Sonos Arc Dolby Atmos 5.0 – the final review of a superb soundbar

Sonos Arc

We have properly tested the Sonos Arc now that the new S2 software is out of beta testing. The verdict – very good for the right use cases. But you need to understand the design rationale before deciding on Sonos over any other brand.

The new Sonos Arc and S2 app portend the new direction for Sonos. We covered that in our first look article here. I will only repeat salient points in this final review.

We discovered a few things about the Sonos Arc after adding the Sub Gen 3 and One SL ‘rear’ speakers. Things that prospective buyers need to consider as this shines in specific use cases.

Sonos Arc is for

  • Those with a recent 2019/20, 4K Dolby Vision/Atmos TVs
  • Access to adequate 4K Dolby Vision/Atmos content (Blu-ray and premium 4K streaming services)
  • Want to invest in this as part of a larger Sonos multi-room audio system.

For everyone else who have a typical non-Dolby TV, watch free-to-air channels and HD streams it simply is an expensive 2.0 stereo soundbar. There are far less costly alternatives.

Sonos Arc, Sub and One SL home theatre system

‘Multi-room’ sets Sonos Arc apart from Samsung, LG, JBL and other soundbars – EXCEED

My strongest advice is that is it probably overkill. That is unless you are looking for a whole-of-home Sonos music and voice assistant experience. By all means, buy it, but there are lower-cost TV soundbars that can match it for sound fidelity.

Speaking of fidelity – EXCEED

When Sonos was born in 2002, CD-quality 16-bit/16kHz was the bee’s knees. So Sonos added support for 22, 24, 32, 44.1 and 48kHz (sample rates).

To be fair, most MP3 music is still 16-bit/128kbps radio quality (otherwise the files are too large). If this does not mean a lot to you, read our Sound Signature tutorial here.

The new S2 software adds 24-bit, 44.1/48kHz, and FLAC/ALAC 1536kbps support for higher-resolution sound. And if you have the Sonos Arc – Dolby Atmos decoding (it down-mixes any extra Dolby channels to 5.0).

What is a Sonos Arc 5.0 or 5.1 system?

First we strongly suggest you read our “Dummies Guide to Dolby Atmos here. It clarifies what Atmos is and how you need to get several things right before you can actually get Atmos. The information below is a forerunner to that Guide.

Sonos Arc

A quick Dolby Atmos overview (number of Sonos Arc speakers/amps in brackets)

  1. Left-front (two full-range elliptical woofers, and a silk-dome tweeter = 3 speakers)
  2. Centre-front (two woofers and a tweeter for speech enhancement = 3)
  3. Right-front (ditto to left front = 3)
  4. Left-front up-firing (woofer but simulates the rear left speaker = 1)
  5. Right-front up-firing (ditto to left front upwards = 1)
Sonos Arc

That is the ‘5’ part. Its body acts as a pretty effective bass radiator, e.g. 5.0. Adding Sub ( Gen 2 or 3) makes it 5.1 and adds ‘room-shaking’ to movies.

Adding two rears (like Sonos One SL or other Sonos speakers) does not make it a 5.1.2 (as most reviews have incorrectly assumed). These just reinforce the front left/right channels, and you can independently adjust the volume and balance. This may be handy to add extra volume for hearing impaired.

Sonos One SL
One SL does not have voice assistance which is good for rear speakers!

The decoder sends the Dolby metadata to one or more of the five channels. So, if you hear a helicopter flying overhead, then it is moving ‘objects’ from one speaker to another. Sonos refers to this as five phased-array channels. We call it (as we do any soundbar that has all speakers in the one bar) ‘psycho-acoustic trickery’ to hack your ears to thinking that it hears 3D sound objects flying around you.

If you are interested, you can test the effectiveness of Dolby Atmos spatial sound here (requires Windows or macOS)

Why bass (Sub), mid-range, and treble (Tweeter) are not Dolby Atmos channels

Human hearing maxes out from a low of 20Hz (bass) to high of 20kHz (treble). Many older Australians may only hear to 100hZ to 3kHz, so they hear more muffled sounds!

