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Audio not syncing

I bought a brand new AppleTV 4K 2 days ago. Set it up with my Denon receiver and 4K TV using Dolbyvision 4k as video and turned matching off as people have recommended that. Everything worked great for 2 days. Today audio syncing is out of whack, which is ridiculously annoying. It doesn’t sync on any show, whether AppleTV+, Disney+ or Netflix. I restarted the AppleTV. No change. I changed video settings all the way down to 1080p HD. Restarted. No change. I changed settings to 720p. No change. My AppleTV is hard wired with cat5 Ethernet cable to 1Gb fiber Internet. I have a new high end 8k HDMI cable. What gives? What’s the secret to getting audio to sync consistently?

Apple TV 4K, tvOS 15

Posted on Oct 9, 2021 9:01 PM

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Question marked as Top-ranking reply

Posted on Oct 14, 2021 6:54 PM

I had to spend a few days testing a theory and it turned out to be the cause of the issue. It's actually something that possibly affects all AppleTVs.


The top of my Denon receiver gets pretty hot. It's uncomfortable to touch, possibly around 120 degrees F. I had the new AppleTV box sitting on top of the receiver, not thinking about how the heat might affect it. Realizing this might be an issue, I moved the AppleTV box to the side of the receiver. A short time later the audio syncing started working perfectly.


So I thought it was worth another test. I took a different AppleTV box (it's a 4K model I use in another room, but not the latest gen) and placed it on top of the Denon and left it there for a few days. After about 2 days it also started developing the same audio sync issues.


I suspect that the fine tolerances on modern chip components are exceptionally sensitive to heat, as it can expand metal elements just enough to cause problems like these. Add to that the closed environment of the AppleTV and the compact nature of the unit itself, and you have a perfect environment for this kind of problem.

3 replies
Question marked as Top-ranking reply

Oct 14, 2021 6:54 PM in response to barberlives123

I had to spend a few days testing a theory and it turned out to be the cause of the issue. It's actually something that possibly affects all AppleTVs.


The top of my Denon receiver gets pretty hot. It's uncomfortable to touch, possibly around 120 degrees F. I had the new AppleTV box sitting on top of the receiver, not thinking about how the heat might affect it. Realizing this might be an issue, I moved the AppleTV box to the side of the receiver. A short time later the audio syncing started working perfectly.


So I thought it was worth another test. I took a different AppleTV box (it's a 4K model I use in another room, but not the latest gen) and placed it on top of the Denon and left it there for a few days. After about 2 days it also started developing the same audio sync issues.


I suspect that the fine tolerances on modern chip components are exceptionally sensitive to heat, as it can expand metal elements just enough to cause problems like these. Add to that the closed environment of the AppleTV and the compact nature of the unit itself, and you have a perfect environment for this kind of problem.

Audio not syncing

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