Polk Audio Signa S4 Review (3.1.2 CH Dolby Atmos Soundbar)

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Polk Audio is no stranger when it comes to low cost, easy to use soundbars and their most famous series called “Signa” has reached its fourth generation showing how much success Polk Audio has enjoyed with this low cost offering of theirs. But while other manufacturers tend to make small upgrades over their previous low budget offerings the upgraded 4th generation Signa makes a bigger leap into Dolby Atmos territory. And so in our Polk Audio Signa S4 review today we will test this new release and if it is worthy of having the Dolby Atmos name on it.

Now since this is a low cost soundbar you may think that what Polk Audio did was what many other manufacturers have done with many of their low budget releases that also claim to be Dolby Atmos capable. Use virtual tech to create Atmos effects from simple 3.1 or even 2.1 channels systems. But here Polk Audio really surprised us, as for the first time in a Signa soundbar we actually get dedicated up-firing drivers that are responsible for the overhead layer. This is surely something we didn’t expect to be honest.

So let’s see real quick what the new Signa S4 has to offer. The S4 remains a soundbar-subwoofer combo as all previous iterations of it but now it utilizes a 3.1.2 channels configuration. This means it can decode Dolby Atmos sound along with all the older formats like Dolby Digital, Dolby Digital Plus and Dolby TrueHD. Once again we get Polk Audio’s Voice Adjust Technology, various sound modes and Bluetooth streaming but not much else.

In a way the Signa S4 seems like a very straightforward soundbar. Polk Audio upgraded its audio output but made sure to keep it simple enough making it a dream for casual users that want a taste of Dolby Atmos without having to drown under complicated settings and configuration options. Having a Dolby Atmos soundbar at a price of $399 will surely rise more than a few eyebrows. But can its performance make justice of its low price? Let’s find out…

Design, Inputs and Features

Exterior

When Polk Audio released the Signa S3 we noticed that the unit was very similar to the Signa S2 in terms of looks. But it seems that with the S4 they decided that a redesign was necessary in order to make the new release feel fresh and not more of the same with a new name slapped on it.

As such the new Signa S4 is completely redesigned and to be honest it looks more on par to something you would see in 2022. Its footprint has increased compared to previous generations and this probably has to do with the fact that more drivers had to be incorporated into the chassis. And while the new Signa S4 measures 41.2 x 3.7 x 2.4” (1046 x 95 x 60mm) its weight of just 6 lbs 6 oz (2.9 kg) makes it extremely easy to handle or even wall mount if you prefer that.

It’s height has also increased slightly but it still remains a low profile design that can fit under most TV models. But as a notice, since there are no IR repeaters, if your TV’s IR sensor is extremely low then it may obstruct the signal, so take appropriate measurements before pulling the trigger on this one.

Design wide the S4 features straight lines and curvy corners which gives it a simple but also modern look at the same time. The entire front and top sides are covered by a fabric cloth grille covering all the drivers while the rest of its body is made out of sturdy black colored plastic.

At the top we find a set of built-in control buttons located exactly at the middle including a power button, input selection, Bluetooth and volume controls. These buttons are physical ones and have good spacing in order not to accidentally press the wrong one in a dark environment.

One thing we always are very critical about when it comes to soundbars design is the kind of functions display they come with. Many manufacturers go for the usual full functions display but there are many low cost soundbars, and some not so low cost, that go a different route and this is to use an array of LED light indicators in order to show what the soundbar is doing. Unfortunately the entire Signa series was always using these LED lights and the Signa S4 seems to continue this trend.

Placed at the center of the front face exactly under the fabric grille there are five LEDs in a single row and depending the function of the unit different combinations and colors light up. This is the simplest way of a front display being used and to be honest it’s not a very practical one. Because if you don’t remember the combinations or the colors of the lights you will have to open the manual every single time to see what the unit is doing. Which is a bit frustrating and not so practical to do all the time.

