In this review, we will be comparing Alpha AM5 and R-51M, two Bookshelf speakers from PSB and Klipsch. The main difference between these two speakers is that the PSB Alpha AM5 is a Powered speaker which means that it has a built-in amplifier inside the speaker body so you don't need an external power amp or an integrated amp whereas the Klipsch R-51M is a Passive speaker so has to be matched with an amplifier to get any sound from it. Let's have a brief look at the main features
of PSB Alpha AM5 and Klipsch R-51M first before getting into our more
detailed comparison.
PSB Alpha AM5 Key Specs
- 2-way Design
- 100-watt RMS Integrated Amplifier
- 0.75" Hard-Dome Tweeter
- 5.25" Polypropylene Woofer
- 55-20k Hz Frequency Response
- 24-bit Max Depth / 48 kHz Max Sample Rate
- Built-in 5.0 Bluetooth
- Weight:9.75kg
- Dimensions (H x W x D): 292.1" x 6.75" x 11"( 292.1 x 171.5 x 279.4mm )
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 )
In the following sections, we will get into more detail in order to better understand how the PSB Alpha AM5 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.
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Drivers
Both Alpha AM5 and R-51M are 2-way speakers.
| Driver |
PSB Alpha AM5 |
Klipsch R-51M |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
0.75-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5.25-inch
|
1 x 5.25-inch
|
Alpha AM5 features a 0.75" Aluminum 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
Alpha AM5 has a frequency range of 55-20k Hz whereas R-51M has a frequency range of 62-21k Hz. With a minimum frequency of 55Hz, the Alpha AM5 can go significantly deeper on the low side and provide stronger bass compared to the R-51M's min frequency of 62Hz.
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 Alpha AM5 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
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 PSB Alpha AM5's and Klipsch R-51M's external dimensions. PSB Alpha AM5 has external dimensions of 292.1 x 171.5 x 279.4mm ( 11.5 x 6.75 x 11inch) whereas Klipsch R-51M has external dimensions of 338.0 x 178.0 x 215.0mm ( 13.3 x 7.0 x 8.4inch) .
PSB Alpha AM5 is 6.5mm narrower and 45.9mm shorter than Klipsch R-51M but it is also 64.4mm deeper.
Below you can see the front view size comparison of PSB Alpha AM5 and Klipsch R-51M in scale.
Comparison image of PSB Alpha AM5 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 PSB Alpha AM5 is approximately 479.2cm2 / 74.3inch2 and base area of the Klipsch R-51M is approximately 382.7cm2 / 59.3inch2. The Alpha AM5 requires 25% 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 PSB Alpha AM5 and Klipsch R-51M on a Media Console
What's in the Box of PSB Alpha AM5?
Here are the items that are included inside the box of Alpha AM5:
Powered speaker Passive speaker 2 Grilles AC power adapter (attached 45-inch DC cord) 4-feet AC power cord Remote control (PSR-1) 2 AAA batteries 8-feet Speaker cable 58-inch Stereo minijack cable 8 Self-adhesive rubber feet Connection Diagram Warranty Card
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
Speaker Type 
Low Frequency Response 
Height 
3.5mm Connection 
High Frequency Response 
Base Surface Area 
Price per pair*