Immersive audio standard Dolby Atmos had a fairly inauspicious start when it came to soundbars, with speakers such as the Yamaha YSP-5600 being both crazy expensive ($1.5K or more) and "extraordinarily huge." But in the following years, with the help of companies like Vizio, the size of the products and the wallets needed to fund them became more manageable. Now, with the Polk Signa S4, you can buy a true, Atmos-capable system for half the price of a compatible AV receiver. And it's fairly compact, too.
- Energetic sound quality with movies and music
- Dedicated Dolby Atmos height channels
- Highly configurable sound modes
- No Wi-Fi
- Unable to adjust volume of heights
- Lacks surround capabilities
Dolby Atmos soundbars are designed to add the dimension of height, which makes them great for action movies and video gaming. What distinguishes the Atmos-toting Polk Signa S4 from other $400-plus soundbars is its physical upfiring speakers (competitors such as the Sonos Beam Gen 2 use psychoacoustics to mimic height effects). The Polk sounds good with music, too, and Atmos movies are really given a chance to shine.
The Polk Signa S4 does have some shortfalls, however. It's not possible to adjust the levels of the channels, or the height of the speakers, and the cheaper Signa S3 offers Wi-Fi connectivity, making it a better fit for music lovers. If you can stretch your budget a little further, the Vizio M512a offers even better sound, as well as dedicated surround channels for true immersion.
But if you want the best possible Dolby Atmos performance for the least amount of money, the Polk Audio Signa S4 is the soundbar to get.
Design and features
The Polk Signa S4 is a Dolby Atmos soundbar, featuring 3.1.2-channels of playback (left, right, center, front overheads and a wireless subwoofer). It offers a number of connection options and an array of useful sound modes.
In terms of competition, there are a couple comparable soundbars with either simulated or physical Dolby Atmos -- the Sonos Beam and the LG Eclair, respectively. Though the Eclair was briefly on sale for $400 while writing this review, it has since returned to the more prohibitive $600. For $100 more than the Polk, you can get the Vizio M512a, which comes with surround speakers.
Connections on the Polk run to a single HDMI eARC, digital optical and an analog 3.5mm input. While the Signa S3 comes with Wi-Fi and Google Chromecast built-in, the newer Signa S4 is Bluetooth only. If you want the option of asking Google to play a song on a compatible audio device, the Signa S3 (or even the MagniFi Mini) is the better way to go. Lastly, in the absence of networking, there's a USB-A port for any future firmware updates.
One standout feature of previous Polk soundbars has been its sound modes: Movie, Music, Night and, especially, Voice Adjust. The latter mode enables three separate levels of adjustment which brings it up against Zvox -- a company that also offers a number of configurable, hearing-enhancing modes. The main downside with this soundbar is that you can't adjust the levels of any of the channels, bar the sub. If you have tall or vaulted ceilings, for example, you may not be able to hear the overheads at all, which is something other soundbars like the Vizio M512a let you fix.
While some models on the market allow you to add rears later, the Signa S4 does not. If rear channels are something you want, then you should look at the Polk React or MagniFi soundbars instead.
The Polk's clicker is just as friendly as previous versions, with large, easy-to-decipher buttons and the ability to tailor the amount of sound enhancement without dealing with menus.
How does it sound?
Polk's soundbars have consistently been great with music, and the Signa 4 certainly carries the torch for musical replay. And it's just as talented when it comes to films. Whether you're watching action movies in Dolby Atmos or enjoying a low-key drama, the Polk will deliver the goods.
I compared the Polk against three competitors: the LG Eclair, the Vizio M512a and the Sonos Beam Gen 2. There was only one clear loser in this group -- and that has as much to do with the price as it does with performance.
I started my testing with Mad Max: Fury Road, one of the best movies to showcase the capabilities of any Dolby Atmos system. Despite lacking surround channels, the Polk was able to fill CNET's listening room with the proper amount of post-apocalyptic ambience. The opening scene begins with disembodied voices, which are flung to the corners of the room on a good system. The Polk was definitely able to keep up with the rival LG Eclair (another soundbar which lacks rear speakers).
While the Sonos Beam may not have physical height drivers, you wouldn't know it when watching this scene. The sense of width and height with the Sonos was able to match the LG and the Polk.
It was only when switching to the Vizio M512a that the benefits of surround were instantly recognizable. Instead of a wall of sound, the Vizio created a true bubble around my listening position. For example, at one key mark, a girl's voice asks, "Where are you, Max?" On most soundbars, the dialogue comes from above the speakers at the height of the screen. But on any decent surround system, the voice appears directly above the viewer's head, as it does with the Vizio.
Next, I tried the non-Atmos movie The Matrix (Chapter 9). There, the LG Eclair did the better job of integrating the pulsing bass soundtrack. At times the bass was a little lost on the Polk, but the trade-off was that it offered more midrange, more zinging bullet effects and more "air" on the shouted command "Freeze" at the start of the scene.
Though the LG Eclair has been tuned for music by folks at the high-end company Meridian, it was eclipsed by the Polk for most of the tunes I listened to. Both devices come with dedicated music modes, but the Polk was able to communicate even the most delicate music, while the LG gave songs a bright, almost hard sheen.
For instance, with the acoustic ballad Naked As We Came by Iron and Wine, the LG mixed the basics up. While it's a simple song with just a finger-picked guitar and Sam Beam's breathy voice, the LG rendered the guitar distant, and Beam's vocals sounded overbearing. I had to turn the volume down. In comparison, the Polk had the balance right, with a well-formed central vocal and a slightly ambient, though present, backing guitar. The Polk fared better than the Vizio here too, as Sam Beam's voice sounded smeared on the surround-capable bar, even in music mode.
Moving to something a little more astringent, the Polk was able to find the party in the Sunnyboys song Alone With You. This '60s throwback features swirling guitars and a central tenor vocal, but it's the stirring guitar solo that appears at 1 minute, 16 seconds, which can throw off some systems. The Vizio offered a better vocal performance but was undone by the solos, as was the LG.
Soundbars offering more detail are fine, but if you have a music collection that's a little rough around the edges, some systems can make these songs difficult to listen to. The Polk is able to see the good in everything and comes out on top here.
Should you buy it?
If you want true Dolby Atmos that's also affordable, then the Polk Signa S4 is the cheapest I've seen so far. A low price doesn't mean lacking performance, though, because the Polk is as solid as the other speakers in the line, for music and movies alike.
The only "issues" with the Polk come down to how the soundbar fares against its competition. Soundbars with better specs can be had for just a little more. For instance, the Signa S4 lacks the Wi-Fi music capabilities of the Sonos Arc (let alone the Signa S3), and you can't tailor the levels of each channel as you can with the Vizio M512a.
What if you're trying to keep it in the family? If you're deciding between the Polk React and the Signa S4, for example, be aware that they are quite different. The React trades Atmos for Alexa while also ditching the subwoofer.
If you want a ready-to-go system that plugs into a TV and sounds great, the Signa S4 is definitely the one to choose. It doesn't include much in the way of streaming capabilities or expandability, but it'll give you sterling performance as soon as it's out of the box. And that's all you really need.