In this review, we will be comparing XT15 and S15, two Passive Bookshelf speakers by Polk Audio.
Let's have a brief look at the main features
of Polk XT15 and Polk S15 first before getting into our more
detailed comparison.
| Key Specs | Polk XT15 | Polk S15 |
|---|
| Brand | Polk Audio
United States · founded 1972 | Polk Audio
United States · founded 1972 |
|---|
| Design | 2-way | 2-way |
|---|
| Tweeter | 1" Soft-Dome | 1" Dome |
|---|
| Woofer | 5.25" Bi-laminate paper | 5.25" Mica-reinforced polypropylene |
|---|
| Frequency response | 48-40k Hz | 50-40k Hz |
|---|
| Sensitivity | 86 dB | 88 dB |
|---|
| Impedance | 8 ohms | 8 ohms |
|---|
| Power range | 30-150 watts | 20-100 watts |
|---|
| Weight | 4.09kg / 9lbs | 5.90kg / 13lbs |
|---|
| Dimensions (H x W x D) | 10-5/8" x 6-9/16" x 7-3/16"
270.0 x 167.0 x 183.0mm | 12.0" x 7.4" x 10.2"
304.8 x 190.0 x 260.4mm |
|---|
What size room are the Polk XT15 and Polk S15 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 XT15 |
Polk S15 |
| Near-field |
Poor |
Average |
| Small Room |
Average |
Good |
| Mid-size Room |
Good |
Average |
| Large Room |
Average |
Poor |
| Very Large Room |
Poor |
Bad |
(* 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.)
The sections below take each area in turn: drivers, frequency response, physical size and what you get in the box.
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through our links. As an Amazon Associate I earn from qualifying purchases.
Drivers
Both XT15 and S15 are 2-way speakers.
Polk XT15Polk S15
TweeterWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
Polk XT15 |
Polk S15 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5.25-inch
|
1 x 5.25-inch
|
XT15 features a 1" Soft-Dome Tweeter and 1 x 5.25" Bi-laminate paper Woofer. On the other hand, the S15 features a 1" Terylene Dome Tweeter and 1 x 5.25" Mica-reinforced polypropylene Woofer with a Crossover frequency at 2500Hz.
Frequency Response
XT15 has a frequency range of 48-40k Hz whereas S15 has a frequency range of 50-40k Hz. With a minimum frequency of 48Hz, the XT15 can go slightly deeper then the S15's min frequency of 50Hz.
The graph below depicts how these two speakers compare with the max, min and average Low Frequency values of other speakers in the Bookshelf class in our database.
Low Frequency
Bookshelf Speakers
Neither pair reaches down to 20Hz, the usual definition of full-range, which is normal for speakers of this size. If you want the bottom octave for movies or bass-heavy music, add a subwoofer to whichever you choose. Visit our Powered Subwoofers section to find out more about the available options.
Impedance and Sensitivity
XT15 and S15 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. XT15 sensitivity is rated at 86 dB and the S15's is at 88 dB. This 2 dB difference makes the Polk S15 a more sensitive speaker compared to Polk XT15, 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. Staying
within that range gives nominal performance; driving the speaker beyond its maximum wattage can damage it.
XT15 can handle a max power of 150 watts RMS, whereas S15 has a max power handling value of 100 watts RMS, 50 watts less than the XT15.
Note that higher power handling does not make a speaker louder: that depends mainly on
sensitivity and impedance. The calculator below shows how loud each of these actually plays
on a real amplifier.
Which plays louder on your amplifier?
Starting with a popular amplifier - change it to the one you own, or any you are
considering, and watch both numbers move.
Input Type and Bi-Amping / Bi-Wiring
XT15 features Pair of Binding Posts - Gold Plated type posts and S15 has a Pair of Binding Posts - Gold Plated type posts. None of these speakers feature bi-amping/bi-wiring.
Physical Specs
The size of a speaker can sometimes be 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 XT15's and Polk S15's external dimensions. Polk XT15 has external dimensions of 270.0 x 167.0 x 183.0mm (10-5/8 x 6-9/16 x 7-3/16inch) whereas Polk S15 has external dimensions of 304.8 x 190.0 x 260.4mm (12.0 x 7.4 x 10.2inch).
Polk S15 is clearly the larger of the two speakers. Its body is 23mm wider, 34.8mm taller and 77.4mm deeper than Polk XT15.
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 XT15 is approximately 305.6cm2 / 47.4inch2 and base area of the Polk S15 is approximately 494.8cm2 / 76.7inch2. The XT15 requires 38% less surface area than the S15 which gives it a small advantage on placement in tight spaces.
