STEREO GUIDE verdict
The Sonos Arc Ultra and Sonos Sub 4 are a perfect combination. They combine the usual Sonos functionality with automatic calibration and practical setting options. Even without the wireless subwoofer, the soundbar delivers an amazingly rich sound.
Pros
- Natural sound with a rich bass foundation
- Practical setting options and true play measurement
- Soundbar produces decent bass even without a subwoofer
- HDMI eARC connection
Cons
- Height and rear localization not convincing
- No analog input
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Tonal balance / transparency9.2
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Bass / Dynamics9.4
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Spatial imaging8.8
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Usability / Connectivity9.5
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Price/Performance9.4
Sonos soundbars have earned an excellent reputation over the years by combining compact dimensions with a full, natural sound. With the new Sonos Arc Ultra and the complementary Sonos Sub 4 wireless subwoofer, the American multi-room pioneer is now targeting home cinema enthusiasts who place great value on both room-filling sound and aesthetic design. The price of the soundbar-subwoofer combination is significantly higher than the Sonos Beam 2 and Sonos Sub Mini combination reviewed two years ago. Although the compact Beam 2 was already able to offer Dolby Atmos 3D surround sound, it did not provide a higher level of stage imaging – not to mention helicopters or jets over the heads of the audience.
Design and materials
The Sonos Arc Ultra measures 1.18 meters in width and is therefore suitable for many medium-sized to large TV sets, especially those with a 55-inch screen diagonal. The housing is available in black or white and remains true to the brand’s discreet, functional design. Instead of angular plastic elements, Sonos relies on softly flowing shapes and radii and a discreet perforated metal grille that covers the front and top.
The minimalism also applies to the operating concept. You won’t find a real display on the Arc Ultra. Only a color-changing LED above the Sonos logo indicates the operating status. This is not exactly intuitive to use, but does not distract from what is happening on the screen. If you want to find out more about playback mode, volume or input sources, you can access the corresponding Sonos app. This philosophy reflects the manufacturer’s approach: minimalism in the device itself, comprehensive control via software.
Operation and connections
Three touch-sensitive buttons are located on the top of the wireless soundbar: Voice assistants can be started on the left(Amazon Alexa or the in-house Sonos Voice Control), play/pause and track forward and back are located in the middle, and the volume can be controlled on the right by tapping or swiping. The rear of the Sonos Arc Ultra has more rounded contours. This is where the threaded sockets for wall mounting and air outlet openings for the large integrated woofer are located. Depending on the placement – wall mounting or lying on a TV cabinet – the ventilation is directed downwards or to the rear.
Inside the new, fully active Dolby Atmos soundbar from Sonos are 15 Class D digital amplifiers that drive each speaker chassis directly. A total of seven silk dome tweeters are not only responsible for clear treble and speech reproduction, but also for spatial imaging. Two of these radiate upwards as Atmos treble channels and are intended to provide a three-dimensional sound experience. Six mid-range drivers plus an array of two oval woofers, each with dual drives, complete the lavish speaker configuration of Sonos’ large soundbar.
Contemporary connectivity: Arc meets eARC
For signal transmission, Sonos relies on an HDMI eARC connection, which is offset inwards to the side together with the power cable. This simplifies cable routing, as both cables can be routed inconspicuously to the bottom or rear. If you want a particularly stable network connection, use the Ethernet socket. Alternatively, you can integrate the sound bar wirelessly into your home network. Last but not least, there is a Bluetooth button for wireless pairing of mobile devices that do not support AirPlay. The device’s integrated microphone array can be physically deactivated using a slide switch on the back. This should please users who are suspicious of voice assistants such as Amazon Alexa and Sonos Voice Control.
Speaking of voice assistants: While Alexa sends the voice commands to an external server for recognition after linking them to the user’s Amazon account, raising concerns about data protection, Sonos Voice Control processes the commands on board the soundbar. However, as with the Era 300 review, Sonos’ own voice control only understands and speaks English or French. Recognition of the respective wake word worked in the review – as usual with Sonos – even from a distance and at a decent playback level. The sound then fades out and commands are reliably recognized.
This is a safe way to redirect the sound from Arc to Ace
The Arc Ultra has a goodie in store for perfect interaction with the Sonos Ace headphones, which we have already dedicated a review to. Simply press the content button on the closed over-ear to switch the sound from the Arc Ultra to the headphones and enjoy a private movie theater experience. A useful feature that also allows intensive listening late at night without stress from roommates or neighbors.
Sonos Sub 4: Compact subwoofer with style
The complementary Sonos Sub 4 is similarly simple, but also cleverly designed. Instead of a sober cube shape with sharp edges, they have opted for a housing with rounded corners and a striking oval opening in the middle for the air outlet of the two woofers positioned opposite each other. Sonos even advises using the opening as a handle, which makes positioning easier. At 39 × 40 × 16 centimeters, the Sub 4 remains pleasantly compact. However, the subwoofer weighs around 12 kilograms. The controls are limited to one button and a status LED. As with the soundbar, all other settings are made via the app. The woofer is extremely flexible when it comes to placement: it can stand freely, but also works with a wall behind it. The Sub 4 can even be operated horizontally. This is ideal for concealing it under a couch.
Two oval woofers (12 × 20 centimetres) work inside on two differently tuned bass reflex channels. This means that the Sub 4 covers a considerable low bass range, but can make the cabinet narrower than would be possible with classic, round 25-cm cones. The exact amplifier power remains a secret, Sonos only refers to the internal DSP power and the quad-core processor. Such restraint seems to be an American tradition in the hi-fi sector. The well-known US competitor Bose also usually refrains from providing wattage figures, which are also popular in advertising texts and at regulars’ tables.