At the back we get a limited number of connectors placed all together in a specially designed inset at the left while the power connector is kept isolated in another inset on the right. There are also special holes in order to wall mount it if you like and with its low weight this could not be any easier.

But it’s not only the main unit that Polk Audio decided to change as the subwoofer that is included also comes with a completely new design compared to the previous generations. It retains its cubic look but it borrows the same straight lines and curvy corners of the main unit in order to look similar when placed close together. And since the subwoofer is using a down-firing driver its chassis is stripped of any other details that could indicate its actual use and so at first it may look like a small table than an actual subwoofer.

The subwoofer sits on four long legs in order to leave enough space at the bottom for the driver to breathe while next to it we also find the air port, which is a rather unusual placement to be honest and one that we don’t usually see in subwoofers of this category. As for its size we measured it 7.9 x 12.9 x 11.0” (200 x 328 x 280mm) while its weight of 9 lbs 1 oz (4.1 kg) makes it actually lighter than its predecessors even though it comes with a bigger driver size than before.

Having reached its fourth generation it seems that Polk Audio deemed it necessary to go forward with a refreshed look and the new Signa S4 definitely looks good. It’s simple, nice and modern while build quality is what you should expect from a Polk Audio soundbar of this price.

Internal Hardware

If there is one area where the Signa S4 is completely overhauled over previous generations is in the channels configuration it utilizes. Polk Audio not only added Dolby Atmos but actually upped the number of channels to a full 3.1.2 channels system for the S4.

This means that not only they added an extra center channel that surely will help with the dialogue but the up-firing drivers will provide much better performance with Atmos effects compared to Dolby Atmos soundbars that use virtual tech in order to create the illusion of height activity.

The front fabric grille of the S4 is non removable but thankfully Polk Audio has provided exactly that they have used under the hood. As such for the two main channels we find two 4.7 x 1.6” (120mm x 40mm) racetrack mid drivers which are very commonly used in low profile units and are accompanied by a single 1″ (25mm) round tweeter for each channel that handles most of the upper frequencies. For the center channel a single 1” (25mm) round full range center driver is used while there are also two 2.6” (66mm) up-firing round Atmos drivers.

As for the subwoofer, this is also upgraded and now it comes with a single, down-firing 5.9″ (150mm) bass driver which is better than the previous smaller 5.25″ one used in the Signa S2 and S3.

Polk Audio does not provide any other details concerning the power output or frequency response so we have no means of comparing these to what other units offer.

The Signa S4 is a major upgrade over the previous releases in the series and looking at the specs we can confirm that this one is certainly on another level from its predecessors.

Connectivity

If there is one area where the S4 seems to be very similar to the previous releases is the connectivity ports available and looking at the back of the unit we find the exact same layout as previously seen in the other Signa units.

And so except from the included HDMI input we also get an AUX 3.5mm mini jack as well as a Digital Optical input with all of them being placed together in an inset on the left side of the soundbar as we look at it from behind. There is also a USB port that is placed right next to them but this seems to be used only for service as the soundbar doesn’t have any kind of USB streaming capabilities.

The only upgrade we find here is that the HDMI, for the first time in a Signa unit, supports eARC which means you can pass Dolby Atmos sound through the Dolby TrueHD container from a TV to the soundbar if your TV supports this. Keep in mind that Dolby Atmos can also be passed through the optical port but this is achievable only by using the Dolby Digital Plus container which requires less bandwidth and is very widely used in streaming services nowadays.

As for wireless capabilities the S4 retains its Bluetooth functionality which makes it possible to stream audio from your smartphone to the soundbar but on the other hand it looses WiFi that was available in the Signa S3. We have no idea why Polk Audio took out WiFi from the S4 but a possible reason is to keep the cost down and retain the unit’s simplicity and focus more on its Atmos performance.

If you really miss WiFi functionality then maybe the Signa S3 is the better option for you.

