XGIMI Horizon Ultra + Sonos Arc Ultra: Dolby Atmos stuttering with 30 m AOC HDMI cable
The idea was to create a home cinema with a decent projector and decent sound, including Dolby Atmos.
The projector is an XGIMI Horizon Ultra, and for the sound system I have two Sonos Era 100s and a Sonos Arc Ultra.
The difficulty with this setup is connecting the projector and the Arc without having a visible cable running across the room. The projector is on the back wall, while the Arc is on the opposite side of the room. The only way to hide the cable is to run it through a lowered ceiling and the technical room.
I estimated the required cable length to be around 19 meters. To be safe, I decided to order a 30-meter HDMI AOC (Active Optical Cable) that is eARC-certified. Since the cable is optical, I assumed the additional 10 meters wouldn't be an issue.
However, before installing the cable behind the wall/ceiling, I tested it in my living room. To my surprise, the sound constantly stutters.
Things I have tried:
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Fully unwound the cable.
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Connected the source end to the projector (HDMI 2/eARC) and the display end to the Sonos Arc Ultra (the Arc only has one HDMI port).
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Switched the ends of the cable around, but this made no difference.
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Bought an HDMI power injector and tried it on both ends of the cable.
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Set the projector's HDMI/eARC settings to eARC and Passthrough.
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Bought an identical second cable and tested that one as well.
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Tested different sources, including Prime with a movie that supports Dolby Atmos.
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I reset the handshake multiple times
To make sure I wasn't going crazy, I then put the projector and Arc on the floor and connected them using the HDMI cable supplied by Sonos. Everything worked perfectly.
I also checked the Sonos app, which confirmed that the audio signal was Dolby Atmos.
So I know that the projector can successfully send a Dolby Atmos signal to the Arc Ultra. It works perfectly with the short copper HDMI cable, but not with the 30-meter AOC HDMI cable.
Has anyone encountered a similar problem with a long active optical HDMI cable and eARC/Dolby Atmos? If so, how did you solve it?
I'm particularly wondering whether this could be related to the 30-meter cable length, eARC bandwidth/handshake, power delivery, or some compatibility issue between the XGIMI and Sonos.
