In this review, we will be comparing C 91 II and R-51M, two Passive Bookshelf speakers from Jamo and Klipsch.
Let's have a brief look at the main features
of Jamo C 91 II and Klipsch R-51M first before getting into our more
detailed comparison.
| Key Specs | Jamo C 91 II | Klipsch R-51M |
|---|
| Brand | Jamo
Denmark · founded 1966 | Klipsch
United States · founded 1946 |
|---|
| Design | 2-way | 2-way |
|---|
| Tweeter | 1" Soft-Dome | 1" Tractrix Horn |
|---|
| Woofer | 4" Composite | 5.25" Copper-spun IMG |
|---|
| Frequency response | 65-24k Hz | 62-21k Hz |
|---|
| Sensitivity | 86 dB | 93 dB |
|---|
| Impedance | 6 ohms | 8 ohms |
|---|
| Power range | 50-100 watts | Up to 85 watts |
|---|
| Weight | 4.10kg / 9lbs | 5.00kg / 11lbs |
|---|
| Dimensions (H x W x D) | 10.4" x 6.7" x 7.5"
265.0 x 171.0 x 191.0mm | 13.3" x 7.0" x 8.4"
338.0 x 178.0 x 215.0mm |
|---|
What size room are the Jamo C 91 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* |
Jamo C 91 II |
Klipsch R-51M |
| 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.)
The sections below take each area in turn: drivers, frequency response, physical size and what you get in the box.
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through our links. As an Amazon Associate I earn from qualifying purchases.
Drivers
Both C 91 II and R-51M are 2-way speakers.
Jamo C 91 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 |
Jamo C 91 II |
Klipsch R-51M |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 4-inch
|
1 x 5.25-inch
|
C 91 II features a 1" Soft-Dome Tweeter and 1 x 4" Composite Woofer. 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
C 91 II has a frequency range of 65-24k Hz whereas R-51M has a frequency range of 62-21k Hz. With a minimum frequency of 62Hz, the R-51M can go slightly deeper then the C 91 II's min frequency of 65Hz.
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
C 91 II is a 6 ohms speaker compared to the R-51M which has a nominal impedance of 8 ohms.
These two speakers also have different sensitivity levels. C 91 II sensitivity is rated at 86 dB and the R-51M's is rated at 93 dB. This 7 dB difference makes the Klipsch R-51M a more sensitive speaker compared to Jamo C 91 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.
C 91 II can handle a max power of 100 watts RMS, whereas R-51M has a max power handling value of 85 watts RMS, 15 watts less than the C 91 II.
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
C 91 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.
Jamo C 91 II's 5-way post terminals
Klipsch R-51M's Single Gold Plated Binding Posts - 5-way terminals
Cabinet Type and Port Position
Both C 91 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 Jamo C 91 II's and Klipsch R-51M's external dimensions. Jamo C 91 II has external dimensions of 265.0 x 171.0 x 191.0mm (10.4 x 6.7 x 7.5inch) 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 clearly the larger of the two speakers. Its body is 7mm wider, 73mm taller and 24mm deeper than Jamo C 91 II.
Below you can see the front view size comparison of Jamo C 91 II and Klipsch R-51M in scale.
Comparison image of Jamo C 91 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 Jamo C 91 II is approximately 326.6cm2 / 50.6inch2 and base area of the Klipsch R-51M is approximately 382.7cm2 / 59.3inch2. The C 91 II requires 15% less surface area than the R-51M 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 Jamo C 91 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 Jamo C 91 II weighs 4.10kg / 9lbs and the Klipsch R-51M weighs 5.00kg / 11lbs. This makes the R-51M 22% heavier than the C 91 II.
Here is a comparison of how C 91 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 Jamo C 91 II?
Here are the items that are included inside the box of C 91 II:
- 2 Bookshelf loudspeakers
- 2 Grilles
- 8 Self-adhesive rubber feet
- 4 Self-adhesive rubber bumpers
- 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
 Max Input Power |
100 watts
vs
85 watts
|
Handle more power from your amplifier |
 High Frequency Response |
24k Hz
vs
21k Hz
|
Generates higher frequency |
 Mounting Bracket |
Yes
vs
No
|
Allows mounting on walls |
 Height |
265mm
vs
338mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
326cm2
vs
382cm2
|
Takes less floor space |
 Sensitivity |
93 dB
vs
86 dB
|
Play louder with same amount of amplification power |
 Nominal Impedance |
8 ohms
vs
6 ohms
|
Less selective with amplifiers |
 Woofer Size |
5.25 inches
vs
4 inches
|
Larger woofer |
|
Low Frequency Response |
62 Hz
vs
65 Hz
|
Generates deeper bass |
 Price per pair* |
359USD
vs
459USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
Jamo Concert 9 Series C 91 II |
Klipsch Reference R-51M |
| Brand |
Jamo |
Klipsch |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
50-100 watts |
Up to 85 watts |
| Sensitivity |
86 dB |
93 dB |
| Impedance |
6 ohms |
8 ohms |
| Frequency Response |
65-24k Hz |
62-21k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
4" |
5.25" |
| Woofer Composition |
Composite |
Copper-spun IMG |
| Woofer Surround Material |
Rubber |
Rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
Soft-Dome |
Tractrix Horn |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
n/a |
1660Hz |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
265.0mm (10.4") |
338.0mm (13.3") |
| Width |
171.0mm (6.7") |
178.0mm (7") |
| Depth |
191.0mm (7.5") |
215.0mm (8.5") |
| Weight |
4.10kg (9lbs) |
5.00kg (11lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
MDF/Wood-grain |
MDF/Wood-grain vinyl |
| Available Colors |
White Oak,Black Ash |
Black |
| Mounting Bracket |
Keyhole |
No |
| Recommended Stand Height |
28-32" |
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 |
No single best speaker here - they are built to different priorities, and the right one depends on your room, your amplifier and what you listen to.
| Area | Better | Why |
|---|
| Bass | B | Klipsch R-51M digs deeper - 62Hz against 65Hz. A subwoofer would even that out. |
| Amplifier needs | B | Klipsch R-51M is more sensitive (93dB vs 86dB), so it goes louder on the same amplifier. |
| Amplifier match | B | Klipsch R-51M is the easier load at 8 ohms. |
| Headroom | evenly matched | Similar power handling (100W vs 85W). |
| Size | depends | Jamo C 91 II is easier to place; Klipsch R-51M is bigger, which usually goes with fuller bass. Your room decides. |
| Price | B | Klipsch R-51M is cheaper - $359 against $459, about 22% less. |
A Jamo C 91 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 R-51M is the easier recommendation: it leads on most of the measured areas and costs less. Take Jamo C 91 II if its size, looks or fit in your room suit you better. In a large or open-plan room, Klipsch R-51M has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, Jamo C 91 II is the easier speaker to get right. If your amplifier is modest, vintage or valve-based, Klipsch R-51M is the safer partner - the other will want more current or more watts to sound its best.
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.