Control Options

Let’s see next how you can control the unit. We already mentioned above about the built-in buttons with which you can have some basic control over the Signa S4. But obviously the main way of control will be the included remote and the one that comes with the unit is very similar to the ones we had seen in previous Signa models.

The remote, although looks very similar, has also been redesigned and now it features more round buttons but without changing much of its layout or functionality. In general it is rather small making it easy to hold and push all buttons with one hand but its look certainly reflect the low cost nature of the soundbar itself. There are not many functions on the soundbar so the number of buttons needed are also very limited. On the top we get the power and mute buttons while under them there are three buttons in order to select desired input.

Two large buttons under them are for controlling the volume as well as the bass, next we get three buttons for the different modes you can select depending the content you watch like movies or music while a Night Mode is also available when you don’t want to bother other people while sleeping. Finally we get three buttons that adjust Polk Audio’s Voice Adjust Technology.

The buttons have the usual rubber feeling to them making them pleasant to the touch but the minus is that keeping with its cheap status there is no backlight functionality so using it in the dark can be a difficult thing to do.

There is also HDMI-CEC functionality. If your TV is connected via HDMI and your TV supports CEC (and it is enabled in the TV settings menu), you can control the volume and mute functions on Signa S4 from your TV remote without any further setup.

But even if you haven’t used the HDMI connection and you used optical, you may be able to control certain functions on the Signa S4 from your TV remote without any further setup if your TV is one of supported brands. Lastly if your TV is not supported the Signa S4 gives you the ability to teach your IR (infrared) remote to control volume, mute and other functions (such as source selection or bass volume) on your sound bar. Detailed instructions on how to do this are included in the manual and they are very easy to follow.

Unfortunately without WiFi the Signa S4 looses the ability to be controlled through voice commands and also there is no dedicated app that could be used instead. So don’t loose the remote as it’s your only means of controlling it.

Extra Features and Services

Looking at the feature set of the Signa S4 it was immediately apparent that Polk Audio wanted to keep this new release as simple to setup and easy to use as possible. So there are not many features or settings to go with overall.

But first of all let’s talk about the supported audio. The S4 can decode Dolby Digital, Dolby Digital Plus, Dolby TrueHD & Dolby Atmos signals both through the HDMI and Optical port with the latter only capable of a few of them due to bandwidth limitations. There is also Linear PCM support if your source device can support that.

Unfortunately for one more time there is no DTS in any form which is a shame even for a low cost soundbar as the Signa S4. There are many dirty cheap soundbars nowadays that support both Dolby Digital and DTS and this should be the case here also. So in case you want DTS support the Signa S4 is not for you.

Keeping similar characteristics from the previous Signa units the S4 comes with only some basic sound modes. You have the option to choose between Movie and Music mode depending on the kind of content you will use it for. But there is also a third one called Night mode which reduces bass and volume dynamics while improving voice intelligibility for low volume listening which can be very handy for late night use.

Polk Audio advertises a lot their Voice Adjust technology that was included in all the previous Signa soundbars and we find it here also providing three different levels of adjustment. Once again we tried the different levels and we believe the medium setting is the best one that combines enough dialogue clarity without overshadowing the rest of the audio too much.

The Signa S4 lacks any kind of EQ settings or an auto calibration system and the only adjustments that you can really make is the bass. From the remote you can control how much bass you like easy and fast with the press of a button. If you don’t like to go through various audio settings and calibrations then the Signa S4 is perfect in this regard. The Signa series was always very simple when it comes to sound modes and audio options and if you are the kind of person that doesn’t want to spend the time on these, this will be a great experience for you.

Lastly we should mention the unit’s streaming capabilities which, to be honest, are rather limited. With the included built-in Bluetooth you can stream audio from any Bluetooth enabled device. But the quality is certainly lower than what it would be if you stream music from a streaming service in your TV and through the HDMI connection. So while for casual use it may suffice if you want the best quality possible a wired connection is a must.