Few speakers can reproduce 20-20 so dedicated speakers to help fill in either end. These are not Dolby audio channels but simple frequency cut-over.

Sub amplifies any bass below a cut-over frequency (adjustable on Sonos from 50/60/70/80/90/100/110Hz – leave it a 110). So, when you add Sub, you both hear and feel more bass (a combination of volume and air movement). Sub connects via Wi-Fi N 2.4Ghz or 10/100 Ethernet cable. It is 389 x 158 x 402 mm x 16kg and requires 240V power. It is worth adding to enhance the overall Dolby movie experience. Without it, you get reasonable, but not room-shaking bass from the Arc’s passive soundbar radiators

Sonos Sub
Sub is very good

Similarly, treble (tweeters) is a crossover frequency. This takes over from the main speaker to reinforce from around 4Khz to 20kHz.

That is why an equaliser (EQ) can change a sound signature. It can give more emphasis (+/- dB – volume) to the Sub or tweeters. The Sonos EQ has bass and/or treble boost only.

Dolby Atmos 5.0/1 – EXCEED

Dolby Atmos ‘3D’ sound goes with Dolby Vision (or HDR10/+). It is part of the metadta sound stream. You can only get Dolby Atmos sound on Atmos Blu-ray and some premium streaming services that support it.

For example where Netflix and other streaming services supports it you will see

But Dolby Atmos is solely not about adding ‘height’. It is about filling the room with precisely placed sound objects – a 3D sound stage. 

 This is really good at decoding most ‘Dolby formats’ and Atmos is very ‘convincing’.

  • Atmos 5.0 (128 audio objects mixed into a 5.0 channel system or downmix from higher formats)
  • TrueHD (8-channel audio and the default if an Atmos metadata is not present)
  • Digital Plus (7.1 used by Windows, macOS and tvOS – no metadata, audio channels only)
  • Digital 5.1 (no metadata, audio channels only, also called Dolby AC-3).

Sonos Arc ‘downmixes’ Dolby content to use from two to five audio channels and up to eleven speakers.

When it does not get Dolby content, everything else will play in 2.0 stereo – FAIL

Remember that most of the time your free-to-air TV or standard steaming will be PCM 2.0 stereo sound.

You may think FAIL is a harsh mark. All it means is this does not do what most 3D capable Dolby Atmos, DTS or PCM Multi-channel soundbars do.

Sonos is almost puritanical about providing sound as the author intended it. No synthesised ‘plastic’ sound (you can confirm that here). So, it does not support ‘simulated’ surround sound like DTS:X, DTS Virtual: X, DTS HD and PCM multichannel audio. When it does not get Dolby content, it reverts to PCM 2.0, and the two up-firing speakers reinforce low-end frequencies. Our recommendation for the Sub is only for Dolby Atmos content – it does little for other content or music.

Is it a bold move by Sonos? Joe and Jane Average will marvel at the faux simulated sound that you can get on almost any other Soundbar. And that brings me to the last point before we discuss how it sounds.

If you don’t have a recent 4K Dolby Vision/Atmos TV, then it is not for you

It does not have any HDMI inputs to connect Blu-ray players, games consoles or 4K set-top boxes. That means all these devices must connect to the HDMI ports on the TV. Then audio is passed through to the Sonos Arc for decoding.

Only the most recent 4K TVs have HDMI 2.0 or 2.1 that enables Dolby Atmos audio passthrough. Otherwise, all the TV will see is PCM 2.0 stereo, and that is all the Sonos Arc will play – albeit beautifully well.

Summary:

You should consider this

  1. If you have a recent 4/8K TV with HDMI 2.0/2.1 and eARC
  2. If you have access to enough Dolby Atmos content to justify it
  3. And you don’t care that it won’t do DTX or simulated 3D sound

TunePlay – fit the room

As we were using the Android App, we had manually tune the system to the room. This is easy and consists of the Arc, Sub and rears playing tones. You answer questions while seated in the normal listening position.

