In this review, we will be comparing Demand D9 and R-51M, two Passive Bookshelf speakers from Definitive Technology and Klipsch.
Let's have a brief look at the main features
of Definitive Demand D9 and Klipsch R-51M first before getting into our more
detailed comparison.
Definitive Demand D9 Key Specs
- 2-way Design
- 1" Hard-Dome Tweeter
- 5.25" Polypropylene Woofer
- 64-22k Hz Frequency Response
- 88 dB Sensitivity
- Impedance: 8ohms
- Power Range:20-150watts
- Weight:7.73kg
- Dimensions (H x W x D): 301.0" x 6-9/16" x 12-7/16"( 301.0 x 167.0 x 316.0mm )
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 Definitive Demand D9 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* |
Definitive Demand D9 |
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 Definitive Demand D9 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.
**This post contains affiliate links, and I will be compensated if you make a purchase after clicking
through my links. As an Amazon Associate I earn from qualifying purchases.
Drivers
Both Demand D9 and R-51M are 2-way speakers.
| Driver |
Definitive Demand D9 |
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
|
Demand D9 features a 1" Hard-Dome Tweeter and 1 x 5.25" Polypropylene 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
Demand D9 has a frequency range of 64-22k 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 Demand D9's min frequency of 64Hz.
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
Demand D9 and R-51M have the same Impedance of 8 ohms but where they differ is the sensitivity levels. Demand D9 sensitivity is rated at 88 dB and the R-51M's is at 93 dB. This 5 dB difference makes the Klipsch R-51M a more sensitive speaker compared to Definitive Demand D9, 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.
Demand D9 can handle a max power of 150 watts RMS from the amp the whereas R-51M has a max power handling value of 85 watts RMS, 65 watts less than the Demand D9.
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
Demand D9 features 5-Way 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
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 Definitive Demand D9's and Klipsch R-51M's external dimensions. Definitive Demand D9 has external dimensions of 301.0 x 167.0 x 316.0mm ( 11-13/16 x 6-9/16 x 12-7/16inch) whereas Klipsch R-51M has external dimensions of 338.0 x 178.0 x 215.0mm ( 13.3 x 7.0 x 8.4inch) .
Definitive Demand D9 is 11mm narrower and 37mm shorter than Klipsch R-51M but it is also 101mm deeper.
Below you can see the front view size comparison of Definitive Demand D9 and Klipsch R-51M in scale.
Comparison image of Definitive Demand D9 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 Definitive Demand D9 is approximately 527.7cm2 / 81.8inch2 and base area of the Klipsch R-51M is approximately 382.7cm2 / 59.3inch2. The Demand D9 requires 38% 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 Definitive Demand D9 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 Definitive Demand D9 weighs 7.73kg / 17lbs and the Klipsch R-51M weighs 5.00kg / 11lbs. This makes the Demand D9 55% heavier than the R-51M.
Here is a comparison of how Demand D9 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 Definitive Demand D9?
Here are the items that are included inside the box of Demand D9:
Left bookshelf loudpseakerRight bookshelf loudspeaker2 Grilles4 Jumper-straps (pre-installed)Cleaning clothOwners Manual
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 |
150 watts
vs
85 watts
|
Handle more power from your amplifier |
 High Frequency Response |
22k Hz
vs
21k Hz
|
Generates higher frequency |
 Bi-Amping and Bi-Wiring |
Yes
vs
No
|
Allows bi-amping and bi-wiring connections |
 Height |
301mm
vs
338mm
|
Easier to fit in smaller spaces |
 Sensitivity |
93 dB
vs
88 dB
|
Play louder with same amount of amplification power |
 Low Frequency Response |
62 Hz
vs
64 Hz
|
Generates deeper bass |
 Base Surface Area |
382cm2
vs
527cm2
|
Takes less floor space |
 Price per pair* |
359USD
vs
749USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
Definitive Technology Demand Series D9 |
Klipsch Reference R-51M |
| Brand |
Definitive Technology |
Klipsch |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
20-150 watts |
Up to 85 watts |
| Sensitivity |
88 dB |
93 dB |
| Impedance |
8 ohms |
8 ohms |
| Frequency Response |
64-22k Hz |
62-21k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
5.25" |
5.25" |
| Woofer Composition |
Polypropylene |
Copper-spun IMG |
| Woofer Surround Material |
Rubber |
Rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
Hard-Dome |
Tractrix Horn |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
n/a |
1660Hz |
| Firing Direction |
n/a |
rear |
Physical Specs |
|
|
| Height |
301.0mm (11.9") |
338.0mm (13.3") |
| Width |
167.0mm (6.6") |
178.0mm (7") |
| Depth |
316.0mm (12.4") |
215.0mm (8.5") |
| Weight |
7.73kg (17lbs) |
5.00kg (11lbs) |
| Enclosure |
Passive Radiator |
Bass Reflex |
| Finish |
MDF/Aluminum |
MDF/Wood-grain vinyl |
| Available Colors |
Gloss White,Piano Black |
Black |
| Mounting Bracket |
No |
No |
| Recommended Stand Height |
24-28" |
24-28" |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
Yes |
No |
Other |
|
|
| Parts Warranty |
5 Years |
5 Years |
| Labor Warranty |
5 Years |
5 Years |