Could this be a setting on your TV or the Apple TV?

I’m having the exact same issue (although your pop sounds louder than mine) and using the exact same setup as you (Apple TV 4K, LG C1, same setup, but have actually tried this with like, 8 different HDMI cords at this point, just to prove I wasn’t crazy!).

I’m about to call Sonos support since their chat wasn’t able to rectify it; about ready to bring it back to the store and swap for a new one. Only other thing I can think of is this is an LG C1 issue, because I had none of these issues when I had the original Arc.

I have this pop happen randomly as well, various content, streaming services, using ATV 4K. I would rewind back to the place of the pop and it wouldn’t happen so it’s not the source directly affecting sound.

The pop sounds like a digital artifact or a compression glitch, louder than all content but louder by a percentage of the set volume. For example, at 50% volume the pop is significantly louder than if the volume is at 30%. So the pop is not 100% each time.

LG CX, ATV 4K, Ultra, 300s, Sub gen 3.

Coming from https://www.reddit.com/r/sonos/comments/1hn98vj/occasional_sparkpopping_sounds_after_upgrading_to/

I’m also getting this on the LG TV, but instead of the CX, it’s the 86NANO75SQA with the Nvidia Shield as source.

TV audio settings: Match Screen and Sound Bypass, Digital Sound Output Pass Through, eARC Support On, DTV Audio Setting Auto, HDMI Input Audio Format All on Bitstream.

I’ve opened a case with Sonos via Live Chat and followed up with a phone call, they have last requested the following information

1. Latest Sonos app diagnostics capture
2. Video + timestamp (+ link if possible) I heard the spark sound when capturing the diagnostics.
3. TV model
4. Active Source
5. Other HDMI devices
6. TV audio settings

So far it’s only a promise to be added to the initial update group if a fix eventually gets rolled out. I’ve just sent the information over the weekend, I’ll do another call to follow-up again soon.

I have noticed that the issue doesn’t seem to occur on Dolby Atmos tracks (it happens on standard surround and stereo) and seems to happen more often when the volume is low.

Someone from the Sonos Customer Escalation Engineering team followed up and asked to schedule a call with a level 3 engineer to get an audio capture from our Arc Ultra. 

We would like to schedule a call with you to get an audio capture from your Arc Ultra. For us to get the audio capture we will need a computer on site that we can remotely connect to and transfer the audio file from.

I’m not sure exactly what this means. Is it normal for them to ask for this? 

Not unheard of, not something I’d be overly worried about, either. Good evidence, at least in my mind, that they are taking the issue seriously, but are not necessarily able to recreate the issue locally, but that’s supposition. 

I had a call with a level 3 engineer from Sonos today who was able to capture the issue during our session so hopefully they will be able to get a fix out

So, what's the resolution? I have continual POPPING sounds with ALL of my streaming services. But not with my cable box. It happened suddenly after flawless sound for months. It makes Sonos unlistenable. 

I have the same issue. And it seems to be getting more frequent. Does anyone have a solution that works?  Does the arc ultra need to be replaced?  Is it software related?  It’s really annoying. 

Yeah I'm still having the same issue, I found out when playing Split Fiction with surround sound enabled in Moonlight on Nvidia Shield and 7.1 showing in my Sonos App would have some scenes trigger the pop sound from my ERA 300 rears as well. But not deterministic, it doesn't happen again when loading from the same part.

My Sonos Setup: LG 55” C1 OLED TV, Bit Stream input, Passthrough output, eARC, Sonos supplied HDMI cable. No speech enhancement enabled. Sonos Arc Ultra, 2 ERA 300 surround speakers, Sub Gen 3 and Sub 4.  

After trying many different options, I have found a permanent fix that has been working perfectly for me over the last five days and about 20 hours of TV usage.  Hopefully this easy fix works for others as well.  Here is my fix:

(1) Disconnect Sonos HDMI cable at Arc Ultra end and then firmly reconnect to Arc Ultra. 

(2) Disconnect Sonos HDMI cable at TV end (eARC HDMI Input) and then firmly reconnect to TV.

(3) Remove Arc Ultra power cable for 30 seconds and then reconnect and let Arc Ultra completely reboot.  You may also want to disconnect power cable from your TV, but I did not need to do that.  Use your TV and Arc Ultra and enjoy!

Good luck to everyone and I hope this easy fix works for others.  I’ll repost here if my clicking/popping sound reoccurs, but hopefully my problem is now fixed! 

I tried your tips, unfortunately it didn't help.

I've been supporting their engineering team in investigating this issue recently.

The latest update:

Thank you very much for sending over the diagnostics and audio tap recordings, we really appreciate your help!

Using the previously collected data, our engineering team was able to identify the issue and is currently working on a solution. For now, no further diagnostics or audio taps are needed.

I’ll keep you updated as soon as I see any progress on the internal ticket. At this moment, there is no estimated time of resolution, but I’ll let you know as soon as I have more information.

Hopefully I hear good news soon!

It would be nice if Sonos would make an official statement on this. This whole thing is really annoying, and I've already tried replacing the hardware once without success.

Same issue here, it’s really infuriating

Calling support is essential in getting issues prioritized for fixing, forum staff seeing posts and flagging them doesn't generate the needed data or urgency a call does.

Any updates to this issue? I just set up an Arc Ultra two weeks ago, latest firware, same settings as OP (also on an LG and Apple TV 4k). The pop ocurrs a couple time per day. Not terrible, but terribly annoying.

As above, if you want a fix on the high priority list CALL, nothing else will have as much impact.

Second option, after calling, might be to try to get i the Reddit Office-Hours discussion and hope enoughothers join to get you an official response.

I tend to agree and that’s the plan. A few comments up, jarylc mentioned Sonos acknowledgement of the issue and a solution was being developed. Just hoping for an update.

I will certainly bump the urgency by calling and logging a ticket.

Support has been useless for me…

If they ask me again to unplug and replug the Arc Ultra and then if it fixed the random issue right away I am going to lose my sanity,..