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Klipsch Reference R-51M Review

Main Features

  • 1" Tractrix Horn Tweeter
  • 5.25" Copper-spun IMG Woofer
  • 62-21k Hz Frequency Response
  • 93 dB Sensitivity
  • Impedance: 8ohms
  • Power Range:85watts
  • Weight:11 lbs
  • Dimensions (H x W x D): 13.3" x 7.0" x 8.4"
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Klipsch R-51M Review

R-51M is a 2-way Passive Bass Reflex Bookshelf speaker by Klipsch. It features a 1" Tractrix Horn Tweeter and 1 x 5.25" Copper-spun IMG Woofer. The speaker has a frequency range of 62-21k Hz and a sensitivity of 93 dB. Klipsch R-51M has an MSRP of 359$ per pair but can often be found around 249$ per pair.

R-51M is a member of Klipsch's Reference (R) series of Passive speakers. Below you can see the main specs of these speakers.

Klipsch Reference (R) Series Speakers
Model Frequency SensitivityImpedance Woofer
Klipsch R-51M
62-21k Hz 93 dB8Ω 1 x 5.25"
Klipsch R-625FA
Compare
38-21k Hz 96 dB8Ω 2 x 6.5"
Klipsch R-620F
Compare
38-21k Hz 96 dB8Ω 2 x 6.5"
Klipsch R-41M
Compare
68-21k Hz 90 dB8Ω 1 x 4"
Klipsch R-820F
Compare
35-21k Hz 97 dB8Ω 2 x 8"
Klipsch R-610F
Compare
45-21k Hz 94 dB8Ω 1 x 6.5"
Klipsch RF-7 III
Compare
32-25k Hz 100 dB8Ω 2 x 10"
Klipsch R-34C
Compare
82-21k Hz 96 dB8Ω 4 x 3.5"
Klipsch R-52C
Compare
89-21k Hz 95 dB8Ω 2 x 5.25"


**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.

Frequency Response

Klipsch R-51M has a Frequency response range of 62-21k Hz at ±3dB and Power Range of 85 watts. At a minimum frequency of 62 Hz, it is hard to expect a strong bass response from R-51M so depending on your intended use, using a subwoofer will significantly help to widen the response range. Here we have a comparison of how R-51M's Low and High frequency values compare with the average, max and min Low and High frequency values in its class.

Low Frequency
Bookshelf Speakers
Klipsch R-51M
Min
Average
Max
High Frequency
Bookshelf Speakers
Klipsch R-51M
Min
Average
Max

Among the speakers in our database with a max MSRP price of 500$ (Pair), these are the 5 Passive Bookshelf speakers that have the deeper bass levels than the Klipsch R-51M's 62Hz:

  • Polk XT20 with Low Frequency of 38 Hz (Compare w/ R-51M)
  • Cambridge SX-60 with Low Frequency of 41 Hz (Compare w/ R-51M)
  • Polk ES20 with Low Frequency of 41 Hz (Compare w/ R-51M)
  • ELAC Debut 2.0 B6.2 with Low Frequency of 44 Hz (Compare w/ R-51M)
  • Polk ES15 with Low Frequency of 44 Hz (Compare w/ R-51M)


What is the Crossover frequency of Klipsch R-51M?

Crossover frequency of the R-51M is set to 1660Hz. This is the threshold frequency where the higher frequency signals over this level are sent to the tweeter and the lower frequency signals are sent to the woofer by the crossover component.

Impedance and Sensitivity

Klipsch R-51M's nominal impedance level is 8 ohms and has a sensitivity of 93 dB.

Sensitivity
Bookshelf Speakers
Klipsch R-51M
Min
Average
Max

Is the Klipsch Reference R-51M an easy to drive speaker?

8 Ohms is pretty much the standard impedance amongst stereo speakers and amplifiers so Klipsch Reference R-51M is not considered a difficult to drive speaker from nominal Impedance perspective.

93dB of Klipsch Reference R-51M is considered a high sensitivity compared to average stereo speaker which makes R-51M an easy to drive from Sensitivity perspective.

Input Type

R-51M features Single Gold Plated Binding Posts - 5-way type connectors. Bi-amping and Bi-wiring is not possible.
Klipsch R-51M Back View
Klipsch R-51M Back View

Klipsch R-51M Speaker Size: Weight and Dimensions

Klipsch R-51M has external dimensions of (Height x Width x Depth) 13.3 x 7.0 x 8.4inch (338.0 x 178.0 x 215.0mm ). Each speaker weighs 5.00kg / 11lbs.

