In this review, we will be comparing RTi A1 and R-51M, two Passive Bookshelf speakers from Polk Audio and Klipsch. Let's have a brief look at the main features
of Polk RTi A1 and Klipsch R-51M first before getting into our more
detailed comparison.
Polk RTi A1 Key Specs
- 2-way Design
- 1" Dome Tweeter
- 5.25" Polymer composite Woofer
- 60-26k Hz Frequency Response
- 89 dB Sensitivity
- Impedance: 8ohms
- Power Range:20-125watts
- Weight:5.44kg
- Dimensions (H x W x D): 304.8" x 7.3" x 11.5"( 304.8 x 187.5 x 292.1mm )
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 )
What size room are the Polk RTi A1 and Klipsch R-51M 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 RTi A1 |
Klipsch R-51M |
| 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.)
In the following sections, we will get into more detail in order to better understand how the Polk RTi A1 and Klipsch R-51M 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 RTi A1 and R-51M are 2-way speakers.
| Driver |
Polk RTi A1 |
Klipsch R-51M |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5.25-inch
|
1 x 5.25-inch
|
RTi A1 features a 1" silk polymer composite Dome Tweeter and 1 x 5.25" Polymer composite Woofer with a Crossover frequency at 1900Hz. On the other hand, the R-51M features a 1" Tractrix Horn Tweeter and 1 x 5.25" Copper-spun IMG Woofer with a Crossover frequency at 1660Hz.
Frequency Response
RTi A1 has a frequency range of 60-26k Hz whereas R-51M has a frequency range of 62-21k Hz. With a minimum frequency of 60Hz, the RTi A1 can go slightly deeper then the R-51M's min frequency of 62Hz.
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
RTi A1 and R-51M have the same Impedance of 8 ohms but where they differ is the sensitivity levels. RTi A1 sensitivity is rated at 89 dB and the R-51M's is at 93 dB. This 4 dB difference makes the Klipsch R-51M a more sensitive speaker compared to Polk RTi A1, 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.
RTi A1 can handle a max power of 125 watts RMS from the amp the whereas R-51M has a max power handling value of 85 watts RMS, 40 watts less than the RTi A1.
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
RTi A1 features Pair of Dual 5-way Binding Posts - Gold-Plated posts which make bi-amping or bi-wiring possible. R-51M has a Single Gold Plated Binding Posts - 5-way which doesn't feature bi-amping/bi-wiring.
Klipsch R-51M's Single Gold Plated Binding Posts - 5-way terminals
Cabinet Type and Port Position
RTi A1 has a back and front firing port whereas R-51M has a rear firing ports.
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 RTi A1's and Klipsch R-51M's external dimensions. Polk RTi A1 has external dimensions of 304.8 x 187.5 x 292.1mm ( 12.0 x 7.3 x 11.5inch) whereas Klipsch R-51M has external dimensions of 338.0 x 178.0 x 215.0mm ( 13.3 x 7.0 x 8.4inch) .
Klipsch R-51M is 9.5mm narrower and 77.1mm less deeper than Polk RTi A1 but it is also 33.2mm taller.
Below you can see the front view size comparison of Polk RTi A1 and Klipsch R-51M in scale.
Comparison image of Polk RTi A1 and Klipsch R-51M Size and External Dimensions
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 RTi A1 is approximately 547.7cm2 / 84.9inch2 and base area of the Klipsch R-51M is approximately 382.7cm2 / 59.3inch2. The RTi A1 requires 43% more surface area than the R-51M which gives it a small disadvantage on placement in tight spaces.
Here is an another comparison that shows both speakers on a BDI Octave Media Cabinet, next to a standard size amplifier and turntable in scale:
Size Comparison image of Polk RTi A1 and Klipsch R-51M on a Media Console
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 RTi A1 weighs 5.44kg / 12lbs and the Klipsch R-51M weighs 5.00kg / 11lbs. This makes the RTi A1 9% heavier than the R-51M.
Here is a comparison of how RTi A1 and R-51M'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 RTi A1?
Here are the items that are included inside the box of RTi A1:
2 Cherry bookshelf speakers 2 Self-tapping screws 8 Self-adhesive rubber feet Owner's Manual Template Online registration sheet Polk Audio product brochure
What's in the Box of Klipsch R-51M?
Here are the items that come with the R-51M:
2 Bookshelf loudspeakers 2 Grilles (installed) 8 Self-adhesive rubber feet Quick Setup Guide Important Safety Instructions Warranty Information