Take two
If you attach particular importance to the lowest frequencies or want to provide sound in a very large room, you can even combine two Sonos Sub 4s with an Arc Ultra. This not only increases the maximum level, but also enables clever positioning in the room to get a better grip on booming or cancellations.
Sonos app: everything under control
The setup process inevitably takes place via the Sonos app for iOS and Android, as the Americans have, as usual, dispensed with a classic remote control. As a new buyer, you first have to create a Sonos account in order to pair the soundbar and subwoofer and install any firmware updates. Although this step is not entirely free of effort, it opens up enormous flexibility. You can use the “Trueplay” room adjustment function, which accesses both the microphone in the smartphone and the integrated microphones of the Arc Ultra. In acoustically well-damped rooms such as the home theater listening room at LowBeats, where we conducted the review together with our colleague Raphael Vogt, Trueplay has a rather subtle effect. In sub-optimal environments, however, the proven room correction can make a significant contribution to improving the sound.
If you want to adjust the sound balance to your own taste, the Sonos app offers bass and treble controls as well as adaptive loudness control, which is activated by default. This helps Sonos devices to produce a lively and rich sound even at low volumes without being too loud at high levels.
Sound test: Sonos Arc Ultra with and without Sonos Sub 4
The Sonos Arc Ultra already offers a rich and deep sound by default. As is generally the case with the brand, the developers have also succeeded in creating a harmonious sound setup for their large Atmos soundbar with natural, differentiated voice reproduction for vocals and dialog.
If you place the voice on the individual channels with Dolby Atmos test tracks, the Arc Ultra sets an exclamation mark against the Bose Smart Soundbar 600 or the JBL Bar 1300, which were reviewed in the same room some time ago, with a clear, phase-correct reproduction of the center channel. The two front channels can be located to the left and right of it. Sonos has fortunately dispensed with excessive processing, which impairs the sound purity and localization of many competitors’ soundbars. The stage appears wider than the bar. However, in a low-beat listening room, it takes a lot of imagination to localize the Atmos channels higher than the base. The same applies to the surround channels, which seem to be in front of you rather than behind you.
So if you want to experience real surround sound or Dolby Atmos, you won’t be able to avoid additional surround speakers such as the Era 300. Many users won’t miss the subwoofer at all. The Sonos Arc Ultra sounds surprisingly rich and powerful on its own. In the frequency range around 50 to 60 Hertz, the soundbar even noticeably boosts the signal. This provides a powerful foundation for music and movie sound that many listeners will find pleasantly rich.
Sub 4 makes more of it
If you add the Sub 4, the combination gains precision in the bass range, as the soundbar then has less responsibility for the low frequencies. And because larger woofers are used in conjunction with more cabinet volume. The punch is really “official” for such a living room-friendly home cinema system, as are the depth and precision.
The phase position is interesting here. The Sub 4 plays out of phase with the soundbar ex works, which can result in a certain amount of cancellation around 80 hertz if it is placed directly below or close to the soundbar. Trueplay tries to compensate for this automatically, but if you listen more closely, you will find that switching the phase manually in the app settings often produces a cleaner result. When set up correctly, the sub merges almost seamlessly with the Arc Ultra, which makes the presentation of bass drums, deep movie explosions and similar effects appear much more natural.
Music and movie playback
Once the system has been set up, the combination of Arc Ultra and Sub 4 is a convincing sound ensemble – both for music and in the home theater. With music streaming from services such as Qobuz, Spotify or Apple Music, a wide yet focused stereo sound stage can be heard. Despite its flat design, the soundbar appears surprisingly “big” and is particularly impressive at medium and high volumes.
With surround sound (Dolby Digital+, Dolby TrueHD or Atmos), the Arc Ultra emulates a 9.1.4 setup, which in many cases already creates sufficiently immersive effects. Although height channels always remain a certain area of compromise due to ceiling reflections or virtualization, the sound components from all directions sound coherent and low in coloration. If you are looking for maximum effects, buy additional Sonos speakers such as the Era 300 as rear channels.
The Qobuz playlist with some test tracks from our sound test
Conclusion and alternatives: Sonos Arc Ultra with Sonos Sub 4
With the Sonos Arc Ultra and the accompanying Sub 4, the multi-room pioneer shows once again that spatial and powerful home cinema sound, living room friendliness and intuitive app control do not have to be mutually exclusive. The soundbar impresses with its curved housing, simple operation via app and a sound profile that has a natural effect with music and scores with powerful bass dynamics for movies. Especially in combination with the Sub 4, the system doesn’t need to shy away from comparisons with less discreet and space-saving ensembles such as the JBL Bar 1300 in terms of bass reproduction and level stability. However, despite its lower price, the JBL Bar 1300 already comes with discreet wireless speakers for the surround channels, which can even be paired with a smartphone as mobile Bluetooth speakers with a rechargeable battery for listening to music.
If you want to stay in the Sonos universe but want even more immersive sound, you can add rear speakers such as the Sons Era 300 to achieve an even more spatial home theater effect. Overall, Sonos delivers a very well thought-out, mature-sounding set. A home theater sound system that is both visually and acoustically impressive and can be integrated into both small and medium-sized living rooms.
Technical specifications Sonos Arc Ultra + Sonos Sub 4
- Manufacturer’s recommended retail price: 1,000 euros (Arc Ultra) + 900 euros (Sub 4)
- Dimensions (W x H x D): 117.8 x 7.5 x 11.1 cm / 40.2 x 38.9 x 15.8 cm (soundbar / subwoofer)
- Subwoofer weight: 5.9 cm / 11.8 kg (soundbar / subwoofer)
- Special features: LAN, WLAN, HDMI eARC, Trueplay calibration