Weight Comparison The weight of a loudspeaker can become an important factor if you need to move and reposition the unit often. Weight of a speaker can also "sometimes" be an indicator of the rigidity of the enclosure and the quality of the internal components used. The Polk XT15 weighs 4.09kg / 9lbs and the Polk S15 weighs 5.90kg / 13lbs. This makes the S15 44% heavier than the XT15.
Here is a comparison of how XT15 and S15's weights compare with the average, max and min weights in Passive Bookshelf class.
Weight
All Bookshelf Speakers
What's in the Box of Polk XT15?
Here are the items that are included inside the box of XT15:
- 2 Bookshelf loudspeakers
- 2 Grilles (attached)
- 8 Self-adhesive rubber feet
- Owners Manual
- Online Product Registration
What's in the Box of Polk S15?
Here are the items that come with the S15:
- 2 Bookshelf loudspeakers
- 2 Grille (attached)
- 8 Self-adhesive rubber feet
- Wall-mount template
- Owners Manual
- Online Product Registration
 Max Input Power |
150 watts
vs
100 watts
|
Handle more power from your amplifier |
 Low Frequency Response |
48 Hz
vs
50 Hz
|
Generates deeper bass |
 Height |
270mm
vs
304mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
305cm2
vs
494cm2
|
Takes less floor space |
 Price per pair* |
199USD
vs
259USD
|
costs less (*prices may change depending on the seller, location and time) |
 Sensitivity |
88 dB
vs
86 dB
|
Play louder with same amount of amplification power |
 Mounting Bracket |
Yes
vs
No
|
Allows mounting on walls |
| General |
Polk Audio Monitor XT15 |
Polk Audio Signature S15 |
| Brand |
Polk Audio |
Polk Audio |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
30-150 watts |
20-100 watts |
| Sensitivity |
86 dB |
88 dB |
| Impedance |
8 ohms |
8 ohms |
| Frequency Response |
48-40k Hz |
50-40k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
5.25" |
5.25" |
| Woofer Composition |
Bi-laminate paper |
Mica-reinforced polypropylene |
| Woofer Surround Material |
Rubber |
Butyl rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
Soft-Dome |
Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
n/a |
2500Hz |
| Firing Direction |
n/a |
rear |
Physical Specs |
|
|
| Height |
270.0mm (10.6") |
304.8mm (12") |
| Width |
167.0mm (6.6") |
190.0mm (7.5") |
| Depth |
183.0mm (7.2") |
260.4mm (10.3") |
| Weight |
4.09kg (9lbs) |
5.90kg (13lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
MDF, Vinyl |
Meddite MDF |
| Available Colors |
Black |
Black, Walnut, Brown Walnut |
| Mounting Bracket |
No |
Keyhole |
| Recommended Stand Height |
28-32" |
24-30" |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
No |
No |
Other |
|
|
| Parts Warranty |
5 Years |
5 Years |
| Labor Warranty |
5 Years |
5 Years |
A generation apart: Polk XT15 is the newer design, against a 2016 model. Newer is not automatically better, but the older one is more likely to be discounted or near run-out.
| Area | Better | Why |
|---|
| Bass | evenly matched | Much the same reach (48Hz vs 50Hz). |
| Amplifier needs | B | Polk S15 is more sensitive (88dB vs 86dB), so it goes louder on the same amplifier. |
| Headroom | A | Polk XT15 takes more power (150W vs 100W) - more in hand in a big room. |
| Size | depends | Polk XT15 is easier to place; Polk S15 is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | depends | Neither adds bi-amping, a sub output or height drivers. Polk XT15 sits in a wider range (9 models), so a matched surround system is easier later. |
| Price | A | Polk XT15 is cheaper - $199 against $259, about 23% less. |
A Polk XT15 B Polk S15
depends neither is better in the abstract - it turns on your room, your system or how you will use them. Only specs published for both speakers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
Neither runs away with it - they trade advantages. Let the "depends" rows and your own room settle it. Match it to your room: we rate Polk XT15 the better fit for a mid-size room and a large room, and Polk S15 for near-field listening and a small room. In a large or open-plan room, Polk S15 has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, Polk XT15 is the easier speaker to get right.
And remember what a spec sheet cannot show: how each looks in your room and whether the finish suits it, what dealer support and warranty are like where you live, and how they actually sound to you. If you can hear them first - ideally with your own music - that will tell you more than any number above.