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Sonos Sub 4 vs Sub Gen 3: Should You Upgrade or Grab the Discounted Flagship?

Sonos’s flagship subwoofer has a new member: the Sub 4, launched in late 2024 alongside the Arc Ultra. It sits directly above the Sub (Gen 3), Sonos’s flagship sub since 2020. And here’s the thing most comparisons dance around: Sonos itself says the Sub 4’s acoustic architecture is carried over from the Sub Gen 3. Same drivers, same amps, same 25 Hz floor.

So this isn’t a “which sounds better” question. It’s a generation decision: electronics, connectivity, longevity, and value. Both audiences get clear answers below.

The short answer

• Own a Sub Gen 3 already? Keep it. The bass output is effectively identical. None of the Sub 4’s changes alter what you hear, and there is no meaningful sonic reason to replace a working Gen 3.
• Buying new today and prices are close? Buy the Sub 4. It’s the current generation — Wi-Fi 6, more processing headroom, up to 50% lower idle power, and a longer support horizon. When the price gap is small, the newer box wins.
• Buying new and a refurbished or discounted Gen 3 is substantially cheaper? Buy the Gen 3 — especially refurbished. Sonos Certified Refurbished units carry the same one-year warranty as new and deliver the same bass. This is the single best value in the Sonos sub lineup for medium and large rooms.

If your question is actually “which size sub do I need for my room,” that’s a different decision — read our Sub Mini vs Sub 4 comparison first. This post is about choosing a generation within the same flagship size class.

What stayed the same: the shared acoustic architecture

Per Sonos’s own launch materials, the Sub 4’s acoustic design was carried over directly from the Sub Gen 3. That means the parts that produce bass are unchanged:

• Dual Class-D digital amplifiers, tuned to the subwoofer’s acoustic architecture
• Dual 5″ × 8″ elliptical woofers facing inward for a force-cancelling effect that virtually eliminates cabinet vibration and distortion
• Ported cabinet that enhances bass response
• Frequency response as low as 25 Hz on both models

What actually changed in the Sub 4

The differences are all in the electronics, connectivity, and construction — the parts around the drivers, not the drivers themselves:

• Processing power and memory: the Sub 4 has a faster CPU and more memory, which Sonos positions as headroom for future software features and more stable integration with newer speakers like the Arc Ultra.
• Wi-Fi 6 radio: the Gen 3 uses 802.11a/b/g/n Wi-Fi; the Sub 4 moves to Wi-Fi 6. This doesn’t make bass better — it makes the wireless link more resilient in congested networks.
• Up to 50% lower idle power: per Sonos, and it uses fewer materials overall.
• Matte finish: the Gen 3’s high-gloss cabinet (a fingerprint magnet) is replaced by a soft-touch matte finish in black or white, matching the Sub Mini.
• Lighter build: 11.79 kg for the Sub 4 versus 16 kg for the Gen 3, per Sonos’s comparison specs — a real difference if you’ll be lifting, repositioning, or shipping it. Dimensions (389 × 402 × 158 mm) and upright-or-horizontal placement are otherwise unchanged.

Notice what’s not on that list: drivers, amps, ported cabinet, 25 Hz floor. Sonos made no claims about louder, deeper, or tighter bass — because the hardware producing it didn’t change.

Spec table: Sub 4 vs Sub Gen 3 side by side

Specs from sonos.com product pages. Sonos publishes no wattage figures or chip details — anyone quoting them is guessing.

Sound: why the bass is effectively the same — and why that’s the honest answer

This is the section where weaker comparisons invent differences. We won’t. The drivers, amps, cabinet, and 25 Hz floor are shared, which means the output capability is shared. The Sub 4’s upgrades — processing, Wi-Fi 6, idle power, matte finish — are real improvements to the product, not the sound.

That tracks with what owners and reviewers report: community consensus is that there is no audible difference, and the professional reviews that stay honest (including AppleInsider’s verdict that the Sub 4 is “not something you’d upgrade to from the Sub 3”) say the same. Any audible difference in a side-by-side test would come from room placement, Trueplay calibration state, or expectation bias — not from the hardware.