If you use an iPhone, you can use its microphone to eliminate manual tuning.

How does the Sonos Arc sound?

Brilliant on Dolby Atmos 5.0 and other lesser Dolby content. Clear, crisp, full-range sound with

  • Wide left/right sound stage/ Sound appears to come from at least a metre from each side. (TunePlay may help here)
  • Left/right up-firing speaker adds spatial rear sound. Sound bounces off the ceiling and appears to come from about 2-metres from the TV. But it gets progressively weaker as you move further away. (TunePlay may help here)
  • Adding a Sub adds ‘room-shaking’ effects – it can pump masses of air and is a worthwhile addition. Sub can be almost anywhere in the listening area including on its side under a couch
  • Not adding a sub means the soundbar produces bass via its passive radiators. it is fine for standard TV and audio use
  • Adding the rears does not expand to the Dolby sound stage – they are for reinforcement of the front L/R only.

Maximum volume at 2 metres is around 85dB with no perceptible harmonic distortion. Now, I would have thought that it should have been able to hit the mid-90s. But believe me, the maximum volume will get the neighbours complaining.

Dialogue enhancement adds a few dB to the upper-midrange. Listeners commented that it was a little clearer than the Samsung HW-Q90R.

Sonos Arc – Dolby Atmos content, default settings, rear speakers, at 2 metres

RangeArc (Sub)
Deep Bass: 20-40Hz
Middle Bass: 40-100Hz
High Bass: 100 to 200Hz
Low-mid: 200-400Hz
Mid: 400-1000Hz
High-mid: 1-2kHz
Low-treble: 2-4kHz
Treble:4-6kHz
High Treble: 6-1kHz
Dog whistle: 10-20kHz
Nil (starting)
Building to 107Hz (strong)
Flat
Ditto
Ditto
Slight decline but Flat
Slight decline but flat
Flat
Flat
Flat with a slight decline at 18kHz
Sonos Arc
Arc only – good bass for TV and music but not room shaking. Excellent treble.
Sonos Arc
Sub – Much stronger bass

We retested minus the rears, but they made no difference to volume or frequency response.

Content plays a huge part in the frequency charts. These prove that Sonos has truly achieved its aim of neither adding nor subtracting from what the audio producer wants.

We retested with music streamed from Spotify. The EQ can make a small effect when playing standard 2.0 TV, movie or music content. You can tweak it to Warm and Sweet (bass/mid boosted, treble recessed) or Mid: (bass recessed, mid boosted, treble recessed). This covers most non-Dolby Atmos scenarios admirably.

Objective listener with perfect hearing

I asked my wife to objectively listen to the Sonos Arc 5.1 and the Samsung HW-Q90R 7.1.4.

  • Samsung has better bass and a more expansive sound stage. It has separate rear left and right and upwards-firing speakers. (I stress that its not the best comparison between a 7.1.4 and 5.1)
  • Sonos has a slightly better clear dialogue.
  • Although a minor point she missed the ability to connect the Blu-ray and Media Centre to the soundbar. Two ugly HDMI cables were hanging down from the TV (eARC is concealed behind the wall).
  • But the final test is most telling – watching standard TV and streaming. Samsung provides a faux and DTS surround mode (if you select it) and that adds to the overall enjoyment. In this case, Sonos is just a 2.0 unit, albeit a very good one.

Voice Assistance

During setup, you can nominate audio and video content sources as well as link to a NAS device. You can also select Google Assistant (tested) and Alexa. AirPlay 2 enables Apple iPhone control and access to Apple’s music and movie resources.

OK Google worked flawlessly turning ‘Media’ on and off and playing from audio content sources. It offers everything that a Google speaker does.

Our test rig is a Sony A9G 65” 4K OLED 2019 (review here). Google was able to control the TV and the Soundbar via eARC. The Sony TV remote control was able to control the soundbar.

Competition

As I said, if you want a multi-room setup, there is no real competition in the mainstream brands.

But if you want a Dolby Atmos 5.1.2 or 7.1 .4 soundbar then these need to be on your shopping list.

