Sonos Sub 4 Review: Powerful, flexible and expensive

Verdict

An iterative upgrade, the Sonos Sub 4 doesn’t make much sense for anyone with a previous-generation Sub. However, if you’ve got a large room or more robust system, such as an Arc Ultra, and want more bass, the Sub 4 is a powerful, smooth and well-balanced way of adding more oomph to your system.

Introduction

I couldn’t quite believe that the Sonos Sub 4 is the 4^th generation of the product. While other Sonos speakers have seen major changes, the Sub line gets more minor tweaks with each subsequent version.

Slightly lighter and a bit more powerful than the Sub 3, the new model remains a brilliant subwoofer, but there’s no clear reason to upgrade from an older model.

Design

• A rounded cube with two speakers that face each other
• Can stand up or lie flat
• Works with S2

I remember the original Sub launch way back in 2012. It was a revolutionary subwoofer at the time, with a design like no other. In fact, I’ve still got my original Gen 1 Sub, as it remains compatible with the S2 system.

The Sub 4, like the 2 and 3 before it, is more of a marginal tweak to the original, with pretty much the same design, although a new high price ($799 / £799). That’s a lot of money.

While the design hasn’t really changed, even after 12 years, the Sub still looks brilliant and is still different from most other subwoofers.

Our Sub 4 vs Sub 3 article goes into more detail about the differences between generations, but both products are about the same size. The new version is available in matt white or black, to match the line-up of speakers. That’s an improvement on the glossy finish of the Sub 3, which easily picked up fingerprints.

I find that the Sub is a nice height to put next to an AV cabinet, blending in well. However, as it’s a Sub, it doesn’t have to sit upright. In fact, as the manual says, the Sub 4 can be placed in a corner, against a wall, behind, under or next to any piece of furniture on any kind of floor surface. If you don’t want to see the Sub, you can hide it away, say sliding it underneath a sofa.

This flexibility all comes down to the way that the Sub 4 (and previous generations) are built, with two drivers facing each other to create a force-cancelling effect that prevents buzzes and rattles from being produced.

Features

• Doubles the memory
• Faster processor
• Trueplay tuning

It’s hard to tell from Sonos’ basic specs what the differences are in hardware between the Sonos Sub 4 and the previous model. Both have two Class-D amplifiers and two woofers; the Sub 4 is listed as having two 5-inch x 8-inch woofers.

The Sub 4 doubles memory to 512MB, has a faster processor (quad-core 4xA55 1.9GHz) and supports Wi-Fi 6 for more reliable networking. As with its predecessor, the new model will output sound down to 25Hz.

There’s also a difference in the supported products, and the main difference is in the products the Sub 4 is not compatible with. It won’t work with Play:1, Play:3, Play:5 (Gen 2), Connect:Amp, and Symfonisk (Gen 1) speakers, nor the Playbar and Playbase.

The Sub 4 is compatible with all new speakers, and it can be used with the Sonos Arc Ultra. The Arc Ultra supports two subwoofers, which can be two Sub 4, two Sub 3 or a mix of the two.

The mix could be handy if you’ve got a Sub 3 already and fancy going for a dual-sub setup with the new soundbar. This configuration does hint that the sound output between the Sub 3 and Sub 4 is very similar, as why would Sonos let you mix and match otherwise?

Like its predecessors, the Sub 4 is best paired with the more powerful speakers in the line-up, such as a Five or Era 300 (or a pair of each) and/or in larger rooms. For smaller rooms and smaller speakers, the Sub Mini makes more sense.

Installation of the Sub is easy, with the app quickly picking it up and adding it to your system, once you hit the Join button on the front. As it’s not a standalone product, the Sub 4 has to be added to an existing speaker or speaker set.

As Sonos knows the full audio specs of all of its products, it can tune its speakers, the Sub and the crossover automatically. That’s true of all products bar the Sonos Amp without Sonos Architectural speakers, where you have to manage the crossover yourself.

Trueplay tuning is also available and should be run to finetune the experience for your room. After that, there’s not much control in the app, with an option to adjust the Sub level or turn it off completely; the latter of which can be useful if you want to watch at night.

Sound Quality

• Powerful bass
• Neatly balanced audio

The Sub 4 is a very good sub: it’s loud and it’s powerful. More importantly, it is exceptionally well balanced. Bass shouldn’t jump out like a separate entity; it should be smoothly integrated into the soundscape, blending in, but adding that extra thump. This, the Sub 4 does brilliantly.

I started by using the Sub 4 with the Sonos Arc Ultra. In my Arc Ultra review, I said that you don’t necessarily need the Sub 4. That’s true: the new soundbar produces plenty of bass by itself. Adding the Sub 4 makes a subtle but noticeable difference.

Watch the start of The Acolyte (critically panned, maybe, but the bar fight sequence is genuinely good fun), and the sub adds warmth and depth to the lightsaber as it buzzes and swishes around.

The Sub 4 adds more impact, too. Watch the start of Indiana Jones and the Dial of Destiny with the soundbar, and the bomb crashes down impressively; add the Sub 4, and you feel the impact.

For those that want the best home cinema experience, a Sub 4 or even a pair really enhances the Sonos Arc Ultra, or, indeed, a single Sub 4 works well with the original Arc.

I also moved the Sub 4 to the room with my Five speakers. It’s a good speaker, but the Sub 4 adds warmth and detail to tracks. OK Go’s base-heavy This Too Will Pass makes the room shake, while Rage Against the Machine’s Bomb Track kicks into life and you feel the impact from the bass line before the guitars kick in.

The question is, is the Sub 4 really that much better than previous generations? That is hard to answer, and I didn’t find it noticeably better than the Sub 3, or even my trusty old original Sub 1. I certainly wouldn’t replace a perfectly good working Sub with the Sub 4; if buying new, then it’s a different story.

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