In this review, we will be comparing Q350 and S15, two Passive Bookshelf speakers from KEF and Polk Audio. Let's have a brief look at the main features
of KEF Q350 and Polk S15 first before getting into our more
detailed comparison.
What size room are the KEF Q350 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:
In the following sections, we will get into more detail in order to better understand how the KEF Q350 and Polk S15 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 Q350 and S15 are 2-way speakers.
Driver |
KEF Q350 |
Polk S15 |
Driver Setup
|
2-way
|
2-way
|
Tweeter
|
1-inch
|
1-inch
|
Midrange
|
- |
- |
Woofer
|
1 x 6.5-inch
|
1 x 5.25-inch
|
Q350 features a 1" vented aluminum Dome Tweeter and 1 x 6.5" Aluminum Woofer with a Crossover frequency at 2500Hz. 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
Q350 has a frequency range of 63-28k Hz whereas S15 has a frequency range of 50-40k Hz. With a minimum frequency of 50Hz, the S15 can go significantly deeper on the low side and provide stronger bass compared to the Q350's min frequency of 63Hz.
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
Q350 and S15 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. Q350 sensitivity is rated at 87 dB and the S15's is at 88 dB. This 1 dB difference makes the Polk S15 a more sensitive speaker compared to KEF Q350, 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.
Q350 can handle a max power of 120 watts RMS from the amp the whereas S15 has a max power handling value of 100 watts RMS, 20 watts less than the Q350.
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
Q350 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.
Cabinet Type and Port Position
Both Q350 and S15 have rear firing ports. Rear ported speakers generally need more room between the backside of the speaker and the wall compared to sealed and front/bottom ported speakers. Placing the speakers too close to the walls may cause the bass to sound boomy.
If you are limited in space and can't get the speakers away from the backwall, check our Speakers with Front Firing Ports page.
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 KEF Q350's and Polk S15's external dimensions. KEF Q350 has external dimensions of 358.0 x 210.0 x 306.0mm ( 14.0 x 8.2 x 12.0inch) whereas Polk S15 has external dimensions of 304.8 x 190.0 x 260.4mm ( 12.0 x 7.4 x 10.2inch) .
KEF Q350 is clearly the larger of the two speakers. Its body is 20mm wider, 53.2mm taller and 45.6mm 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 KEF Q350 is approximately 642.6cm2 / 99.6inch2 and base area of the Polk S15 is approximately 494.8cm2 / 76.7inch2. The Q350 requires 30% more surface area than the S15 which gives it a small disadvantage 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 KEF Q350 weighs 7.60kg / 16.7lbs and the Polk S15 weighs 5.90kg / 13lbs. This makes the Q350 29% heavier than the S15.
Here is a comparison of how Q350 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 KEF Q350?
Here are the items that are included inside the box of Q350:
2 Bookshelf loudspeakers 2 Foam port plugs 8 Self-adhesive rubber feet Owner's Manual Warranty Registration Card
What's in the Box of Polk S15?
Here are the items that come with the S15:
2 Bookshelf loudspeakers2 Grille (attached)8 Self-adhesive rubber feetWall-mount templateOwners ManualOnline Product Registration
Max Input Power |
120 watts
vs
100 watts
|
Handle more power from your amplifier |
Woofer Size |
6.5 inches
vs
5.25 inches
|
Larger woofer |
Sensitivity |
88 dB
vs
87 dB
|
Play louder with same amount of amplification power |
Low Frequency Response |
50 Hz
vs
63 Hz
|
Generates deeper bass |
High Frequency Response |
40k Hz
vs
28k Hz
|
Generates higher frequency |
Mounting Bracket |
Yes
vs
No
|
Allows mounting on walls |
Height |
304mm
vs
358mm
|
Easier to fit in smaller spaces |
Base Surface Area |
494cm2 (190x260mm)
vs
642cm2 (210x306mm)
|
Takes less floor space |
Price per pair* |
259USD
vs
750USD
|
costs less (*prices may change depending on the seller, location and time) |
General |
KEF Q350 |
Polk Audio Signature S15 |
Brand |
KEF |
Polk Audio |
Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
Power Range |
10-120 watts |
20-100 watts |
Sensitivity |
87 dB |
88 dB |
Impedance |
8 ohms |
8 ohms |
Impedance |
3.7 ohms |
n/a |
Frequency Response |
63-28k Hz |
50-40k Hz |
Drivers |
|
|
Woofer Quantity |
1 |
1 |
Woofer Size |
6.5" |
5.25" |
Woofer Composition |
Aluminum |
Mica-reinforced polypropylene |
Woofer Surround Material |
Rubber |
Butyl rubber |
Tweeter Size |
1" |
1" |
Tweeter Type |
Dome |
Dome |
Aimable Tweeter |
No |
No |
Midrange Driver |
No |
No |
Crossover Frequency |
2500Hz |
2500Hz |
Firing Direction |
rear |
rear |
Physical Specs |
|
|
Height |
358.0mm (14.1") |
304.8mm (12") |
Width |
210.0mm (8.3") |
190.0mm (7.5") |
Depth |
306.0mm (12") |
260.4mm (10.3") |
Weight |
7.60kg (16.7lbs) |
5.90kg (13lbs) |
Enclosure |
Bass Reflex |
Bass Reflex |
Finish |
MDF/Vinyl-wrapped |
Meddite MDF |
Available Colors |
Black, Walnut, White |
Black, Walnut, Brown Walnut |
Mounting Bracket |
No |
Keyhole |
Recommended Stand Height |
18-24" |
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 |