In this review, we will be comparing Passif 50 and R-51M, two Passive Bookshelf speakers from PSB and Klipsch. Let's have a brief look at the main features
of PSB Passif 50 and Klipsch R-51M first before getting into our more
detailed comparison.
What size room are the PSB Passif 50 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:
In the following sections, we will get into more detail in order to better understand how the PSB Passif 50 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 Passif 50 and R-51M are 2-way speakers.
| Driver |
PSB Passif 50 |
Klipsch R-51M |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 6.5-inch
|
1 x 5.25-inch
|
Passif 50 features a 1" titanium dome with ferrofluid and neodymium magnet Dome Tweeter and 1 x 6.5" cast aluminum basket, paper cone Woofer with a Crossover frequency at 1800Hz. 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
Passif 50 has a frequency range of 50-20k Hz whereas R-51M has a frequency range of 62-21k Hz. With a minimum frequency of 50Hz, the Passif 50 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.
Impedance and Sensitivity
Passif 50 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. Passif 50 sensitivity is rated at 87 dB and the R-51M's is rated at 93 dB. This 4 dB difference makes the Klipsch R-51M a more sensitive speaker compared to PSB Passif 50, 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.
Passif 50 can handle a max power of 200 watts RMS from the amp the whereas R-51M has a max power handling value of 85 watts RMS, 115 watts less than the Passif 50.
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
Passif 50 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.
PSB Passif 50's 5-Way post terminals allows Bi-amping or 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 PSB Passif 50's and Klipsch R-51M's external dimensions. PSB Passif 50 has external dimensions of 660 × 280 × 254mm ( 26 x 11 x 10-inch) 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 Passif 50 is clearly the larger of the two speakers. Its body is 102mm wider, 322mm taller and 39mm deeper than Klipsch R-51M.
Below you can see the front view size comparison of PSB Passif 50 and Klipsch R-51M in scale.
Comparison image of PSB Passif 50 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 Passif 50 is approximately 712.0cm2 / 110.4inch2 and base area of the Klipsch R-51M is approximately 382.7cm2 / 59.3inch2. The Passif 50 requires 86% more surface area than the R-51M which gives it a small disadvantage 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 PSB Passif 50 weighs 13.70kg / 30.1lbs and the Klipsch R-51M weighs 5.00kg / 11lbs. This makes the Passif 50 174% heavier than the R-51M.
Here is a comparison of how Passif 50 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 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 |
200 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 |
 Bi-Amping and Bi-Wiring |
Yes
vs
No
|
Allows bi-amping and bi-wiring connections |
 Passive Radiator |
one 8-inch
vs
None
|
Increases the bass performance |
 Sensitivity |
93 dB
vs
89 dB
|
Play louder with same amount of amplification power |
 Nominal Impedance |
8 ohms
vs
6 ohms
|
Less selective with amplifiers |
 High Frequency Response |
21k Hz
vs
20k Hz
|
Generates higher frequency |
 Height |
338mm
vs
660mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
382cm2 (178x215mm)
vs
712cm2 (280x254mm)
|
Takes less floor space |
 Price per pair* |
359USD
vs
2499USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
PSB Passif 50 |
Klipsch Reference R-51M |
| Brand |
PSB |
Klipsch |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
30-200 Watts watts |
Up to 85 watts |
| Sensitivity |
87 dB |
93 dB |
| Impedance |
6 ohms |
8 ohms |
| Impedance |
4 ohms |
n/a |
| Frequency Response |
50-20k Hz |
62-21k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
6.5" |
5.25" |
| Woofer Composition |
cast aluminum basket, paper cone |
Copper-spun IMG |
| Woofer Surround Material |
cast aluminum basket, paper cone |
Rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
Dome |
Tractrix Horn |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
1800Hz |
1660Hz |
| Firing Direction |
n/a |
rear |
Physical Specs |
|
|
| Height |
660.0mm (26") |
338.0mm (13.3") |
| Width |
280.0mm (11") |
178.0mm (7") |
| Depth |
254.0mm (10") |
215.0mm (8.5") |
| Weight |
13.70kg (30.1lbs) |
5.00kg (11lbs) |
| Enclosure |
Passive Radiator |
Bass Reflex |
| Finish |
open-grain walnut veneer |
MDF/Wood-grain vinyl |
| Available Colors |
Open-Grain Walnut |
Black |
| Mounting Bracket |
No |
No |
| Recommended Stand Height |
n/a |
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 |