Sonos Arc Ultra soundbar – Add Sub 4 and Era 300s for Dolby Atmos on steroids (AV review)

The new Sonos Arc Ultra and Sub 4 replace the venerable Sonos Arc and Sub 3, which already provided an excellent Dolby Atmos and surround sound experience. Add a pair of Era 300 rear speakers for true Dolby Atmos and surround sound on steroids.

The original Sonos Arc 5.0.2, circa June 2020, was one of the few soundbars to decode Dolby Atmos content without compression or a lower bit-rate format. Adding the Sub Gen 3 and a pair of One rear speakers (read Sonos Arc Dolby Atmos soundbar with optional Sub and surrounds) gave a superb 5.1.2 Dolby Atmos experience.

Sonos realised it needed that extra rear left and right up-firing boost for immersive Dolby Atmos.

With the introduction of the Sonos Era 300 5.0.1 speaker circa 2023, a pair used as rear speakers turned the Arc into a 7.1.4 Dolby Atmos system that until now, is the best DA sound we have ever heard. Read Sonos Era 300 as rears to the Sonos Arc – superb Dolby Atmos 7.1.4 soundbar)

Why? Each Era 300 speaker (as a stereo pair) added 5.0.1 left/right stereo, left/right surround, centre forward firing, and up-firing to deliver full-spectrum Dolby Atmos sound.

One important point needs to be emphasised. The Sonos app is the secret sauce, seamlessly adding Sonos speakers (One, Five, Era 100, or Era 300) as stereo pair rears to the Arc via Wi-Fi or, preferably, Ethernet.

Now that the Arc has been superseded by the Arc Ultra 9.1.4 and the Sub 3 by the Sub 4, I badly covert them. Not because the sound is so much better but because they add that little je ne sais quoi to the already class-leading Dolby Atmos system.

The Catch22—the Arc Ultra, Sub 4, and a pair of Era 300s cost $4596! The question is, how much better is it than, say, a Samsung 11.1.4 or JBL Bar 11.1.5 Dolby Atmos system at half that price? Let’s try to answer that later.

Further reading:

• How to buy a soundbar that meets your needs?
• Five tips for better TV sound – Dolby Atmos for beginners

Australian Review: Sonos Arc Ultra and Sub 4 with Era 300 rear speakers

Website	Sonos Arc Ultra Product Page and Support Page    Sub 4 Product Page and Support Page Era 300 Product Page  and Support Page
Colour	Sonos Soft White or Black matte
Price (3/12/24)	Arc Ultra $1799 Sub 4 $1299 Era 300 each $749 Bundle $4596
From	Sonos Online, Harvey Norman (and sub-brands), JB Hi-Fi, Good Guys, and select sound system retailers. See store locator.
Warranty	12-months ACL and 30 days free return and exchange
Made in	US-designed and made in China.
About	Sonos is an American Audio company based in Santa Barbara, California [Est 2002]. It develops and manufactures smart speakers to play music simultaneously in multiple rooms.
More	CyberShack Sonos news and reviews

We use Fail (below expectations), Pass (meets expectations) and Exceed (surpasses expectations or is the class leader) against many of the items below. We occasionally give a Pass(able) rating that is not as good as it should be and a Pass ‘+’ rating to show it is good but does not quite make it to Exceed. You can click on most images for an enlargement.

First Impression – it is all about Sonos

If you don’t know Sonos, you will likely buy a Dolby Atmos soundbar from LG, Samsung, or JBL—and you will be delighted. However, you cannot compare Sonos to the others as the technology and experience differ vastly.

It uses very different approaches to speaker, amp, and enclosure design and an app that adds far more features and value than the consumer brands.

Where most soundbars decode an eARC signal and wirelessly transmit it to the rear speakers, Sonos injects that signal into the home Wi-Fi network. The rear speakers are connected to the soundbar via Wi-Fi or Ethernet. This has made Sonos the leader in multi-room speaker systems and made the Arc/Arc Ultra so expandable.

