In this review, we will be comparing R-51M and 705 S2, two Passive Bookshelf speakers from Klipsch and Bowers Wilkins.
Let's have a brief look at the main features
of Klipsch R-51M and B&W 705 S2 first before getting into our more
detailed comparison.
| Key Specs | Klipsch R-51M | B&W 705 S2 |
|---|
| Brand | Klipsch
United States · founded 1946 | Bowers Wilkins
United Kingdom · founded 1966 |
|---|
| Design | 2-way | 2-way |
|---|
| Tweeter | 1" Tractrix Horn | 1" Solid Body Soft-Dome |
|---|
| Woofer | 5.25" Copper-spun IMG | 6.5" Continuum |
|---|
| Frequency response | 62-21k Hz | 50-28k Hz |
|---|
| Sensitivity | 93 dB | 88 dB |
|---|
| Impedance | 8 ohms | 8 ohms |
|---|
| Power range | Up to 85 watts | 30-120 watts |
|---|
| Weight | 5.00kg / 11lbs | 9.32kg / 20.5lbs |
|---|
| Dimensions (H x W x D) | 13.3" x 7.0" x 8.4"
338.0 x 178.0 x 215.0mm | 16" x 7.8" x 11.9"
407.0 x 200.0 x 301.0mm |
|---|
What size room are the Klipsch R-51M and B&W 705 S2 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 |
B&W 705 S2 |
| 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 705 S2 are 2-way speakers.
Klipsch R-51MB&W 705 S2
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 |
B&W 705 S2 |
|
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 705 S2 features a 1" Solid Body Soft-Dome Tweeter and 1 x 6.5" Continuum Woofer.
Frequency Response
R-51M has a frequency range of 62-21k Hz whereas 705 S2 has a frequency range of 50-28k Hz. With a minimum frequency of 50Hz, the 705 S2 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 705 S2 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 705 S2's is at 88 dB. This 5 dB difference makes the Klipsch R-51M a more sensitive speaker compared to B&W 705 S2, 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.
705 S2 can handle a max power of 120 watts RMS, whereas R-51M has a max power handling value of 85 watts RMS, 35 watts less than the 705 S2.
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
705 S2 features Binding post 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
Both R-51M and 705 S2 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 R-51M's and B&W 705 S2'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 B&W 705 S2 has external dimensions of 407.0 x 200.0 x 301.0mm (16-inch x 7.8-inch x 11.9-inch).
B&W 705 S2 is clearly the larger of the two speakers. Its body is 22mm wider, 69mm taller and 86mm deeper than Klipsch R-51M.
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 B&W 705 S2 is approximately 602.0cm2 / 93.3inch2. The R-51M requires 36% less surface area than the 705 S2 which gives it a small advantage 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 B&W 705 S2 weighs 9.32kg / 20.5lbs. This makes the 705 S2 86% heavier than the R-51M.
Here is a comparison of how R-51M and 705 S2'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 B&W 705 S2?
Here are the items that come with the 705 S2:
- 2 Bookshelf loudspeakers
- 2 Grilles
- 2 Two-piece foam port plugs
- 8 Self-adhesive rubber feet
- 4 Jumper-straps
- Manual
- Bowers & Wilkins brochure
- Warranty Information
 Sensitivity |
93 dB
vs
88 dB
|
Play louder with same amount of amplification power |
 Height |
338mm
vs
407mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
382cm2
vs
602cm2
|
Takes less floor space |
 Price per pair* |
359USD
vs
3299USD
|
costs less (*prices may change depending on the seller, location and time) |
 Max Input Power |
120 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 |
28k Hz
vs
21k Hz
|
Generates higher frequency |
 Bi-Amping and Bi-Wiring |
Yes
vs
No
|
Allows bi-amping and bi-wiring connections |
| General |
Klipsch Reference R-51M |
Bowers & Wilkins 705 S2 |
| Brand |
Klipsch |
Bowers Wilkins |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
Up to 85 watts |
30-120 watts |
| Sensitivity |
93 dB |
88 dB |
| Impedance |
8 ohms |
8 ohms |
| Impedance |
n/a |
3.1 ohms |
| Frequency Response |
62-21k Hz |
50-28k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
5.25" |
6.5" |
| Woofer Composition |
Copper-spun IMG |
Continuum |
| Woofer Surround Material |
Rubber |
Rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
Tractrix Horn |
Solid Body Soft-Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
1660Hz |
n/a |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
338.0mm (13.3") |
407.0mm (16") |
| Width |
178.0mm (7") |
200.0mm (7.9") |
| Depth |
215.0mm (8.5") |
301.0mm (11.9") |
| Weight |
5.00kg (11lbs) |
9.32kg (20.5lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
MDF/Wood-grain vinyl |
MDF/Wood veneer |
| Available Colors |
Black |
Rosewood, Gloss Black, Satin White |
| Mounting Bracket |
No |
No |
| Recommended Stand Height |
24-28" |
24-26" |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
No |
Yes |
Other |
|
|
| Parts Warranty |
5 Years |
5 Years |
| Labor Warranty |
5 Years |
5 Years |
These sit in different price classes - B&W 705 S2 costs roughly 9.2x 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 | B | B&W 705 S2 digs deeper - 50Hz against 62Hz. |
| Amplifier needs | A | Klipsch R-51M is more sensitive (93dB vs 88dB), so it goes louder on the same amplifier. |
| Headroom | B | B&W 705 S2 takes more power (120W vs 85W) - more in hand in a big room. |
| Size | depends | Klipsch R-51M is easier to place; B&W 705 S2 is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | B | B&W 705 S2: bi-amping. B&W 705 S2 sits in a wider range (8 models), so a matched surround system is easier later. |
| Price | A | Klipsch R-51M is cheaper - $359 against $3,299, about 89% less; arguably a different class. |
A Klipsch R-51M B B&W 705 S2
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: B&W 705 S2 measures better, Klipsch R-51M costs about about 9.2x the price% 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 B&W 705 S2 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.