In this review, we will be comparing R-51M and S10, two Passive Bookshelf speakers from Klipsch and Polk Audio.
Let's have a brief look at the main features
of Klipsch R-51M and Polk S10 first before getting into our more
detailed comparison.
Klipsch R-51M Key Specs
- 2-way Design
- 1" Tractrix Horn Tweeter
- 5.25" Copper-spun IMG Woofer
- 62-21k Hz Frequency Response
- 93 dB Sensitivity
- Impedance: 8ohms
- Power Range:Up to 85watts
- Weight:5.00kg
- Dimensions (H x W x D): 338.0" x 7.0" x 8.4"( 338.0 x 178.0 x 215.0mm )
Polk S10 Key Specs
- 2-way Design
- 1" Soft-Dome Tweeter
- 4" Mica-reinforced polypropylene Woofer
- 67-40k Hz Frequency Response
- 87 dB Sensitivity
- Impedance: 8ohms
- Power Range:20-100watts
- Weight:2.73kg
- Dimensions (H x W x D): 214.0" x 5.0" x 6.1"( 214.0 x 127.0 x 155.0mm )
What size room are the Klipsch R-51M and Polk S10 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* |
Klipsch R-51M |
Polk S10 |
| Near-field |
Average |
Average |
| Small Room |
Good |
Good |
| Mid-size Room |
Average |
Average |
| Large Room |
Poor |
Poor |
| Very Large Room |
Bad |
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.)
In the following sections, we will get into more detail in order to better understand how the Klipsch R-51M and Polk S10 compare and hopefully end up with enough arguments to decide which one of these loudspeakers is the better choice for you.
**This post contains affiliate links, and I will be compensated if you make a purchase after clicking
through my links. As an Amazon Associate I earn from qualifying purchases.
Drivers
Both R-51M and S10 are 2-way speakers.
| Driver |
Klipsch R-51M |
Polk S10 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5.25-inch
|
1 x 4-inch
|
R-51M features a 1" Tractrix Horn Tweeter and 1 x 5.25" Copper-spun IMG Woofer with a Crossover frequency at 1660Hz. On the other hand, the S10 features a 1" Terylene Soft-Dome Tweeter and 1 x 4" Mica-reinforced polypropylene Woofer with a Crossover frequency at 2500Hz.
Frequency Response
R-51M has a frequency range of 62-21k Hz whereas S10 has a frequency range of 67-40k Hz. With a minimum frequency of 62Hz, the R-51M can go significantly deeper on the low side and provide stronger bass compared to the S10's min frequency of 67Hz.
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
R-51M and S10 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. R-51M sensitivity is rated at 93 dB and the S10's is at 87 dB. This 6 dB difference makes the Klipsch R-51M a more sensitive speaker compared to Polk S10, 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.
R-51M can handle a max power of 100 watts RMS from the amp the whereas R-51M has a max power handling value of 85 watts RMS , 15 watts less than the S10.
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
R-51M features 5-way post type posts and S10 has a 5-way post type posts. None of these speakers feature bi-amping/bi-wiring.
Klipsch R-51M's Single Gold Plated Binding Posts - 5-way terminals
Polk S10's 5-way post terminals
Cabinet Type and Port Position
Both R-51M and S10 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 Klipsch R-51M's and Polk S10's external dimensions. Klipsch R-51M has external dimensions of 338.0 x 178.0 x 215.0mm ( 13.3 x 7.0 x 8.4inch) whereas Polk S10 has external dimensions of 214.0 x 127.0 x 155.0mm ( 8.4 x 5.0 x 6.1inch) .
Klipsch R-51M is clearly the larger of the two speakers. Its body is 51mm wider, 124mm taller and 60mm deeper than Polk S10.
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 Klipsch R-51M is approximately 382.7cm2 / 59.3inch2 and base area of the Polk S10 is approximately 196.9cm2 / 30.5inch2. The R-51M requires 94% more surface area than the S10 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 Klipsch R-51M weighs 5.00kg / 11lbs and the Polk S10 weighs 2.73kg / 6lbs. This makes the R-51M 83% heavier than the S10.
Here is a comparison of how R-51M and S10's weights compare with the average, max and min weights in Passive Bookshelf class.
Weight
All Bookshelf Speakers
What's in the Box of Klipsch R-51M?
Here are the items that are included inside the box of R-51M:
2 Bookshelf loudspeakers 2 Grilles (installed) 8 Self-adhesive rubber feet Quick Setup Guide Important Safety Instructions Warranty Information
What's in the Box of Polk S10?
Here are the items that come with the S10:
2 Bookshelf loudspeakers2 Grille (attached)8 Self-adhesive rubber feetWall-mount templateOwners ManualOnline Product Registration
 Sensitivity |
93 dB
vs
87 dB
|
Play louder with same amount of amplification power |
 Woofer Size |
5.25 inches
vs
4 inches
|
Larger woofer |
|
Low Frequency Response |
62 Hz
vs
67 Hz
|
Generates deeper bass |
 Max Input Power |
100 watts
vs
85 watts
|
Handle more power from your amplifier |
 High Frequency Response |
40k Hz
vs
21k Hz
|
Generates higher frequency |
 Mounting Bracket |
Yes
vs
No
|
Allows mounting on walls |
 Height |
214mm
vs
338mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
196cm2
vs
382cm2
|
Takes less floor space |
| General |
Klipsch Reference R-51M |
Polk Audio Signature S10 |
| Brand |
Klipsch |
Polk Audio |
| Speaker Type |
Bookshelf speakers |
Satellite speakers |
| Power Range |
Up to 85 watts |
20-100 watts |
| Sensitivity |
93 dB |
87 dB |
| Impedance |
8 ohms |
8 ohms |
| Frequency Response |
62-21k Hz |
67-40k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
5.25" |
4" |
| Woofer Composition |
Copper-spun IMG |
Mica-reinforced polypropylene |
| Woofer Surround Material |
Rubber |
Butyl rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
Tractrix Horn |
Soft-Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
1660Hz |
2500Hz |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
338.0mm (13.3") |
214.0mm (8.4") |
| Width |
178.0mm (7") |
127.0mm (5") |
| Depth |
215.0mm (8.5") |
155.0mm (6.1") |
| Weight |
5.00kg (11lbs) |
2.73kg (6lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
MDF/Wood-grain vinyl |
Meddite MDF |
| Available Colors |
Black |
Black |
| Mounting Bracket |
No |
Keyhole |
| Recommended Stand Height |
24-28" |
28-31" |
| 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 |