Dolby Atmos 7.1.4
This is Dolby Atmos 7.1.4
  • Samsung HW-Q90R  7.1.4, 512W, 17-speaker (2019) $1999. Dolby Atmos and DTS, Sound upscale, 32-bit Hi-Res, BT, 2 x HDMI 2.0 in and 1 x HDMI eARC. Includes Sub
  • Samsung HW-Q80R  5.1.2, 372W 13-speaker (2019) $1499 as above
  • LG SN-11RG, 7.1.4, 770W, 12-speaker (2020) $1899 as above
  • LG SN-10YG , 5.1.2, 570W, 8-speaker (2020) $1599 as above

We compared the Samsung HW-Q90R with the full kitted Sonos Arc (in brackets)

Sonos Arc full kit white
  • Volume is higher at 90+dB with no apparent distortion (mid-80s)
  • Bass via the Sub is stronger and started at 34Hz (80Hz)
  • Dolby Atmos 7.1.4 sound stage is far more expansive (not a fair comparison as Sonos Arc is 5.1)
  • Clear speech adaptive sound enhancement (yes and Sonos is slightly better)
  • 2 x HDMI 2.0 inputs (none)
  • eARC (yes)
  • BT and Chromecast (AirPlay 2 and W-Fi on both)
  • Wi-Fi AC dual-band (single 2.4Ghz)
  • DTX and PCM Multi-channel decoding for faux surround (no)
  • Hi-Res 32-bit upscale (no)
  • No multi-room speakers (yes but you can use Google Assistant to achieve a ‘disparate’ multi-room system)
  • Room calibration (yes – LG has a similar tool)
  • SPDIF optical (yes)
  • Game Mode Pro (no)

I would have liked to compare it to the ‘truly remarkable fully-featured Sennheiser AMBEO 5.1.4  Dolby Atmos soundbar. (Thomas Bartlett’s review here). At $3999 it has Dolby, DTS, multi-HDMI ports, and makes coffee so this is not an apple with apple comparison. Still, I can salivate over it!

GadgetGuy’s take – Sonos Arc is for Sonos lovers that want whole-of-home solutions

I need to explain my conundrum as I quite like Sonos gear. It would be on my shopping list if I wanted a soundbar.

This set costs $2936 ($1399+999+538). I suspect that you could get away with just the Arc bar to start with. There is not usually a lot of discounting of Sonos. On a subjective value basis, Sonos loses points. But value is only part of the equation and is reinforced by the multi-room availability.

Samsung and LG do way more and cost $1499-1999 – less if you shop around. These win on points and sound very good. We rated the Samsung HS-Q90R at 5/5 – it is perfect even if you don’t have the right TV setup. We have not yet reviewed the LG 2020 range. These are at Thomas Bartlett’s undergoing tests, and I suspect these will rate highly too.

So, it comes down to cognitive dissonance. Good old US brand Sonos (speakers made in China). Or either of the South Korean companies with speakers hopefully made there.

Let me explain our ratings

  • Dolby Atmos 5.1 is 5/5
  • As part of a multi-room system 5/5
  • Sonos build, longevity and reputation adds points
  • S2 app and setup adds points
  • Voice assistance and Airplay 2 adds points
  • Lack of the rear sound stage depth loses points
  • No HDMI inputs loses points
  • Soundbar alone seems reasonable value, but the kit for $2936 brings means the Sennheiser AMBEO outclasses it (albeit $1k more)
  • Needing the right TV loses points – no Dolby Atmos without passthrough
  • Most will prefer synthetic DTS sound as well, so it loses points – it is an expensive 2.0 unit otherwise

Features
Value for money
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Sonos neutral sound signature for authentic Dolby Atmos
Can be part of a Sonos multi-room audio system
Great Sonos build and quality – it’s a keeper
Wall mount (with $99 optional brackets)
Only workswith the right TV(HDMI 2.0/2.1, eARC and high bit-rate passthrough)
No HDMI input ports
No BT (can stream over Wi-Fi)
2.0 stereo only on non-Dolby content
Rear sound projection is not as strong as it should be
Rears Sonos One SLs don’t turn it into a 5.1.2 system
4.3
  1. The information that the Arc is 5.0 in this article does not seem to be correct.
    The Arc by itself is 5.0.2
    The 5 are Center, left front, right front, left rear, and right rear.
    The .2 are the up firing speakers.
    When you add physical rear speakers, the system is still 5.0. The Arc’s left rear and right rear will then be used to help out the front right and left front speakers.

