Bookshelf speakers have been an integral part of the home theater industry since Edgar Villchur and Henry Kloss invented them to have compact, high-fidelity speakers suitable for smaller apartments.
Many companies have tried their luck in the business, but only a few successfully manufactured high-quality bookshelf speakers for an affordable price and one of the best brands is Polk. Polk now offers two entry-level bookshelf speakers, the S15 and S20, both full-range speakers.
We understand that choosing which is better between the two will be difficult for you. Both speakers have similar features, so we will be making an in-depth comparison between the two speakers to help you make an easier decision.
Sound Quality
Polk S15
The Polk S15 is an entry-level bookshelf speaker under the Polk’s Signature Series, equipped with one 5.25″ midrange woofer and a 1″ tweeter.
Audio Specification of the Polk S15:
| Polk S15 | Specifications |
| Type | Passive |
| Driver | 1” Terylene Tweeter5.25” Polypropylene Woofer |
| Frequency Response | 50 Hz to 40 kHz |
| Impedance | 8 Ohms |
| Crossover | 2.5 kHz |
| Sensitivity | 88 dB |
| Recommended Amplifier Power | 20 to 100 W |
The Polk S15 uses a dynamic balance acoustic array technology that enables it to produce a full-range sound that is so clean and rich. The technology also reduces the effects of vibrations on the speaker. The technology used in the speaker enables it to perform to its fullest potential without having any issues.
A frequency range of 50 Hz up to 40 kHz is impressive for its price and purpose as a compact bookshelf speaker, but you should not expect it to work like a subwoofer that produces very low frequencies. However, The Polk S15 can still deliver great bass for a bookshelf speaker.
The tweeter used for the can deliver up to 40 kHz, which is outstanding, and it can produce clear and smooth high frequencies. Its midrange is where the Polk S15 stands out. It is clear and does not easily get distorted, even when used in higher volumes. The Polk S15 is often compared to the SSCS5 which you can read my comparison review here.
Overall, the Polk S15 is a great sounding bookshelf speaker, as its highs and mids are impressive, while its lows are pretty satisfactory for a compact speaker. It is also compatible with Dolby and DTS surround sound technologies, which is remarkable for its price.
Polk S20
The Polk S20 is another entry-level compact bookshelf speaker that Polk makes under the Signature Series, featuring a 6.5-inch mid-bass transducer and a 1-inch fabric dome tweeter.
Audio Specifications of the Polk S20:
| Polk S20 | Specifications |
| Type | Passive |
| Driver | 1” Terylene Tweeter56.5” Polypropylene Woofer |
| Frequency Response | 39 Hz to 40 kHz |
| Impedance | 8 Ohms |
| Crossover | 2.5 kHz |
| Sensitivity | 88 dB |
| Recommended Amplifier Power | 20 to 125 W |
The Polk S20 also uses the dynamic balance audio array technology as it tunes the tweeter and woofer for a better mid and high-frequency response. It also eliminates possible issues so that the speaker can perform to its full potential.
It has a frequency response of 39 Hz up to 40 kHz, which is better than what the Polk S15 can offer. The Polk S20 can perform better when it comes to lower frequencies is that it can go down up to 39 Hz, which is impressive for its size and offers excellent bass.
Aside from low frequencies, the Polk S20 also produces clean mid-range and detailed high frequencies. As a full-range bookshelf speaker, the Polk S20 is excellent for producing sound with clarity and minimal distortion.
Overall, the Polk S20 is an excellent option if you are looking for a compact bookshelf speaker with incredible lows and clear mids and highs. You can use the Polk S20 for watching movies or listening to music without any issues with its sound quality. The Polk S20 has one of the best sound qualities for an entry-level bookshelf speaker.
Build Quality
Polk S15
The Polk S15 is a compact bookshelf speaker with excellent build quality and durability, and you can expect it to last for a long time. It is also lightweight, but it is pretty stable for its size.
Build Specifications of the Polk S15:
| Polk S15 | Specifications |
| Dimensions | 19.1 x 30.5 x 26 cm (7.5 x 12 x 10.2”) |
| Weight | 5.9 kg (13.0 lb) |
| Cabinet Material | Medite MDF |
| Placement and Mounting Options | Keyhole |
The Polk S15’s cabinet is made of a non-resonant Medite medium fiberboard, an industry standard for speakers and durability. The speaker’s design can reduce vibrations, which will help eliminate sound coloration.
The dome tweeter of the Polk S15 is made of Terylene, which is a synthetic polyester fiber. The material used for the tweeter helps deliver detailed high frequencies, which is very helpful for reproducing vocal and instrumental music.
The Polk S15 also uses the “Power Port” technology, a design patented by Polk that helps the transition of the airflow from its port into the listening area smoothly. The speaker’s design eliminates turbulence and distortion, resulting in a deeper bass impact.
Its midrange driver comprises a mica-reinforced polypropylene cone, a butyl rubber surround, a ceramic motor structure, and a high-temperature Conex fiber spider. The materials used in creating the driver help it produce precise mid-range frequencies and give more durability and less distortion.
