If you have been searching for a soundbar and subwoofer setup that finally does justice to Dolby Atmos without turning your living room into a speaker warehouse, the Sonos Arc Ultra + Sub 4 combo is the system to put at the top of your shortlist. Sonos' flagship soundbar, paired with its next-generation wireless subwoofer, brings a genuine 9.1.4-channel home theatre experience to Indian living rooms in a two-box setup that takes minutes to install.
At 8mm, we have set up and calibrated Sonos systems across hundreds of homes in Raipur and beyond, and the Arc Ultra + Sub 4 has quickly become one of our most recommended combinations for anyone who wants cinema-grade sound with zero visible wiring and none of the complexity of a full AV receiver setup.
Why the Sonos Arc Ultra + Sub 4 Combo Stands Out
Sonos designed the Arc Ultra as a complete reinvention of its best-selling soundbar. Instead of stacking more of the same small drivers, Sonos introduced an entirely new bass technology called Sound Motion, built an all-new 14-driver acoustic architecture, and tuned the whole system for a wider, more three-dimensional Dolby Atmos presentation. Add the Sub 4, and you get a system that plays significantly louder, deeper, and cleaner than the soundbar alone, while remaining just as simple to set up.
● 9.1.4-channel Dolby Atmos from a single soundbar plus a dedicated wireless subwoofer for real low-end impact
● Sound Motion woofer technology delivers up to double the bass output of the original Sonos Arc
● Force-canceling dual woofers in the Sub 4 virtually eliminate distortion, buzz, and rattle even at high volumes
● Simple HDMI eARC connection to your TV, with Trueplay room tuning handled entirely through the Sonos app
● Expandable later with Sonos Era 300 speakers for a full wireless surround system
Sound Motion: The Technology Behind the Bass
The headline feature of the Arc Ultra is Sound Motion, a four-motor, dual-membrane woofer that replaces the multiple smaller bass drivers used in the original Arc. This flat, compact design lets Sonos pack significantly more bass output into a slimmer soundbar, while the force-canceling dual-cone construction keeps mechanical vibration and buzz to a minimum. The result is bass that feels far more substantial than the size of the cabinet suggests, whether you are watching an action sequence or listening to bass-heavy music.
Around the Sound Motion woofer, Sonos has arranged seven tweeters, six midwoofers, and dedicated up-firing and side-firing drivers across a total of 14 drivers, powered by 15 Class-D amplifiers. This is what allows the Arc Ultra to render a 9.1.4 Dolby Atmos experience — nine ear-level and side channels, one subwoofer channel, and four height channels — from a single bar without any additional speakers.
The Sub 4: Deeper, Cleaner Bass for Larger Rooms
The Sonos Sub 4 is the latest generation of Sonos' wireless subwoofer, built around dual 5-inch by 8-inch elliptical woofers that face inward toward each other. This inward-facing, force-canceling arrangement lets the two drivers move in opposite directions at the same time, cancelling out the vibration that would otherwise be felt through the cabinet, which keeps bass tight and controlled rather than boomy or muddy.
Rated down to approximately 25 Hz, the Sub 4 connects wirelessly over WiFi 6 to the Arc Ultra, automatically balances its output against the soundbar through the Sonos app, and can be placed upright beside furniture or laid flat under a console without any loss of performance. For anyone considering the full
For anyone considering the full Sonos Arc Ultra + Sub 4 combo, this is the single biggest upgrade over running the Arc Ultra on its own — particularly in larger living rooms or dedicated home theatre spaces where low-frequency extension matters most.
Sonos Arc Ultra + Sub 4: Key Specifications
|
Feature |
Sonos Arc Ultra |
Sonos Sub 4 |
|
Channel Layout |
9.1.4 Dolby Atmos |
Dedicated LFE / bass channel |
|
Drivers |
14 drivers (7 tweeters, 6 midwoofers, 1 Sound Motion woofer) |
Dual 5" x 8" force-canceling elliptical woofers |
|
Amplification |
15 Class-D amplifiers |
Dual Class-D digital amplifiers |
|
Frequency Response |
Extended low-end via Sound Motion |
Down to approx. 25 Hz |
|
Audio Formats |
Dolby Atmos, Dolby TrueHD, Dolby Digital Plus, Multichannel PCM |
N/A (bass handoff from paired speaker) |
|
Connectivity |
HDMI eARC, WiFi 6, Bluetooth 5.3, AirPlay 2, Spotify Connect |
WiFi 6, Ethernet (10/100) |
|
Room Tuning |
Trueplay (iOS & Android) |
Trueplay (via paired Arc Ultra) |
|
Voice Control |
Sonos Voice Control, Amazon Alexa |
N/A |
|
Expandable With |
Sonos Era 300 rear surrounds, second Sub 4 |
Pairs with Arc Ultra, Arc, or Beam |
Arc Ultra Alone vs. Arc Ultra + Sub 4 vs. Full Atmos System
Not sure how far to go? Here is how the three most common Sonos home theatre configurations compare, so you can match the setup to your room size and expectations.
|
Setup |
Best For |
Bass Performance |
Surround Immersion |
|
Arc Ultra (solo) |
Small to mid-sized rooms, bedrooms, apartments |
Strong for a single soundbar, thanks to Sound Motion |
Wide front and height staging, virtual surround |
|
Arc Ultra + Sub 4 |
Living rooms and dedicated home theatres |
Deep, room-filling bass with minimal distortion |
Full 9.1.4 Atmos with genuine low-end weight |
|
Arc Ultra + Sub 4 + 2x Era 300 |
Large rooms, serious home cinema setups |
Deep bass plus discrete rear channel output |
True surround with dedicated rear Atmos speakers |
Who Should Buy the Sonos Arc Ultra + Sub 4 Combo?
