In this review, we will be comparing RP-500M II and R-51M, two Passive Bookshelf speakers by Klipsch.
Let's have a brief look at the main features
of Klipsch RP-500M II and Klipsch R-51M first before getting into our more
detailed comparison.
| Key Specs | Klipsch RP-500M II | Klipsch R-51M |
|---|
| Brand | Klipsch
United States · founded 1946 | Klipsch
United States · founded 1946 |
|---|
| Design | 2-way | 2-way |
|---|
| Tweeter | 1" Hybrid Tractrix Horn | 1" Tractrix Horn |
|---|
| Woofer | 5.25" Cerametallic cone | 5.25" Copper-spun IMG |
|---|
| Frequency response | 50-25k Hz | 62-21k Hz |
|---|
| Sensitivity | 92 dB | 93 dB |
|---|
| Impedance | 8 ohms | 8 ohms |
|---|
| Power range | up to 75 watts | Up to 85 watts |
|---|
| Weight | 6.00kg / 13.2lbs | 5.00kg / 11lbs |
|---|
| Dimensions (H x W x D) | 13-9/16" x 6-7/8" x 10-5/8"
345.0 x 175.0 x 270.0mm | 13.3" x 7.0" x 8.4"
338.0 x 178.0 x 215.0mm |
|---|
What size room are the Klipsch RP-500M II 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* |
Klipsch RP-500M II |
Klipsch R-51M |
| Near-field |
Good |
Average |
| Small Room |
Good |
Good |
| Mid-size Room |
Average |
Average |
| Large Room |
Poor |
Poor |
| Very Large Room |
No way |
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.
Drivers
Both RP-500M II and R-51M are 2-way speakers.
Klipsch RP-500M IIKlipsch R-51M
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 RP-500M II |
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
|
RP-500M II features a 1" titanium Hybrid Tractrix Horn Tweeter and 1 x 5.25" Cerametallic cone Woofer with a Crossover frequency at 1530 Hz. 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
RP-500M II has a frequency range of 50-25k Hz whereas R-51M has a frequency range of 62-21k Hz. With a minimum frequency of 50Hz, the RP-500M II 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
RP-500M II and R-51M have the same Impedance of 8 ohms but where they differ is the sensitivity levels. RP-500M II sensitivity is rated at 92 dB and the R-51M's is at 93 dB. This 1 dB difference makes the Klipsch R-51M a more sensitive speaker compared to Klipsch RP-500M II, 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.
R-51M can handle a max power of 85 watts RMS, whereas RP-500M II has a max power handling value of 75 watts RMS, 10 watts less than the R-51M.
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
RP-500M II features Single Gold Plated Binding Posts - 5-way type posts and R-51M has a Single Gold Plated Binding Posts - 5-way type posts. None of these speakers feature bi-amping/bi-wiring.
Klipsch RP-500M II's Binding post terminals
Klipsch R-51M's Single Gold Plated Binding Posts - 5-way terminals
Cabinet Type and Port Position
Both RP-500M II and R-51M 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
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 RP-500M II's and Klipsch R-51M's external dimensions. Klipsch RP-500M II has external dimensions of 345.0 x 175.0 x 270.0mm (13-9/16 x 6-7/8 x 10-5/8inch) 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 7mm shorter and 55mm less deeper than Klipsch RP-500M II but it is also 3mm wider.
Below you can see the front view size comparison of Klipsch RP-500M II and Klipsch R-51M in scale.
Comparison image of Klipsch RP-500M II 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 Klipsch RP-500M II is approximately 472.5cm2 / 73.2inch2 and base area of the Klipsch R-51M is approximately 382.7cm2 / 59.3inch2. The RP-500M II requires 23% more surface area than the R-51M which gives it a small disadvantage 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 RP-500M II 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 Klipsch RP-500M II weighs 6.00kg / 13.2lbs and the Klipsch R-51M weighs 5.00kg / 11lbs. This makes the RP-500M II 20% heavier than the R-51M.
Here is a comparison of how RP-500M II 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 Klipsch RP-500M II?
Here are the items that are included inside the box of RP-500M II:
- 2 Bookshelf loudspeakers
- 2 Grilles
- User Manual
- Important Safety Instructions
- Warranty Information
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
 Low Frequency Response |
50 Hz
vs
62 Hz
|
Generates deeper bass |
 High Frequency Response |
25k Hz
vs
21k Hz
|
Generates higher frequency |
 Max Input Power |
85 watts
vs
75 watts
|
Handle more power from your amplifier |
 Sensitivity |
93 dB
vs
92 dB
|
Play louder with same amount of amplification power |
 Height |
338mm
vs
345mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
382cm2
vs
472cm2
|
Takes less floor space |
 Price per pair* |
359USD
vs
599USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
Klipsch Reference Premiere RP-500M II |
Klipsch Reference R-51M |
| Brand |
Klipsch |
Klipsch |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
up to 75 watts |
Up to 85 watts |
| Sensitivity |
92 dB |
93 dB |
| Impedance |
8 ohms |
8 ohms |
| Frequency Response |
50-25k Hz |
62-21k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
5.25" |
5.25" |
| Woofer Composition |
Cerametallic cone |
Copper-spun IMG |
| Woofer Surround Material |
Rubber |
Rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
Hybrid Tractrix Horn |
Tractrix Horn |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
1530 Hz |
1660Hz |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
345.0mm (13.6") |
338.0mm (13.3") |
| Width |
175.0mm (6.9") |
178.0mm (7") |
| Depth |
270.0mm (10.6") |
215.0mm (8.5") |
| Weight |
6.00kg (13.2lbs) |
5.00kg (11lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
MDF/Wood-grain vinyl |
MDF/Wood-grain vinyl |
| Available Colors |
Walnut, Black |
Black |
| Mounting Bracket |
|
No |
| Recommended Stand Height |
24-28" |
24-28" |
| 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 |
These sit in different price classes - Klipsch RP-500M II costs roughly 1.7x what Klipsch R-51M does. Expect it to lead on paper; the question is whether the gap is audible enough in your room to be worth it.
| Area | Better | Why |
|---|
| Bass | A | Klipsch RP-500M II digs deeper - 50Hz against 62Hz. |
| Amplifier needs | evenly matched | Similar sensitivity (92dB vs 93dB) - both want much the same power. |
| Headroom | evenly matched | Similar power handling (75W vs 85W). |
| Size | depends | Klipsch R-51M is easier to place; Klipsch RP-500M II is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | depends | Neither adds bi-amping, a sub output or height drivers. Klipsch RP-500M II sits in a wider range (10 models), so a matched surround system is easier later. |
| Price | B | Klipsch R-51M is cheaper - $359 against $599, about 40% less; arguably a different class. |
A Klipsch RP-500M II B Klipsch R-51M
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?
Klipsch RP-500M II is ahead, but only on 1 of the measured areas, and it costs about 67% more. That is a lot of money for a narrow margin on paper - Klipsch R-51M looks like the sensible buy unless something else about the Klipsch RP-500M II appeals to you. 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 RP-500M II the better fit for near-field listening; elsewhere the two are rated the same.
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.