In this review, we will be comparing R-51M and RTi A3, 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 RTi A3 first before getting into our more
detailed comparison.
| Key Specs | Klipsch R-51M | Polk RTi A3 |
|---|
| Brand | Klipsch
United States · founded 1946 | Polk Audio
United States · founded 1972 |
|---|
| Design | 2-way | 2-way |
|---|
| Tweeter | 1" Tractrix Horn | 1" Dome |
|---|
| Woofer | 5.25" Copper-spun IMG | 6.5" Polymer composite |
|---|
| Frequency response | 62-21k Hz | 50-26k Hz |
|---|
| Sensitivity | 93 dB | 89 dB |
|---|
| Impedance | 8 ohms | 8 ohms |
|---|
| Power range | Up to 85 watts | 20-150 watts |
|---|
| Weight | 5.00kg / 11lbs | 7.26kg / 16lbs |
|---|
| Dimensions (H x W x D) | 13.3" x 7.0" x 8.4"
338.0 x 178.0 x 215.0mm | 14.7" x 8.4" x 14.0"
374.7 x 214.4 x 355.6mm |
|---|
What size room are the Klipsch R-51M and Polk RTi A3 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 RTi A3 |
| Near-field |
Average |
Poor |
| Small Room |
Good |
Average |
| Mid-size Room |
Average |
Good |
| Large Room |
Poor |
Average |
| 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.)
The sections below take each area in turn: drivers, frequency response, physical size and what you get in the box.
Drivers
Both R-51M and RTi A3 are 2-way speakers.
Klipsch R-51MPolk RTi A3
TweeterWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
Klipsch R-51M |
Polk RTi A3 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5.25-inch
|
1 x 6.5-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 RTi A3 features a 1" silk polymer composite Dome Tweeter and 1 x 6.5" Polymer composite Woofer with a Crossover frequency at 2800Hz.
Frequency Response
R-51M has a frequency range of 62-21k Hz whereas RTi A3 has a frequency range of 50-26k Hz. With a minimum frequency of 50Hz, the RTi A3 can go significantly deeper on the low side and provide stronger bass compared to the R-51M's min frequency of 62Hz.
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
R-51M and RTi A3 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 RTi A3's is at 89 dB. This 4 dB difference makes the Klipsch R-51M a more sensitive speaker compared to Polk RTi A3, 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.
RTi A3 can handle a max power of 150 watts RMS, whereas R-51M has a max power handling value of 85 watts RMS, 65 watts less than the RTi A3.
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
RTi A3 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
R-51M has a rear firing port whereas RTi A3 has a back and front firing ports.
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 Klipsch R-51M's and Polk RTi A3'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 RTi A3 has external dimensions of 374.7 x 214.4 x 355.6mm (14.7 x 8.4 x 14.0inch).
Polk RTi A3 is clearly the larger of the two speakers. Its body is 36.4mm wider, 36.7mm taller and 140.6mm deeper than Klipsch R-51M.
Below you can see the front view size comparison of Klipsch R-51M and Polk RTi A3 in scale.
Comparison image of Klipsch R-51M and Polk RTi A3 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 Klipsch R-51M is approximately 382.7cm2 / 59.3inch2 and base area of the Polk RTi A3 is approximately 762.4cm2 / 118.2inch2. The R-51M requires 50% less surface area than the RTi A3 which gives it a small advantage on placement in tight spaces.
Here is 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 Klipsch R-51M and Polk RTi A3 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 Klipsch R-51M weighs 5.00kg / 11lbs and the Polk RTi A3 weighs 7.26kg / 16lbs. This makes the RTi A3 45% heavier than the R-51M.
Here is a comparison of how R-51M and RTi A3'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 RTi A3?
Here are the items that come with the RTi A3:
- 2 Cherry bookshelf speakers
- 2 Self-tapping screws
- 8 Self-adhesive rubber feet
- Owner's Manual
- Template
- Online registration sheet
- Polk Audio product brochure
 Sensitivity |
93 dB
vs
89 dB
|
Play louder with same amount of amplification power |
 Height |
338mm
vs
374mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
382cm2
vs
762cm2
|
Takes less floor space |
 Price per pair* |
359USD
vs
465USD
|
costs less (*prices may change depending on the seller, location and time) |
 Max Input Power |
150 watts
vs
85 watts
|
Handle more power from your amplifier |
 Woofer Size |
6.5 inches
vs
5.25 inches
|
Larger woofer |
|
Low Frequency Response |
50 Hz
vs
62 Hz
|
Generates deeper bass |
 High Frequency Response |
26k Hz
vs
21k Hz
|
Generates higher frequency |
 Bi-Amping and Bi-Wiring |
Yes
vs
No
|
Allows bi-amping and bi-wiring connections |
 Mounting Bracket |
Yes
vs
No
|
Allows mounting on walls |
| General |
Klipsch Reference R-51M |
Polk Audio RTi A3 |
| Brand |
Klipsch |
Polk Audio |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
Up to 85 watts |
20-150 watts |
| Sensitivity |
93 dB |
89 dB |
| Impedance |
8 ohms |
8 ohms |
| Frequency Response |
62-21k Hz |
50-26k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
5.25" |
6.5" |
| Woofer Composition |
Copper-spun IMG |
Polymer composite |
| Woofer Surround Material |
Rubber |
Butyl rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
Tractrix Horn |
Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
1660Hz |
2800Hz |
| Firing Direction |
rear |
back and front |
Physical Specs |
|
|
| Height |
338.0mm (13.3") |
374.7mm (14.8") |
| Width |
178.0mm (7") |
214.4mm (8.4") |
| Depth |
215.0mm (8.5") |
355.6mm (14") |
| Weight |
5.00kg (11lbs) |
7.26kg (16lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
MDF/Wood-grain vinyl |
Real wood veneer |
| Available Colors |
Black |
Black, Cherry |
| Mounting Bracket |
No |
Keyhole |
| Recommended Stand Height |
24-28" |
24-31" |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
No |
Yes |
Other |
|
|
| Parts Warranty |
5 Years |
5 Years |
| Labor Warranty |
5 Years |
5 Years |
A generation apart: Klipsch R-51M is the newer design, against a 2008 model. Newer is not automatically better, but the older one is more likely to be discounted or near run-out.
| Area | Better | Why |
|---|
| Bass | B | Polk RTi A3 digs deeper - 50Hz against 62Hz. |
| Amplifier needs | A | Klipsch R-51M is more sensitive (93dB vs 89dB), so it goes louder on the same amplifier. |
| Headroom | B | Polk RTi A3 takes more power (150W vs 85W) - more in hand in a big room. |
| Size | depends | Klipsch R-51M is easier to place; Polk RTi A3 is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | B | Polk RTi A3: bi-amping. |
| Price | A | Klipsch R-51M is cheaper - $359 against $465, about 23% less. |
A Klipsch R-51M B Polk RTi A3
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?
The usual trade-off: Polk RTi A3 measures better, Klipsch R-51M costs about about 30% more% less. Whether that gap is worth the money is the call only you can make - and in a normal room it is often smaller than the numbers suggest. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 62Hz anyway, which makes the cheaper Klipsch R-51M much easier to justify. Match it to your room: we rate Klipsch R-51M the better fit for near-field listening and a small room, and Polk RTi A3 for a mid-size room and a large room.
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.