To have a better perspective on the real life size of Klipsch R-51M, let's compare it with a standard size Compact Disc which has a diameter of 4.7inch (120mm).

Klipsch R-51M Real Life Body Size Comparison
Klipsch R-51M Speaker Size Compared to a Compact Disc

Here we place the Klipsch R-51M virtually next to a standard width amplifier and turntable on a BDI Octave Media Cabinet to get a better idea about the size.

Klipsch R-51M placed next to an amplifier and turntable
Klipsch R-51M Speaker next to an amplifier and turntable

Cabinet type and Materials

Klipsch R-51M has a Bass Reflex type cabinet and MDF/Wood-grain vinyl finish. Bass Reflex type loudspeakers (aka Ported, Vented or Reflex Port) have enclosures that uses a port, hole or vent cut into the cabinet. Ported designs are generally more efficient than the Sealed designs.

Speaker Feet

Klipsch R-51M comes with 8 Self-adhesive rubber feet which you can use to secure your loudspeaker on the surface that you are putting on.

It is always recommended to use some kind of feet under all types of speakers. Besides limiting the movement of the speakers, it also compensates for non-flat surfaces and limits the contact surface area of the speaker. Rubber based feet also help isolating the vibrations within certain frequency ranges.

Port Position

Klipsch R-51M is a rear-firing port speaker so you have to make sure you leave enough space between the back of the speaker and wall or bookshelf so that it has room to breathe.

Available colors

Klipsch R-51M is available in Black.

Wall Mounting

R-51M doesn't sport any built-in mounting bracket so you need an external structure to mount on walls.

What's in the Box of Klipsch R-51M?

Here are the items that are included inside the box of R-51M:
  • 2 Bookshelf loudspeakers
  • 2 Grilles (installed)
  • 8 Self-adhesive rubber feet
  • Quick Setup Guide
  • Important Safety Instructions
  • Warranty Information
  • User's Manual

    For more information about how to setup, use and maintain the Klipsch Reference R-51M, use the direct link below to download the official manual document:
    Download User Manual for Klipsch R-51M

    Official Brochure

    Here is a link to download the official brochure for the Klipsch Reference R-51M speaker:
    Official Brochure for Klipsch R-51M

    Official Product Page

    Official manufacturer's product page for the Klipsch Reference R-51M speaker can be found below:
    Official Product Page for Klipsch R-51M

    Warranty

    5 Years of parts warranty and 5 Years of labor warranty is generally provided by the manufacturer.


    Klipsch Reference R-51M Alternatives in Passive Bookshelf Speakers
    Model Type Sensitivity Impedance Frequency
    B&W 606 S2
    Compare
    2-way 88 dB 8 ohms 52-28k Hz
    B&W 606
    Compare
    2-way 88 dB 8 ohms 52-28k Hz
    Wharfedale Elysian 2
    Compare
    3-way 89 dB 4 ohms 35-22k Hz
    Klipsch RP-400M
    Compare
    2-way 93 dB 8 ohms 52-25k Hz
    ELAC Debut 2.0 B6.2
    Compare
    2-way 87 dB 6 ohms 44-35k Hz
    Wharfedale EVO4.1
    Compare
    2-way 87 dB 8 ohms 64-22k Hz
    Klipsch RP-500M
    Compare
    2-way 93 dB 8 ohms 48-25k Hz
    Klipsch RP-600M
    Compare
    2-way 96 dB 8 ohms 45-25k Hz
    Polk TSi100
    Compare
    2-way 89 dB 8 ohms 61-24k Hz
    Jamo S 801
    Compare
    2-way 85 dB 8 ohms 76-26k Hz
    Monitor Audio Bronze 1
    Compare
    2-way 88 dB 8 ohms 55-30k Hz
    Wharfedale LINTON
    Compare
    3-way 90 dB 6 ohms 40-20k Hz
    KEF Q150
    Compare
    2-way 86 dB 8 ohms 51-28k Hz
    Klipsch R-41M
    Compare
    2-way 90 dB 8 ohms 68-21k Hz
    Wharfedale EVO4.2
    Compare
    3-way 88 dB 8 ohms 54-22k Hz
    B&W 706 S2
    Compare
    2-way 88 dB 8 ohms 50-28k Hz
    Frequently Asked Questions about Klipsch Reference R-51M
    What is the External Dimensions of Klipsch Reference R-51M
    What is the Speaker Sensitivity of Klipsch Reference R-51M
    is the Klipsch Reference R-51M an easy to drive speaker?


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