The Polk S15 is available in three finishes: white, walnut, and black. It also comes with removable magnetic grills to complete its impressive aesthetics. Leaving the drivers exposed also gives the Polk S15 a glossy look, so whether you use the grilles or not, the speaker still looks excellent.
Overall, the build quality of the Polk S15 is outstanding. The materials that were for its tweeter and woofer are also impressive. You can expect that the Polk S15 will be able to work for a long time. It is a good deal for the price you are paying for its build quality.
Polk S20
The Polk S20 is also a compact bookshelf speaker that is pretty durable and sturdy. It also has no stability issues, and you can rest assured that you can put it anywhere in your home without it falling.
Build Specifications of the Polk S20:
| Polk S20 | Specifications |
| Dimensions | 21.6 x 37.6 x 35 cm (8.5 x 14.8 x 13.8”) |
| Weight | 7.7 kg (17.0 lb) |
| Cabinet Material | Medite MDF |
| Placement and Mounting Options | Keyhole |
Similar to the Polk S15, the cabinet of the Polk S20 is also made from non-resonate MDF with extra bracings. It also has an acoustically inert design as it helps to eliminate the coloration of the sound produced by reducing the effects of unwanted vibrations.
Like the Polk S15, the Polk S20 also has a fabric dome tweeter made of Tyrelene and a dynamic balance mica-reinforced polypropylene woofer. The materials used for the tweeter and woofer are impressive as it takes the quality of the speaker to a whole new level.
The Polk S20 also implements the Power Port technology in its design to produce a better low-frequency response. As a result, the Polk S20 can go down up to 39 Hz, which is an excellent frequency response with its size. It gives a better low-frequency performance for the Polk S20 compared to the Polk S15.
The Polk S20 is also available in three different colors: white, black, and walnut. It also comes with a detachable magnetic grille. Whether you put it or not, the Polk S20 has a beautiful aesthetic that you will love.
Like the Polk S15, Amazon also gave an average score of 4.8 stars out of 5 stars for the quality of materials used in building the Polk S20.
Overall, the Polk S20 has an excellent build quality that can compete with any top-level bookshelf speakers. It looks like a steal for the price you will pay for its build quality and life expectancy.
Controls
Polk S15
As a passive speaker, the Polk S15 has minimal control options. The Polk S15 only has two gold-plated binding posts for you to connect the speaker to a power amplifier. It is typical to have binding posts as the only control option for a passive bookshelf speaker.
The Polk S15 also has a built-in passive crossover, an excellent feature for separating the different frequencies into the tweeter and the woofer. It also ensures the safety of the driver.
Overall, the control options of the Polk S15 are what you expect from a passive speaker, so for the price you are paying for the Polk S15’s control option, it is still worth it.
Polk S20
Like the Polk S15, the Polk S20 also has a limited control option, expected from any passive speaker. It has gold-plated 5-way binding posts, as it helps you have a secure connection to your power amplifier without losing its signal. It also has a built-in passive speaker that separates specific frequencies to the tweeter and woofer, resulting in a better sound.
There is really nothing to expect when it comes to the control option for a passive speaker except for durable binding posts and a built-in passive crossover, which the Polk S20 has both.
Price
Polk S15
The Polk S15 is an excellent option if you are looking for a compact bookshelf speaker. You will get a pair of fantastic bookshelf speakers that are great for home use for the price you are paying. Amazon gave an average score of 4.7 stars out of 5 stars as reviewers consider that purchasing a Polk S15 is an excellent investment.
It is really an excellent deal for the price you are paying for the Polk S15’s sound and build quality. You will not regret your purchase of a pair of these speakers.
Polk S20
For its price point, the Polk S20 is a great option if you are looking for bookshelf speakers that can produce excellent bass and clear mids and highs. Amazon gave an average score of 4.9 stars out of 5 stars as its reviewers thought that purchasing a Polk S20 would be an excellent investment.
The Polk S20 is one of the best-priced bookshelf speakers available on the market. For the price you will pay for its sound and build quality, it looks like you are buying it at a discounted price for its worth.
If budget is a concern, have a look at my Polk S10 vs S15 comparison here. The S10 doesn’t hold as many features, but it might offer a more minimalistic option for those interested.
Pros and Cons
Polk S15
Pros:
- Impressive audio quality
- Durable materials
- Beautiful aesthetics
- Compatible with Dolby and DTS surround sound technologies
- It has a built-in crossover
Cons:
- Limited low frequency response
- Not as powerful compared to other speakers
- Limited control features
Polk S20
Pros:
- Excellent bass reproduction
- High-quality full-range speaker
- Solid build quality
- High-quality drivers
- Compatible with Dolby and DTS
Cons:
- A little bit bigger for a compact-sized speaker
- Heavier than expected
- Limited connectivity options
Which Is Better?
The Polk S15 and S20 are excellent options for high-quality entry-level bookshelf speakers, but if I have to choose which is better, I have to go with the S20. Both speakers have similar features, but the S20 has a better frequency response, as it can go down up to 39 Hz, which the S15 cannot.