The soundbar is missing WiFi and so there are no online capabilities available. It can offer a purely offline experience. Also keep in mind that the Signa S4 cannot be expanded with surround speakers as many other models can do. So the 3.1.2 channels configuration is the best you can get out of it.

Initial Setup

The Signa series are famous for their simplicity and the S4 is no different. The whole process is so easy and fast that even if you have no previous experience you will have no trouble setting this up and be ready in just a few minutes.

The lack of many features and extra functions along with the very limited sound options makes the S4 an ideal option for all novice and casual users.

First of all you have to connect the Signa S4 to your TV either through the HDMI or the Digital Optical port, connect both the soundbar and subwoofer to a power outlet and turn them on. Now the soundbar and subwoofer are pre-paired from the factory but even if you have a connection problem a press of the button on the back of the subwoofer while also pressing the Bluetooth and VOL + on the remote will ensure the two will pair again. After that you just turn on the soundbar and you are ready to go. It couldn’t be more simple than that.

The Signa S4 is an excellent plug-and-play soundbar. If you are looking for more in-depth calibration options you are not going to find them with this one. It’s goal is to provide a good audio experience without the need to trouble yourself with any calibrations at all.

In terms of actual settings there are basically three buttons that you will need to press. Select the audio mode depending on the content, choose one of the three voice adjust settings and calibrate the bass volume. That’s all and it cannot be more straightforward that this one.

After all said and done we were ready for our movies testing.

Movies

With the Signa S4 utilizing up-firing Atmos drivers we were eager to put them to the test and see how they would perform. As such we decided to go with Independence Day: Resurgence in 4K UHD format which features an amazing Dolby Atmos mix.

One thing to keep in mind is that without any surround speakers all action was heavily front oriented. There was no behind-the-shoulder activity or even towards the sides. The soundbar is good at creating a front sound wall and we will talk about it shortly but the unit cannot envelope you in an immersion bubble. And the fact that you cannot expand the system to include surround speakers is something you have to keep in mind if you are thinking about cinematic surround sound.

Now since we got that out of the way we can say that what the Signa S4 can do at the front surprised us in a good way. Don’t forget that this is supposed to be a budget soundbar even if it is a step above its predecessors and the additional channels being utilized here are put in good use.

The soundstage at the front had good extension and nice depth and while the S4 is missing any kind of side-firing drivers you will hear sounds that extend beyond the physical limits of the unit itself. This sideways extension was not as evident as some other units that do come with side woofers but nevertheless you could feel the larger soundstage and sounds that originate further from the actual drivers.

Dialogue was very distinct and kept nicely at the center and here was saw a big improvement over the previous Signa models that didn’t have a center channel. During the most busy action scenes we never felt the need to up the Voice Adjust feature and all voices of the actors were isolated and never overlapped with the rest of the audio.

The most impressive aspect of the Signa S4 could not be other than its Atmos performance. Now, you shouldn’t expect to get the same kind of performance a dedicated Atmos system with height speakers can do but for a low cost soundbar this is the best you could expect for. There was definitely a sense of elevation and many sounds felt like coming above the TV at the middle between the screen and the ceiling, which by the way was around 9 feet high in our test room, giving a nice overhead extension to the performance.

Obviously all Atmos effects were front oriented as there were only two front channels available and you will be missing some precision and panning accuracy. Also we would say that the soundbar has a relatively narrow sweet spot where these effects are more prominent. Move out of the sweet spot and they loose most of their integrity and accuracy.

During the aerial combat scenes the Signa S4 reproduced some impressive panning sounds with fighter jets moving across the front channels showing that the system put all of its available channels in good use. In terms of audio quality the Movie mode felt like it was trying to create a wider front performance and it surely is the ideal one for such content. The Signa had satisfactory mid-range with a high end that had good energy and high resolution and a low end that was ok but missed the mark slightly as it could not be as vigorous and powerful as we would love to.