One nuance worth stating plainly: neither sub works standalone. Both are system speakers that pair with a Sonos soundbar or supported speakers over your home Wi-Fi — no Bluetooth subwoofer mode, no line-in. If you’re building around non-Sonos gear, neither of these is your sub.

Should Sub Gen 3 owners upgrade?

Almost never. Since the acoustic hardware is identical, upgrading means paying full price for Wi-Fi 6, a matte finish, and a faster processor you’ll never hear. Your Gen 3 continues to receive software updates and works with every current soundbar from the Ray up to the Arc Ultra. There is no sonic scenario where the swap is worth the money.

The exceptions are narrow enough to list:

• Your Wi-Fi is a war zone and your sub drops out. If you live in a dense apartment building with congested airwaves and your Gen 3 intermittently loses connection (dropping bass or lagging multi-room sync), the Sub 4’s Wi-Fi 6 radio is a genuine connectivity upgrade. Before buying anything, though, run the Sonos Doctor diagnostic — most bass dropouts are network or placement problems, not generation problems.
• Your Gen 3 is failing out of warranty. Replacing a dead sub is a new purchase, not an upgrade — and then the Sub 4 is the right new purchase.

Everyone else: keep the Gen 3. The smart money for existing owners isn’t an upgrade — it’s a second sub, covered next.

Buying new today: the value math

For new buyers, this is a pricing decision disguised as a product decision. The bass is the same, so what you’re really choosing is how much the Sub 4’s newer electronics, Wi-Fi 6, and matte finish are worth to you relative to the price gap.

The price-gap framework

Street prices move constantly, so check live pricing before deciding — but the logic is stable. Work through it like this:

1. Start with the Sub 4’s price as your baseline. It’s the current generation; it’s the default choice when prices are close.
2. Find a certified refurbished Gen 3 and note the discount. Sonos runs a Certified Refurbished program — refurbished Subs go through full factory testing and carry the same one-year warranty as a new unit, with all accessories included. This is the safest way to buy a previous generation.
3. Ask one question: is the saving worth the generation gap? The gap buys you Wi-Fi 6, lower idle power, matte finish, a faster processor, lighter build, and a longer expected support runway. If the refurb Gen 3 saves you a meaningful chunk of the Sub 4’s price — money you’d actually feel — the Gen 3 is the rational buy. The bass is the same, and the warranty is the same.

Put it more bluntly as a rule of thumb: a certified refurb Gen 3 at a clear discount is the best value subwoofer Sonos sells for medium and large rooms, because every dollar of the discount is savings on things you can’t hear. Buy the Sub 4 when the discount isn’t there to take.

What not to do: pay full price for a used Gen 3 from a stranger when a certified refurb with a warranty costs roughly the same. Refurb-from-Sonos beats used-from-marketplace on risk-adjusted price almost every time. [AFFILIATE LINK: Sonos Certified Refurbished Sub]

The dual-sub angle: Gen 3 + Sub 4 pair together

Here’s the section nobody else covers properly, and it’s the most interesting one. Sonos officially supports mixing Sub generations in a dual-sub setup. A Sub Gen 3 and a Sub 4 can be paired together in one home theater system, and the dual-sub configuration is supported with the Arc Ultra and Arc (“pair two with Arc Ultra or Arc”). The one exclusion: a Gen 2 Sub can’t be combined with a Gen 4 in a dual setup — you need Gen 3 and/or Sub 4 for the pair.

Why does this matter for your wallet? Because it removes the biggest cost trap in upgrading:

• Already own a Gen 3? Don’t sell it and rebuy to get dual subs. Add a second Gen 3 (refurbished is fine) or a Sub 4 — they work together, and mixed-gen dual-sub is officially supported, not a hack.
• Buying your first flagship sub? The cheapest path to dual subs later is a refurbished Gen 3 now plus a Sub 4 (or another refurb Gen 3) when budget allows. No “wrong generation” penalty — your first sub never becomes a paperweight.
• Why go dual at all? Two subs smooth out room modes — bass nulls and peaks that a single sub can’t fix no matter where you place it. In larger or oddly shaped rooms, a second sub delivers more even bass across seats than any single-sub upgrade.