It is 1178 (W) x 110.6 (D) x 75 (H) and 5.9kg. The $129 Sonos Arc Ultra Wall Mount bracket is for wall mounting.

What is inside the Sonos Arc Ultra?

It has 15 Class-D amps powering a 9.1.4 virtual Dolby Atmos experience. We say virtual because, as a single soundbar, it relies on psychoacoustics to bounce the surrounds off adjacent walls and height sounds off ceilings to create a virtual experience.

• Left/Right stereo forward-firing woofers 2.X.X
• Left/Right wide side-firing speakers 2.X.X
• Left/Right surround angled-firing woofers 2.X.X
• Centre forward firing tweeter 1.X.X
• Left/Right stereo forward firing tweeters 2.X.X
• Left/Right up-firing tweeter X.X.2
• Left/Right angles tweeters X.X.2
• Sound Motion up-firing sub-woofer X.1.X

The problem is that few homes have the right psychoacoustics. Sonos realises that most buyers will use Era 300 rears for an actual DA experience. Adding these does not change the 9.1.4 DA decode but allocates and phases DA sound objects to the correct front and rear speakers, eliminating the need for psychoacoustics.

Sonos App is the secret sauce

In May 2024, Sonos released a completely new app to add new features (Sonos headphones Sonos Ace – Superior over-the-ear, BT, ANC headphones for Sonos lovers) and replace its rock-solid S2 app. The only problem is that it was uber-buggy, which enraged the Sonos community, used to quiet enjoyment of bullet-proof Sonos speakers. Tar and feathers flew!

I am pleased to say that 99.9% of the issues have been solved – read Sonos app issues – sorry and a commitment to fix it all real soon, so please don’t consider old ‘flames’ about the app.

Setup is easy

Connect the Sonos Arc Ultra to power and the TV eARC port. It will work on older ARC but may compress the Dolby Atmos (DA) stream. In this mode, it is a straight soundbar.

Open the Sonos App for Android or iOS and make sure your phone or tablet is on the 2.4GHz Wi-Fi channel. Some Sonos devices can use 5GHz as well, but music, movies, and Dolby Atmos only need 2.4GHz.

You can connect the soundbar via Wi-Fi, but we strongly recommend using an Ethernet cable to the router. Wi-Fi either works or not, and most cheap routers won’t!

Ethernet is easy to use, and we refer you to ways to do that in a separate article.

You will also need a pair ($69 each) of Sonos Ethernet and 3.5mm to USB-C combo adapters for the Era 300, but the Arc Ultra and Sub 4 have RJ-45 ports.

Add the Sonos Arc Ultra to the app and allocate it to a home and room (for multi-room use).

If you have the Sub 4, ditto. Again, it is better to connect it via Ethernet.

Add the Era 300s one at a time, ditto. Then, use the app to stereo-pair and then add it to the Sonos Arc Ultra as Surrounds (left and right).

Once set up, run Trueplay to map the room and optimise sound.

You can adjust the EQ and the strength of the Surround, Height and Sub.

There is a setting for Spatial Music upmix that adds a new dimension to 2.0 to 7.1 sound.

I recommend Sonos for hearing-impaired listeners. It can add three levels of speech enhancement and a night mode that reduces loud noises and focuses on speech.

It supports Alexa and Sonos Voice Control via its far-field mics (tested to 6m).

Bluetooth 5.3 and Wi-Fi streaming – superb

When HDMI is inactive, you can use this as a Bluetooth speaker (soundbar only) or for Wi-Fi streaming (soundbar, sub, and rears), including High-definition and Dolby Atmos content. The sound is rich, full, deep, clear and clean! It also supports Apple AirPlay2.

Add Sonos Ace Headphones

It supports TV Audio Swap from the soundbar to the headphones. Ace adds exceptional ANC or Aware Mode and spatial audio with dynamic head tracking for Dolby Atmos and other 3D spatial content.

To be clear, Sonos still needs to figure out how to use the Sonos Ace simultaneously with the Arc Ultra. This would be a significant boon to the hearing impaired if it does.

