In this review, we will be comparing R-51PM and HD6, two Powered Bookshelf speakers from Klipsch and Audioengine. Being Powered speakers, they both have built-in amplifiers so you don't need an external power amp or an integrated amp to power them.
Let's have a brief look at the main features
of Klipsch R-51PM and Audioengine HD6 first before getting into our more
detailed comparison.
Klipsch R-51PM Key Specs
- 2-way Design
- 120-watt RMS( 240-watt Peak) Integrated Amplifier
- 1.0" Tractrix Horn Tweeter
- 5.25" Copper-spun IMG Woofer
- 68-21k Hz Frequency Response
- 24-bit Max Depth / 96 kHz Max Sample Rate
- Built-in 3.0 Bluetooth
- Weight:4.80kg
- Dimensions (H x W x D): 330.2" x 7.0625" x 10.25"( 330.2 x 179.4 x 260.3mm )
Audioengine HD6 Key Specs
- 2-way Design
- 100-watt RMS( 200-watt Peak) Integrated Amplifier
- 1" Soft-Dome Tweeter
- 5.5" Kevlar Woofer
- 50-22k Hz Frequency Response
- 24-bit Max Depth / 192 kHz Max Sample Rate
- Built-in 5.0 Bluetooth
- Weight:5.50kg
- Dimensions (H x W x D): 314.3" x 7.1875" x 12.5"( 314.3 x 182.6 x 317.5mm )
In the following sections, we will get into more detail in order to better understand how the Klipsch R-51PM and Audioengine HD6 compare and hopefully end up with enough arguments to decide which one of these loudspeakers is the better choice for you.
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Drivers
Both R-51PM and HD6 are 2-way speakers.
| Driver |
Klipsch R-51PM |
Audioengine HD6 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1.0-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5.25-inch
|
1 x 5.5-inch
|
R-51PM features a 1.0" Aluminum LTS Tractrix Horn Tweeter and 1 x 5.25" Copper-spun IMG Woofer with a Crossover frequency at 1663Hz. On the other hand, the HD6 features a 1" Silk Soft-Dome Tweeter and 1 x 5.5" Kevlar Woofer .
Frequency Response
R-51PM has a frequency range of 68-21k Hz whereas HD6 has a frequency range of 50-22k Hz. With a minimum frequency of 50Hz, the HD6 can go significantly deeper on the low side and provide stronger bass compared to the R-51PM's min frequency of 68Hz.
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.
Cabinet Type and Port Position
Both R-51PM and HD6 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
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 Klipsch R-51PM's and Audioengine HD6's external dimensions. Klipsch R-51PM has external dimensions of 330.2 x 179.4 x 260.3mm ( 13 x 7.0625 x 10.25inch) whereas Audioengine HD6 has external dimensions of 314.3 x 182.6 x 317.5mm ( 12.375 x 7.1875 x 12.5inch) .
Klipsch R-51PM is 3.2mm narrower and 57.2mm less deeper than Audioengine HD6 but it is also 15.9mm taller.
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-51PM is approximately 467.0cm2 / 72.4inch2 and base area of the Audioengine HD6 is approximately 579.8cm2 / 89.9inch2. The R-51PM requires 19% less surface area than the HD6 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-51PM weighs 4.80kg / 10.6lbs and the Audioengine HD6 weighs 5.50kg / 12.1lbs. This makes the HD6 15% heavier than the R-51PM.
Here is a comparison of how R-51PM and HD6's weights compare with the average, max and min weights in Powered Bookshelf class.
Weight
All Bookshelf Speakers
What's in the Box of Klipsch R-51PM?
Here are the items that are included inside the box of R-51PM:
Powered speaker (right)Passive speaker (left)2 Grilles68-inch AC power cordRemote control2
What's in the Box of Audioengine HD6?
Here are the items that come with the HD6:
Powered speaker Passive speaker 2 Grilles (pre-installed) 6-feet AC power cord Bluetooth antenna Remote control 13-feet Speaker cable (w/ banana connectors on each end) 6.5-feet Stereo minijack cable 2 Microfiber speaker bags MIcrofiber cable bag Quickstart Guide Product Line Brochure
 Base Surface Area |
467cm2
vs
579cm2
|
Takes less floor space |
 Price per pair* |
599USD
vs
699USD
|
costs less (*prices may change depending on the seller, location and time) |
 USB Port |
USB-B
vs
No
|
USB port adds flexibility |
 Phono Input |
Yes
vs
No
|
Connect your turntable directly |
 Woofer Size |
5.5 inches
vs
5.25 inches
|
Larger woofer |
|
Low Frequency Response |
50 Hz
vs
68 Hz
|
Generates deeper bass |
 High Frequency Response |
22k Hz
vs
21k Hz
|
Generates higher frequency |
 Height |
314mm
vs
330mm
|
Easier to fit in smaller spaces |
| General |
Klipsch Reference R-51PM |
Audioengine HD6 |
| Brand |
Klipsch |
Audioengine |
| Speaker Type |
Powered Stereo Speakers |
Powered Stereo Speakers |
| Frequency Response |
68-21k Hz |
50-22k Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
120-watt RMS |
100-watt RMS |
| Watts Peak (Max) |
240-watt RMS |
200-watt RMS |
| Max Bit Depth |
24-bit |
24-bit |
| Max Sample Rate |
96 kHz |
192 kHz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
5.25" |
5.5" |
| Woofer Composition |
Copper-spun IMG |
Kevlar |
| Tweeter Size |
1.0" |
1" |
| Tweeter Type |
Tractrix Horn |
Soft-Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
1663Hz |
n/a |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
330.2mm (13") |
314.3mm (12.4") |
| Width |
179.4mm (7.1") |
182.6mm (7.2") |
| Depth |
260.3mm (10.2") |
317.5mm (12.5") |
| Weight |
4.80kg (10.6lbs) |
5.50kg (12.1lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Available Colors |
n/a |
Black, Walnut, White, Cherry Wood |
| Mounting Bracket |
No |
No |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Aux Inputs |
3.5mm, RCA |
3.5mm, RCA |
| USB Port |
USB-B |
No |
| Phone Input |
Yes |
No |
| Subwoofer Output |
Wired |
Wired |
| Digital Input |
Optical |
Optical |
| HDMI Input |
No |
No |
| Headphone Jack |
No |
No |
| Ethernet Port |
No |
No |
Other |
|
|
| Parts Warranty |
1 Year |
3 Years |
| Labor Warranty |
1 Year |
3 Years |