In this review, we will be comparing two different type of speakers by Polk Audio. Polk Audio Signature S15 is a Bookshelf speaker whereas the S55 is a Floor-standing speaker.
Let's have a brief look at the main features
of Polk S15 and Polk S55 first before getting into our more
detailed comparison.
Polk S15 Key Specs
- 2-way Design
- 1" Dome Tweeter
- 5.25" Mica-reinforced polypropylene Woofer
- 50-40k Hz Frequency Response
- 88 dB Sensitivity
- Impedance: 8ohms
- Power Range:20-100watts
- Weight:5.90kg
- Dimensions (H x W x D): 304.8" x 7.4" x 10.2"( 304.8 x 190.0 x 260.4mm )
Polk S55 Key Specs
- 2-way Design
- 1" Dome Tweeter
- 2 x 6.5" Mica-reinforced polypropylene Woofer
- 32-40k Hz Frequency Response
- 90 dB Sensitivity
- Impedance: 8ohms
- Power Range:20-200watts
- Weight:20.00kg
- Dimensions (H x W x D): 1056.0" x 11-3/4" x 12-3/8"( 1056.0 x 299.0 x 315.0mm )
S15 and S55 are members of Polk Audio's Signature S series of speakers. Below you can find the loudspeakers from this series.
What size room are the Polk S15 and Polk S55 speakers good for?
The size of the room in which you are planning to use these loudspeakers is an important decision factor. Here we have compared their suitability to various sizes of environments considering their size and max power parameters:
| Listening Environment* |
Polk S15 |
Polk S55 |
| Near-field |
Average |
Bad |
| Small Room |
Good |
Poor |
| Mid-size Room |
Average |
Good |
| Large Room |
Poor |
Good |
| Very Large Room |
Bad |
Poor |
(* Approximate Room sizes: Small < 100sq. ft / 9 m2, Mid-size: 100-220 sq. ft / 9-20 m2, Large 220-400 sq. ft / 20-36 m2, Very Large: > 400 sq. ft / 36 m2.
Average Floor Height: 9" / 2.7m. Typical room sizes differ from country to country, and the actual listening experience changes depending on floor height, room shape, surface materials, listening position, speaker locations, etc.)
In the following sections, we will get into more detail in order to better understand how the Polk S15 and Polk S55 compare and hopefully end up with enough arguments to decide which one of these loudspeakers is the better choice for you.
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Drivers
Both S15 and S55 are 2-way speakers.
| Driver |
Polk S15 |
Polk S55 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5.25-inch
|
2 x 6.5-inch
|
S15 features a 1" Terylene Dome Tweeter and 1 x 5.25" Mica-reinforced polypropylene Woofer with a Crossover frequency at 2500Hz. On the other hand, the S55 features a 1" Terylene Dome Tweeter and 2 x 6.5" Mica-reinforced polypropylene Woofer with a Crossover frequency at 2500Hz.
Frequency Response
S15 has a frequency range of 50-40k Hz whereas S55 has a frequency range of 32-40k Hz. With a minimum frequency of 32Hz, the S55 can go significantly deeper on the low side and provide stronger bass compared to the S15's min frequency of 50Hz.
Below graphs depict how these two speakers compare with the max, min and average values of the Min and Max Frequencies of other speakers in the Bookshelf class in our database.
Low Frequency
Bookshelf Speakers
High Frequency
Bookshelf Speakers
None of these speakers achieves full range experience which is commonly agreed as 20Hz-20kHz. In order to achieve lower lows / deeper bass, we recommend you pair these with a subwoofer. Visit our Powered Subwoofers section to find out more about the available options.
Impedance and Sensitivity
S15 and S55 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. S15 sensitivity is rated at 88 dB and the S55's is at 90 dB. This 2 dB difference makes the Polk S55 a more sensitive speaker compared to Polk S15, hence will play louder with the same amount of watts.
Sensitivity
Bookshelf Speakers
Power Range
Power
range is the range of input power in watts RMS that a loudspeaker is designed to handle. While using an amplifier within this range ensures the nominal performance , inputting a power that is higher than the max wattage can result in a damaged speaker.
S15 can handle a max power of 200 watts RMS from the amp the whereas S15 has a max power handling value of 100 watts RMS , 100 watts less than the S55.
Keep in mind that a higher max power handling value doesn't necessarily make that a louder speaker
compared to a lower max handling speaker. Loudness or the sound level is also impacted by parameters
such as Impedance, sensitivity and system efficiencies.
Input Type and Bi-Amping / Bi-Wiring
S55 features 5-way post posts which make bi-amping or bi-wiring possible. S15 has a Pair of Binding Posts - Gold Plated which doesn't feature bi-amping/bi-wiring.
Polk S55's 5-way post terminals allows Bi-amping or bi-wiring
Cabinet Type and Port Position
S15 has a rear firing port whereas S55 has a bottom firing ports. Polk S55's bottom-firing port gives more flexibility in placement in regards to proximity to walls compared to Polk S15 with its rear-firing port.
Polk S55 Port
Physical Specs
Size of a speaker can sometimes become an important decision factor due to space constraints or in some cases purely for esthetic reasons. In this section, we are going to compare Polk S15's and Polk S55's external dimensions. Polk S15 has external dimensions of 304.8 x 190.0 x 260.4mm ( 12.0 x 7.4 x 10.2inch) whereas Polk S55 has external dimensions of 1056.0 x 299.0 x 315.0mm ( 41-9/16 x 11-3/4 x 12-3/8inch) .
Polk S55 is clearly the larger of the two speakers. Its body is 109mm wider, 751.2mm taller and 54.6mm deeper than Polk S15.
Base Surface Area Comparison
Base surface area of a loudspeaker may become a determining factor when the space in your room or desk is limited.
The base surface area of the Polk S15 is approximately 494.8cm2 / 76.7inch2 and base area of the Polk S55 is approximately 941.9cm2 / 146.0inch2. The S15 requires 47% less surface area than the S55 which gives it a small advantage on placement in tight spaces.
What's in the Box of Polk S15?
Here are the items that are included inside the box of S15:
2 Bookshelf loudspeakers2 Grille (attached)8 Self-adhesive rubber feetWall-mount templateOwners ManualOnline Product Registration
What's in the Box of Polk S55?
Here are the items that come with the S55:
Floorstanding loudspeakerGrille (attached)4 Feet (pre-installed)Owners ManualOnline Product Registration
Mounting Bracket 
Height 
Base Surface Area 
Price per pair* 
Max Input Power 
Sensitivity 
Woofer Size 
Bi-Amping and Bi-Wiring