alexa beep and the surround speakers make rapid drumming sounds (this is with the system off).  When the system is on, the volume will increase to maximum.  This occurs at very low transmitter power (10 watts RF out).  I called Sonos support and after about an hour and talking to two different people, they said they had never had this issue and that it was outside their support.  Any other hams have this issue?  I find no FCC acceptance stickers on the Arc, Sub or Surround speakers.  My transmitter is properly grounded (for RF suppression).  

9 replies

I believe the Arc’s FCC ID is SBV-RM019. Hope that assists.

Thanks, good to know it is registered.  Does not help me solve the RFI issue.


Take care

I’m not sure what you mean by “system off”. Is ARC simply not playing or is ARC powered down? Likewise for the surround’s. Which speakers are you using as surrounds? Are you using any RF suppression in the SONOS power cords? Is ARC wired or wirelessly connecting to your network? If you remove the surround’s from the configuration do you have any issues with the speakers individually or as a Bonded stereo pair?

Do you have issues if the microphone is disabled?

Edit: You are not alone. Try the suggestion at the end of this conversation.

HI, sorry- I get RFI when the Sonos is off, plugged in but not in use.  When watching TV and I transmit, the volume increases to max.  I am using Sonos 1 for surrounds and also have the sub.  I put ferrite cores (mix 31) on the power cords for the ARC and the surrounds.  I am using the ARC on WiFI and I use a Sonos boost.  Removing the surrounds, the RFI still affects the ARC.  Still have issues with the microphone off.  My transmitter is properly grounded (RF) and I have no other devices that are affected. I have ordered more cores and will double them up (stacked) and put more windings around them. 

Thanks very much, I will update as I go along.


If ARC is wired to the network put some beads on the network cable. Fortunately SONOS only uses 100Mbps for the LAN and you don’t need to worry as much about limiting the LAN bandwidth. You could also consider using shielded (and grounded) network cables. Experiment with beads on the HDMI cable between ARC and the TV. Since there is no video you don’t need full bandwidth here. Be anal about neat wire dress and keep everything bundled and as close to the chassis as possible.

Thanks Buzz, continuing to work the problem, I will update


Have a good afternoon

Userlevel 7
Badge +21

A well RF filtered AC power block can help, as can adding ferrite  at the ARC end of the power cord. 

I’ve never had RF issues with my Sonos but have had a lot of them with other audio gear, mostly due to being too close to radio transmitters or the worst radars. In almost every case the RF was coming in over the power leads and aggressively going after them was the solution. One radar was so bad we found using an expandable wire shield (copper version of the ones folks use to pretty up wiring bundles) tied to ground at both ends was needed on some units.

I like the bigger snap-on types and making at least two loops for more blocking.

Something like:  https://smile.amazon.com/RF-Choke-31500-Ferrite-Material/dp/B00XDACVOM/ref=sr_1_30


At one point I was on a military base, testing a just completed tape recorder tune-up. Every few seconds there was a b-u-rrr-p and I was perplexed. Eventually, out of the corner of my eye, I noticed that the noises occurred as a radar antenna swung my way.

Hello All,

I am happy to report success!  I ordered Mix 31 ferrite cores (clamp on and rings) from KF7P Metal Werks.  I used several on the AC cords for the ARC and surround speakers.  I transmitted 500 watts+ with no RFI.  

BTW for Hams, KF7P has a lot of amazing products. 

Thanks for your help and input. And, the XYL is very happy she can watch TV while I use the radio.