 Sound codecs

• Mono 1.0 or stereo 2.0
• PCM 1.0 to 7.1
• Dolby Digital, Dolby Digital Plus 2.1 to 7.1
• Dolby Atmos (Dolby Digital Plus), Dolby Atmos, Dolby TrueHD, Dolby Atmos (True HD). It decodes 128 sound object metadata and mixes to 9.1.4.
• DTS Digital Surround to 7.1 (Not DTS:X).

Energy use – Pass

At maximum volume, it consumes 33W. It usually sits below 20W and draws <1W in sleep mode. We did not measure the Sub or Eras but assume at least another 60W when active.

Sub 4

The only physical difference between the Sub Gen 3 and Gen 4 is that the latter has slimmed to 11.79 kg (was 13.15kg). It works with Arc Ultra, Arc, and Beam or as a standalone sub with Era 300, 100, or Five. You can have two subs, including a mix of Gen 3 and 4.

Sound starts at 25Hz, and the cut-over (not disclosed) depends on the attached speakers and Trueplay tuning. We suspect 80-100Hz for the Sonos Arc Ultra and around 150Hz for the Era 300.

Compared to the Sub Gen 3, there is slightly more “low rumble’.

How does the Sonos Arc Ultra sound?

We tested in three modes: the app was set to defaults, Trueplay was run before each iteration, and a white noise generator was used at maximum volume.

• Sonos Arc Ultra
• With Sub 4
• With Sub 4 and 2 x Era 300 rears.

Soundbar only

While there were hints of low-bass, it meant little until mid-bass kicked in at 50Hz. So, there was no room-shaking low-bass but nice, clear thumps instead of whumps.

It was flat from 50Hz to almost 20kHz – this is a neutral sound signature that neither adds nor subtracts from the input. It also allows an EQ to recess bass, mid or treble to produce most signatures.

There was a slight amount of clipping/compression from 500-2000Hz.

Soundbar and Sub 4

Low-bass kicked in at 25Hz with some vengeance, offering outstanding room-shaking bass that built to 50Hz and then flattened out to 20kHz. We detected an ever-so-slight cutover to the soundbar around 85Hz.

You buy the sub because you want room, shaking clear bass.

Soundbar with Sub 4 and 2 x Era 300.

It does not change the overall sound signature as much as it lets each speaker do what it does best. For example, we saw a slight reinforcement of the mid and high treble that added even more air and definition – as if you were there.

Sonos has done a remarkable job with Trueplay to bring out the best from all three scenarios.

Maximum volume

It is the usual 80dB over Bluetooth. Over HDMI, it can reach 85dB, and Wi-Fi nearly 90 dB. There is no perceptible distortion but some minor clipping that can be cured by backing off to 80% volume.

Music

Soundbar only: If you disable Spatial Music, you get one of the most precise 2.0 left/right channel placements I have heard.

With spatial music enabled, I was wowed. I listened to the Blues Brothers for deep bass and jazz, Manhattan Transfer for treble and synth, and Beachboys for strings and vocals. The sound stage was huge—far wider than the soundbar.

Sub 4: Overpowering, and I found that somewhere between 0 and 2 (it can go to +15) was okay, depending on the music genre.

With the Era 300 rears: The impact was double wow. It separated the front-centric vocals from the instrumentals and played a balanced pseudo 7.1.

Read How to tell if you have good music – sound signature is the key.

TV including up to 7.1 surround sound

As most content is 2.0 or 5.1 2D surround, switching on Spatial content is a no-brainer.

It implicitly knows what sounds should come from the front and sides, but without a suitable psychoacoustic room, it simply results in a wider front-centric sound stage.

Add the Era 300 rears, and that implicit knowledge of where to place 2D sound over 15 soundbar speakers and 12 Era 300 (2 x 6) speakers is extraordinary. Add to that adjustment for TV and Music ‘immersiveness’ and it makes surround sound quite remarkable. All that is missing is 3D height.

