Review: Klipsch Reference R-51M bookshelf speakers


I have owned huge planar speakers with heavy tube amps as well as top of the line professional studio monitors. It is pretty safe to say I have an idea what a good speaker sounds like. We are living on an age where anyone with a keyboard, or worse - a video camera, can pretend to be an expert on the Internet, so I wanted to say this first.

2-way bookshelf speakers are not rocket science. You put a tweeter and a woofer in a cabinet size of a small birdhouse and design the crossover to match your speaker’s elements. You can manufacture and sell decent pair of speakers for around 200 dollars or euros. This has not changed during the last couple of decades. If it sounds bad, then your engineering is wrong. Plain and simple.

One way to ruin compact speakers is to push bass frequencies too low or over emphasizing them. There is a bit a specs race going on as the laws of physics limit the capabilities of small speakers – the manufacturers want to show an impressive number on the marketing data. If you want big sound, then you need big speakers (or a subwoofer). Period.

The American manufacturer Klipsch is one of the very few brands in the audio industry that think and execute things a little differently. They thrive on five key priciples:

  • High sensitivity (efficiency)
  • Low modular distortion
  • Wide dynamic range
  • Controlled directivity
  • Flat frequency response

The Klipsch Reference R-51M

In August 2018 Klipsch announced their whole new Reference series, a selection of entry level speakers of various sizes. The marketing talk is that while they look similar to the older models, their design and engineering is completely new. They are sold around 250-280 $/€ so they wont break your bank either.

The R-51M is the second smallest model of the line-up. It has a typical 5,25" woofer paired with a 1" aluminum tweeter that utilizes Klipsch signature horn design. It looks like something that came from the 1980’s or 90’s, with the exception of copper colored woofers. Looking at the specs sheet there are two numbers worth of your attention.

Sensitivity: 93db (@2.83V/1m)

The R-51M, like all Klipsch speakers, are highly sensitive. This makes them an easy load for the amplifier, and they play as loud as 93db with just 1 watt of power. Just about any Hi-Fi amplifier can drive them effortlessly, so no need to spend a lot of money on amplification power. Most likely your old amp will do just fine. On the other hand, if you want to go exotic they are a good match for lower powered tube amps as well.

Frequency response: 62 - 21 000 Hz (+/-3db)

The -3db point is at 62Hz, which is a fitting number for a speaker of this size. This gives you a tight and controlled bass, with plenty of detail. They have feed tapping kick in the sound, while you hear the nuances of bass strings and drum skins. They will not produce lowest rumbles in the movies though, so if you need those then you should get a subwoofer (or huge speakers).

The speaker cabinets have a bass reflex port on the rear side, so do leave a little bit of space behind them. If you are experiencing boomy bass, then move the speakers forward or you can block the bass reflex port - a piece of a sponge or a tennis sock rolled as a ball will do just fine.

How do they sound?

I tested the speakers at my own home, a small apartment with concrete walls and terrible acoustics. I have improved the listening conditions with natural elements like a bookshelf, leather sofa and a thick carpet on the floor. So this is a very realistic environment for people who are considering compact speakers - not a recording studio. I connected them to a Marantz NR-1403 AV-amplifier, which is a budget model, but has received positive reviews a few years ago. So nothing fancy on the amp either.

The Klipsch R-51M is nothing short of amazing, considering the price, and their signature Klipsch sound gives them an edge against the market competition. They are dynamic, lively, musical and deliver a punch that makes your feet tap and puts a smile on your face. They deliver a surprisingly wide soundscape, but perhaps not the most accurate one. In this sense they sound bigger then they are. To me it was a surprise that they work well for background music as they fill the room very nicely. You do not have to sit right in front of them to enjoy music.

Many reviews and opinion pieces say that the Klipsch speakers are overly bright or harsh, but I can’t say that I hear any of that. The highest frequencies may lack a little in terms of finest detail, but I did not find the sound irritating.

One very useful feature for me is that these speakers play very well on low volumes, too. With many speakers you need to push the volume up before the sound opens up, but that is not the case here. The R-51M is very enjoyable even with lowest volumes, a feature which you and your neighbors will appreciate during those late evening music or movie sessions.

Playing music

The Klipsch R-51M excels on guitar driven classic rock, like AC/DC. Electric guitars, drums and vocals are delivered with a punch. They are equally suitable for rap and electronic music, where you have the feet tapping bass kicking in, while still being able to reproduce the sugary voice of Pharrell Williams. Acoustic guitar really hits the notes as well and so does Mark Knopfler’'s buttery smooth guitar handling.

If you want to look for weaknesses, I find strings (violin, cello) to be slightly uninspiring with these boxes. They also have some challenges with modern rock like Ghost, which has so much of everything in the sound (guitars, vocals, keyboards…) that sometimes I felt that there simply is not enough resolution – this situation is likely the same with most 2-way speakers.

Note that room acoustics play a dominant role here, so it could be that the echoes in my concrete room is causing interferences on the areas were I found weaknesses.

Final thoughts

The new Klipsch Reference R-51M is an excellent compact speaker with a wallet friendly price tag. They deliver a delightful sound with tight bass and excellent rhythm. They work well as they are, but can be paired with a matching subwoofer for the lowest bass and they should also make a good component for a home theater as well (not tested here). They are definitely one of the better speakers you can buy in this price range and you need to shell out a serious pile of money in order to get significant improvements over these.

Highly recommended. :speaker: :musical_note: :blush:


Klipsch website for more details, photos and specs:

Wikipedia for some background info on Klipsch:

A second opinion by CNET:

Steve Guttenberg talks about horn speakers

If you go over to the Audio Science Review website they test the smaller brother of this speaker, the Klipsch R-41M. Unfortunately it comes out as not having a flat frequency response, a distorted sound, a difficult load for an amplifier and not as sensitive as advertised. It could be that all this adds up to produce the Klipsch signature sound that the reviewer describes. I prefer my speakers to sound like the music being played without adding their own signature.
Pity really as they do look pretty.