The subwoofer did add a certain low end depth and surely the soundbar did far better than other solutions that do not include one but again we felt the sub was a bit weak in performance. It could not offer the shaking experience that will keep you at the edge of your seat and even upping the bass a few notches on the remote did little to improve things. Ultimately changing this setting will not offer a much different outcome.

To be honest when we started testing the Signa S4 we had no idea what to expect. The Signa S3 was very close to the S2 but with the S4 offering a completely different experience we were pleasantly surprised that such a low budget offering can offer so good Atmos performance. Obviously you shouldn’t expect to be blown away by it but if you consider what the Signa S4 is then you will realize that it’s money well spent.

Music

Since the Signa S4 lacks both USB and online streaming we had two options. Either to use Bluetooth, which would certainly limit the quality of sound we would ultimately get or stream music through our TV using the HDMI connection which ensures the best quality we can get with this unit. At the end the second option was the best and this was the one we chose for our review.

One thing to keep in mind about the S4 is that there is no option for a true stereo sound performance. The Music mode does not change the active output channels so even with it all drivers are active. Although we do get that such a soundbar is meant for casual and novice users this is a fact that you should be aware of as there are some other brands that do offer stereo output with music.

So how the Signa can do with music? Well, we can say for certain that we had a very pleasant time with it. The S4 is very easy going and although it will not be your way into HiFi heaven it has a tonality and balanced output that was easy and relaxing to our ears.

Vocals had good clarity and energy without becoming bothering and even though we did use the unit for a few good hours not even once did we feel ear fatigue. Mid-range was good enough, all things considered, while the bass was once again a notch below expectations. It had good clarity, it kept the tempo nicely, it never felt boomy or muffled, it just didn’t have the power or low end depth that we would like to hear from it.

Stereo imaging was nice and there was good precision of all the sound sources. Clarity was missing a bit obviously but this again is not a HiFi system so we cannot ask for too much. We tried a few different genres and the S4 favored mostly those vocal based songs while some more heavy on the bass felt slightly flat although again for the casual user it will be just fine.

The Signa S4 may not have been designed with music in mind but it can surely do good enough with it too. Keep in mind that this is meant for casual use so if you know what to expect then its output and music performance will leave you satisfied for sure.

Final Thoughts

While the Signa S3 may had been a marginal update over the Signa S2, the Signa S4 seems to have made a bigger leap in terms of pure audio performance. Its low cost nature is still there so you shouldn’t expect to be suddenly blown off by its cinematic performance but the kind of upgrades Polk Audio did here were surely for the better.

On the plus side the added Atmos drivers add certain volume and height to the front sound performance and make the Atmos effects more detailed, precise and pronounced compared to Atmos soundbars that use only virtual technology to simulate them. Also one of the major strengths of the Signa family is simplicity both in terms of setup and ease of use and the Signa S4 continues this trend. And at a price of just $399 it is almost impossible to find another Dolby Atmos soundbar-subwoofer combo with dedicated Atmos drivers making the Signa S4 a real value for money choice.

On the other hand the soundbar, since it has no surround speakers, cannot create a fully immersive surround environment and the lack of expandability is not helping either. Also the subwoofer is not the most bombastic and powerful that could have been while there is no online functionality whatsoever. Sound options are at the most basic level with complete lack of any EQ settings while the LED indicators add more frustration than they should.

With the Polk Audio Signa S4 it seems that the design team decided to change their focus for its 4th generation release. Instead of creating a unit that would intergrade more in the online world they decide to throw all these out and instead focus in upping its core audio performance and Dolby Atmos experience. It surely keeps its simplicity that Signa units are famous of but as for everything else we believe this decision was in the right direction. If you are the kind of person that loves simplicity, don’t care about online functionality and seek the most cheap Dolby Atmos soundbar-subwoofer combo the Signa S4 should be at the top of your list.

For more reviews you can check our dedicated Soundbar-subwoofer combo reviews list or even look at our Product Reviews Table where you can find the brand and specific product you are looking for.

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