Dolby Vision/Atmos 3D spatial content

As a soundbar, it is front-centric unless you have a perfect psychoacoustic room, which few do. It tries to cast sound back to the seating area but is not immersive. It needs the Era 300 rears.

Now you have 28 separately addressable amps to distribute 9.1.4 sound. It creates about a 3.4m (more on placement later) Dolby Atmos sound envelope around the seating area and a decent spatial experience far beyond that (e.g. in open-plan living/dining/TV areas. It is so good that we ducked a ‘bullet’ while sitting about 6 metres away at the dining table.

Placement

The TV screen should be at seated eye height, and the soundbar should be about 10cm below that. The best case is wall-mounted, but you must consider cable management for Ethernet, power, and HDMI eARC (it does not have HDMI).

The Era 300s are large, at 260mm x 185 x 160 (W/H/D) and 4.47kg each. Some say the design is polarising, but I don’t mind it.

We placed them behind a three-seater couch about 3 metres (ideal 65” 4K viewing distance) from the TV/Arc Ultra. The questions are how far behind and apart they should be and whether they should be angled towards the listener.

We have been experimenting. While Trueplay can compensate quite well, the speakers are best placed about 70-80cm high, 60cm behind, and at least 30cm beside each end of the couch. They should be angled about 20° toward the listener. Ensure you run Trueplay every time you experiment. I suspect the Sonos Era 300 stand ($449 pair), 965mm high, may be the best answer.

CyberShack’s view: Sonos Arc Ultra, Sub 4 and Era 300s for Dolby Atmos on steroids

As far as a 9.1.4 standalone soundbar goes, it is a premium offering. It relies on psychoacoustics to bounce the sound around the viewing area, but few homes have suitable acoustics. The new integrated Sound Motion subwoofer is good but does not give room-shaking sound. For that, you need the Sub 4, one of the more powerful subwoofers we tested.

Subjectively, as an all-in-one 9.1.4 soundbar, it is better than any other, including the exceptional $2499 Sennheiser Ambeo Max (5.1.4) that can have an optional $1999 sub-woofer but no rear speakers. Or the $1499 Bose Smart Ultra 5.0.2 plus $529.95 surrounds and $699.95 Bass module 500.

But I want the best Dolby Atmos experience! The real Dolby Atmos 9.1.4 comes from adding a pair of Era 300s rears, which build the most convincing DA envelope we have yet heard.

Add to that the Wi-Fi/Ethernet multi-room and speaker connection, and it is in a class of its own.

Now, if you don’t have a spare $4.5K, you will be very happy with

• Samsung HW-Q990D 11.1.4 Dolby Atmos soundbar – simply stupendous
• JBL BAR 1300 – 1170 Watts, 11.1.4 Dolby Atmos soundbar
• Samsung HW-Q930D 9.1.4 – more than you need for true Dolby Atmos
• LG S95QR 9.1.5 Dolby Atmos

at less than half the cost.

Do they provide the immersive DA that Sonos can? They are good, but no cigar. It is like trying to compare the performance of a Toyota to a Porsche.

Summary: The Sonos Arc was our best DA experience until the Sonos Arc Ultra trounced it. It is not that the original Arc/Sub/Era 300 rear combo is lacking in the 7.1.4 DA department, but that the new 9.1.4 Sub/Era combo is so much more precise and immersive, and the DA bubble is just that much more convincing.

Rating

This is hard because we have three combos – Sonos Arc Ultra, with Sub 4 and ultimately 2 x Era 300 rears.

Subjectively, the soundbar gets a 9/10, and the combo gets a 10/10—and at that price, it should.

• Features: 90—Bluetooth, Wi-Fi, Ethernet, a comprehensive app, and Wi-Fi speaker expansion—what more could you want?
• Value: 90—It’s the premium and costs what it costs. If you have to ask the price, buy a standard Dolby Atmos 9.1.4 or higher at less than half the cost.
• Performance: 95—Judged purely on its DA ability over 28 speakers (combo), this is the best DA soundbar.
• Ease of Use: 90 – Easy to install and configure.
• Design: 95 – White or Black and a pervading feeling of premium.

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