This combo is built for homeowners who want a genuinely premium, cinema-quality Dolby Atmos experience without running speaker wire around the room or investing in a separate AV receiver. It suits:
● Movie and streaming enthusiasts who want theatre-level bass and height effects for 4K Blu-ray, OTT, and gaming
● Living rooms where a full 5.1.4 or 7.1.4 wired system is not practical or aesthetically desirable
● Sonos households looking to build a whole-home audio ecosystem that starts with the TV and expands room by room
● Anyone upgrading from an older soundbar or a basic 2.1 system who wants a noticeable jump in scale and clarity
Setup Tips from the 8mm Team
A few placement and calibration details make a real difference to how this system performs in Indian living rooms:
● Position the Arc Ultra on a stable surface in front of and below the TV, with at least 4 inches of clearance to the screen, or use the dedicated wall mount
● Keep both ends of the soundbar at least 30 cm away from side walls for the width channels to project cleanly
● Place the Sub 4 away from corners where possible; corner placement can over-emphasise certain bass frequencies before Trueplay correction
● Always run Trueplay tuning after installation — it makes a measurable difference to how balanced the Arc Ultra and Sub 4 sound together in your specific room
● Use HDMI eARC rather than optical wherever your TV supports it, to get full lossless Dolby TrueHD Atmos rather than compressed Dolby Digital Plus
Experience the Sonos Arc Ultra + Sub 4 at 8mm
The best way to judge a home theatre system is to hear it in person. Visit the 8mm experience centre in Shankar Nagar, Raipur, to audition the Sonos Arc Ultra + Sub 4 combo for yourself, or reach out to our team for a room-specific recommendation, professional installation, and full Trueplay calibration.
Call us at +91 89829 27700 or write to contact@8mm.in to book a demo, get a personalised quote, or explore the full range of Sonos home theatre systems available at 8mm. You can also follow @8mmindia on Instagram for setup inspiration and real installations across India.
Ready to bring home the Sonos Arc Ultra + Sub 4? Shop the combo on 8mm.in and let our team handle the rest.
Frequently Asked Questions
1. What is the difference between the Sonos Arc Ultra and the original Sonos Arc?
The Arc Ultra replaces its multi-speaker bass array with a single Sound Motion woofer that Sonos says delivers roughly double the bass of the original Arc, adds three extra drivers for a 9.1.4 channel layout, includes Bluetooth for the first time, and runs about 20% more efficiently on standby. It is the flagship soundbar in the Sonos home theatre lineup.
2. Do I really need the Sub 4 with the Arc Ultra, or is the soundbar enough on its own?
The Arc Ultra's Sound Motion woofer already produces genuinely deep bass for a single soundbar, so it works well without a subwoofer in small to mid-sized rooms. But for larger living rooms, dedicated home theatre spaces, or anyone who wants the chest-thump of real cinema bass during action scenes, the Sub 4 adds meaningfully more low-end extension and headroom. This is exactly why 8mm packages the two together in the Sonos Arc Ultra + Sub 4 combo.
3. How many channels does the Sonos Arc Ultra support?
The Arc Ultra is built around a 9.1.4 Dolby Atmos channel layout — nine ear-level and side channels, one built-in subwoofer channel, and four up-firing height channels — reproduced through 14 individual drivers powered by 15 Class-D amplifiers.
4. What audio formats does the Arc Ultra support?
The Arc Ultra decodes Dolby Digital, Dolby Digital Plus, Dolby Atmos, and Dolby TrueHD (including Dolby Atmos in TrueHD), plus multichannel PCM over its HDMI eARC connection. It does not support DTS or DTS:X, so if your source content is DTS-only, it will not pass through in that format.
5. How low does the Sonos Sub 4 go?
The Sub 4 is rated down to approximately 25 Hz, using dual 5-inch by 8-inch elliptical woofers in a force-canceling, inward-facing configuration inside a ported cabinet, which keeps bass tight and largely free of buzz or cabinet vibration even at high volumes.
6. Can I connect the Arc Ultra to an older TV without HDMI eARC?
The Arc Ultra requires an HDMI ARC or eARC port on your TV for the primary connection; a legacy optical adapter is available separately but is no longer bundled in the box. For full, lossless Dolby TrueHD Atmos passthrough, an eARC-enabled TV is strongly recommended.
7. Does the Sonos Arc Ultra + Sub 4 combo support wireless streaming and multi-room audio?
Yes. Both products connect over WiFi 6 as part of the Sonos ecosystem, support Apple AirPlay 2, Bluetooth 5.3, and Spotify Connect, and can be grouped with other Sonos speakers around your home for synchronized multi-room playback through the Sonos app.
8. Can I expand this system later with rear surround speakers?
Yes. The Arc Ultra and Sub 4 combo can be expanded at any time with a pair of Sonos Era 300 speakers as wireless Atmos-enabled rear surrounds, turning the setup into a full immersive home theatre system without rewiring your room.
9. Is the Sonos Arc Ultra + Sub 4 combo good for music as well as movies?
Yes. Beyond Dolby Atmos movie playback, the system streams stereo and Dolby Atmos Music through Sonos app control, AirPlay 2, and Spotify Connect, with Trueplay room tuning ensuring balanced sound whether you are watching a film or listening to an album.
10. Where can I buy the Sonos Arc Ultra + Sub 4 combo in India?
8mm is an authorised Sonos dealer based in Raipur, Chhattisgarh, and stocks the complete Sonos Arc Ultra + Sub 4 combo with professional setup, room calibration, and after-sales support included.
Written by Yug Gupta | Audio Specialist at 8mm.in
