Beam Gen 2 Dolby Digital 5.1 vs Atmos Loudness

  • 20 January 2024
  • 1 reply

I’m writing to you after giving up on messing with settings and trying to figure out what is going on with my setup. I am completely puzzled and really need help.

My setup consists of:

- Apple TV 2022 128GB
- Sonos Beam Gen 2

This TV model has 3 HDMI ports all marked as ARC, not eARC, so I connected the two devices to two random HDMI ports, using the included HDMI cable for the Sonos as I expect it is the best possible for the soundbar (correct me if I'm wrong). For the Apple TV, I bought a 2.1 HDMI cable with eARC compatibility (pretty expensive IMO, but went for the best I could find).

I noticed the sound quality differs a lot on YouTube/HBO compared to ATV+ or Netflix. This difference consists in loudness and clarity of sound, I would say. After playing a lot with the settings and audio configurations, I managed to track this difference down to the fact that when the audio format is Dolby Digital 5.1 (on YouTube and HBO), the quality is WAY better than when in Dolby Atmos (ATV+ or Netflix). When in Atmos, everything is way quieter, duller, less immersive when compared to the other audio format. Everything was tested at 50% volume, and the audio format I got from the Sonos App for each test.

Regarding settings used:

On the TV side, the only setting I have for audio is 'Digital out format' that can be Stereo (uncompressed), Multichannel, or Multichannel (bypass). If I use Stereo, I get the audio format Stereo PCM (read from the Sonos app), and it is the loudest format out there, but I think the quality lacks. If I use one of the Multichannel options from the TV, I have access to the 2 Dolby formats.

On the Apple TV side, in Audio settings, I have set up the following: Audio Output - Receiver Speakers, Audio format is set to off (Audio will be decoded and sent to your equipment uncompressed multichannel LPCM), and here comes the difference: the next option is Immersive Audio, set up by default to Atmos. When it is with Atmos turned on here, I have access to the Dolby Atmos audio format in the 2 apps I mentioned at the beginning, and the sound loudness decreases a lot in those 2. If I put this setting to off, I stick with Dolby Digital 5.1 in all apps, and the sound quality is loud, crisp, immersive.

Bottom line, what I’m trying to figure out is how to use the Dolby Atmos format when possible and get better sound quality than Dolby Digital 5.1. I thought it is normal to be more quiet in Atmos, but the differences are too big.

Please help me figure out what is the issue I’m facing here and how can I try to fix it?

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1 reply

Userlevel 7
Badge +18

Hi @Rozovici 

Welcome to the Sonos Community!

Sorry to hear of your troubles with audio formats on your Beam.

The first thing I want to point out is that the HDMI-ARC connection on your TV is not capable of transporting Dolby Atmos (MAT) nor Multichannel LPCM from your Apple TV (or from TV apps, for that matter) - both of these formats require eARC. As far as I am aware, Apple TV is not capable of outputting Dolby Digital + (Atmos), which is the only format HDMI-ARC can carry that is an upgrade from standard Dolby Digital 5.1. Therefore, what the Beam does receive when using either of these option on the Apple TV is down to how your TV handles those formats coming from a source. It’s possible that it will convert Atmos (MAT) to Dolby Digital +, I suppose, but if it does, that’s the first time I’ve heard of a TV doing so. If the Sonos app reports playing Atmos in the Now Playing screen, however, then I suppose your TV must be doing exactly that.

Most likely, you will need to set your Apple TV to output Dolby Digital 5.1 - until you upgrade your TV to one with eARC - for best performance.

Note that unless you are playing purchased media on YouTube (like a movie), you will likely only ever get stereo audio - that may be why things sound different. Different streaming services could easily result in different quality too - if a service chooses to reencode the audio at a lower bitrate, you may well be able to hear the difference. Other than choosing a different service (or upgrading to Atmos capability), there won’t be anything you can do about this.

Bottom line, what I’m trying to figure out is how to use the Dolby Atmos format when possible and get better sound quality than Dolby Digital 5.1. I thought it is normal to be more quiet in Atmos, but the differences are too big.

Set your TV to output Dolby Digital +, and try to use apps built in to the TV whenever possible as your Apple TV will not output Dolby Digital +, as far as I am aware. Or, upgrade your TV (you could also use a device such as HD Fury Arcana to fit between the TV and your other devices, but doing so is unsupported by Sonos, and this is not a recommendation - just information).

I hope this helps.