If you’re planning a big room around the Arc Ultra with two subs, that’s the one setup where buying two Sub 4s new makes sense — but buying your first sub as a refurb Gen 3 now keeps the dual-sub door open for later at a fraction of the entry cost. [AFFILIATE LINK: Sonos Sub 4 (second sub for dual setup)]

Pairing with your soundbar: Arc Ultra, Arc, Beam, and beyond

Both generations pair with the same modern lineup: Arc Ultra, Arc, Beam (Gen 1 and Gen 2), and Ray, plus music-first setups with the Five, Era 300, or Era 100. The one compatibility difference worth knowing runs in the old direction: the Sub 4 does not support the Playbar and Playbase (Sonos’s long-discontinued soundbars), while the Gen 3 still pairs with them. If you’re running a Playbar-based system and want to keep it, the Gen 3 is your only flagship option — though at that point, you’re keeping a legacy soundbar alive with a legacy sub, and planning the eventual move to a current soundbar is the real project.

A few pairing notes by soundbar:

• Arc Ultra: the natural partner for a new Sub 4 — it’s the pairing Sonos launched them together for, and the headline dual-sub setup. An Arc Ultra with a single Gen 3 sounds identical to one with a single Sub 4, though.
• Arc: supports dual subs too. If you’re buying an Arc second-hand (a common deal), a refurb Gen 3 is the value-consistent sub choice.
• Beam (Gen 2) and Ray: both flagship subs are arguably more sub than these smaller soundbars need — check Sub Mini vs Sub 4 before defaulting to the flagship.

Cross-link for the soundbar side of the decision: our Arc vs Beam Gen 2 decision guide.

Which one should you buy? — three-scenario decision framework

And one forward-looking scenario: if a dual-sub Arc Ultra setup is your 12–18-month plan, don’t agonize over which generation your first sub is — buy the cheap certified unit now (Gen 3 refurb) and add whatever’s available later. Mixed-gen pairing is officially supported, so your first sub is never stranded.

FAQ

Does the Gen 3’s NFC setup matter?

No. The Gen 3’s NFC touch zone just hands your phone’s Wi-Fi credentials to the Sonos app during setup — a small convenience. Both subs ultimately join your system through the app, and the Sub 4 uses the app-only flow. Don’t let NFC decide anything.

Do both support Trueplay?

Yes. Crucially, re-run Trueplay after any change — adding a sub, moving it, or adding a second sub. A fresh tune does more for your bass than any generation swap.

How long will the Gen 3 keep getting software updates?

Sonos hasn’t announced an end of support for the Gen 3, and it continues to receive updates alongside current products. Sonos doesn’t publish update lifetimes in advance, so we can’t promise a date. The Sub 4’s newer processor gives it more headroom for future features — one of the real (if unquantifiable) reasons to prefer it when prices are close.

Weight and dimensions — does 16 kg vs 11.79 kg matter for placement?

Both are 389 × 402 × 158 mm and can stand upright or lie on their side (including tucked under a sofa). The weight difference matters when you’re moving the sub — lifting it, repositioning it, or shipping it — not when it’s sitting still. Once placed, both are heavy enough not to walk across the floor, which is the point of the weight.

Can I use a Sub Mini with a Gen 3 or Sub 4 as a dual pair?

No. Dual-sub setups require two full-size subs — Gen 3 and/or Sub 4. The Sub Mini can’t be paired as a second sub alongside a full-size unit (one Mini per system). If your room is small enough for the Mini question, see our Sub Mini vs Sub 4 comparison.

My bass keeps dropping out — is that a Gen 3 problem?

Probably not a generation problem. Bass dropouts are usually network congestion, interference, or placement — run the Sonos Doctor diagnostic before spending money. The Sub 4’s Wi-Fi 6 radio only matters if you genuinely live in a Wi-Fi war zone; treat it as a last resort. Related: our TV Audio Swap guide and Era 100 vs Era 300 as surrounds.