There is a bug in Sonos’ home theater sound bars wherein mono Dolby Digital 1.0 and DTS 1.0 tracks play back as silence. I’ve experienced it personally on a Gen 1 Beam. A quick Google search shows multiple reports of the problem on these forums as well as on Reddit. I believe the problem persists on the Gen 2 Beam as well.
The bug is easy to reproduce--
- Play back any 1.0 encoded Dolby Digital or DTS source through a normal ARC setup to a Beam or other Sonos soundbar
- Confirm in the Sonos app that the Beam is receiving TV audio and note that app displays the correct flag (e.g. “Dolby Digital 1.0”)
- Note that no sound plays back from the Beam.
A workaround to the problem is to change the TV or BD/DVD Player to output as 2.0 PCM instead of bitstream, but again, this is not a fix so much as an inconvenient workaround, and requires the end user to change the setting back after viewing mono content so that future surround content is handled properly.
Furthermore, I’ve confirmed this is a bug in the Beam itself and *not* a problem with the ARC being processed incorrectly or sent incorrectly via the TV through an additional set of steps--
- While the 1.0 stream is still playing back to the Beam and producing no sound as above, create a group in the Sonos app between the Beam and another Sonos product. In my case, I grouped my Beam with a Move.
- The Dolby Digital 1.0 sound plays back audibly and correctly from the Move while the Beam continues to produce only silence.
These steps demonstrate the bitstream DD or DTS 1.0 track is making it to the Beam intact and due to some bug, the Beam isn’t outputting it. Ironic, as the Beam and its other soundbar cousins are the only Sonos devices that are likely to encounter DD or DTS 1.0 audio in the wild.
Sonos, please address this issue!