    1. Sorry, but it only has five channels. 1) Left, 2) Centre, 3) Right and the 4) left and 5) right up-firing make 5.
      I raised this with Sonos that affirmed it is a five-channel implementation of Dolby. It can be 5.1 with the Sub (that uses frequency crossover – it is not a Dolby channel) and adding surrounds still make it 5.1 – all the surrounds so is replicate the front left/right.
      Yes it is confusing – was to me too.

      1. Ray, in your first look article on the Arc, you correctly called it as 5.0.2. Why would you misunderstand now?
        There is center channel, the 2 L R channels (handled by the oblique facing woofers), the 2 rear L R channels (handled by the 2 side firing woofers at the ends of the Arc). Those are the 5 of the 5.0.2.
        The two upward firing woofers are the height channel which makes it Atmos. Those are the .2 of the 5.0.2.
        Please recheck the facts.

        1. I have edited the original announcement article to reflect 5.0 based on Sonos’s information. I have asked Sonos to fact check and it has come back: [my comments in square brackets]
          All Dolby Atmos content pass-through is a baseline 5.0.2, not 5.0. [This is if the TV has the ability to pass through Dolby Atmos 5.0.2 content/signal to Sonos for it to redistribute to 5.0 channels – remember that the Sub works on crossover frequency)
          All Dolby (non-Atmos) content passed through the Arc is 5.0 as standard as a baseline. [This means that if a non-Dobly Atmos, but still a Dolby Digital signal is received it is passed through up to 5.0 – that is not an Atmos format. Faux 3D DTX signals are passed through as PCM 2.0)

          Sonos is 5.0 because the two (Left/Right) upwards-firing front speaker receive the Dolby Atmos 4) rear left and 5) right channels. They bounce this off the ceiling to throw it behind the normal sitting position as determined by TruePlay tuning. They are not what Dolby calls the X.X.2 or .4 channels that are front left overhead, rigth left overhead, rear left overhead and rear right overhead.
          Yes – damned confusing even for intelligent people like us.

          1. Thanks for the quote from Sonos!
            They said Atmos Donald is 5.0.2.
            The square bracket comment is not correct. Where did you get it from? Can you show where does the Sonos reply imply that?
            Thanks!

  2. I thought dolby atmos itself adds ceiling channels.. otherwise its only regular surround..
    What i know arc up firing speakers are actually for these channels.. how you can manage rear channels? From my opinion only by adding rear speakers (either one sl or ikea ones). So if you want full atmos you need to buy whole system with one sl, thats why they sell it as a set.

    1. We are trying to clarify that with Sonos. What we know for sure. It has five audio channels only and Sonos has said that this is left, centre, right and the two up-firing are actually allocated to 4)left and 5)right rear – not overheads. They are to bounce sound to appear to come from behind – not so much from overhead. Sonos explains that it can create the feel of Dolby Atmos by shifting objects around the ‘five-phased-array’. It has confirmed that f you add physical rears, the two front up-firing speakers cease to work as channels 4 and 5 and reinforce lower frequency. Please wait until I get more in writing from Sonos.
      PS – This is no different from any other all-in-one soundbar that offers 5.0/.1.

      1. Arc = 5.0.2
        Arc + Sub = 5.1.2
        Arc + Sub + Surrounds = 5.1.2

        The reasoning for this is the side-firing drivers simulate surrounds when there are none bonded to the Sonos Arc. When you add surrounds the side-firing drivers switch to playing the left and right channels to widen them and the surround audio becomes true surround.

        That’s official reply to my email from sonos…

        Cheers

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