KEF LS50 vs Cambridge SX-50 Comparison

Speaker to replace

Change

KEF LS50

Passive Bookshelf | 79-28k Hz

Check price atAmazon›

Change

Cambridge SX-50

Passive Bookshelf | 50-22k Hz

Check price atAmazon›

KEF LS50

Check price atAmazon›

Cambridge SX-50

Check price atAmazon›

KEF LS50

See at AMAZON

Cambridge SX-50

See at AMAZON

KEF LS50 vs Cambridge SX-50 Speaker Comparison

In this review, we will be comparing LS50 and SX-50, two Passive Bookshelf speakers from KEF and Cambridge Audio.

Let's have a brief look at the main features of KEF LS50 and Cambridge SX-50 first before getting into our more detailed comparison.

Key Specs	KEF LS50	Cambridge SX-50
Brand	KEF United Kingdom · founded 1961	Cambridge Audio United Kingdom · founded 1968
Design	2-way	2-way
Uni-Q driver	11th Generation Uni-Q	—
Tweeter	1" Vented dome	1" Dome
Woofer	5.25" Magnesium/aluminum alloy	5.25" Treated paper
Frequency response	79-28k Hz	50-22k Hz
Sensitivity	85 dB	90 dB
Impedance	8 ohms	8 ohms
Power range	25-100 watts	10-100 watts
Weight	7.20kg / 15.8lbs	3.00kg / 6.6lbs
Dimensions (H x W x D)	11.8" x 7.8" x 10.9" 302.0 x 200.0 x 278.0mm	8.8" x 6.3" x 9.4" 225.0 x 161.0 x 240.0mm

What size room are the KEF LS50 and Cambridge SX-50 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:

Listening Environment*	KEF LS50	Cambridge SX-50
Near-field	Average	Average
Small Room	Good	Good
Mid-size Room	Average	Average
Large Room	Poor	Poor
Very Large Room	Bad	Bad

(* Approximate Room sizes: Small < 100sq. ft / 9 m², Mid-size: 100-220 sq. ft / 9-20 m², Large 220-400 sq. ft / 20-36 m², Very Large: > 400 sq. ft / 36 m². Average Floor Height: 9" / 2.7m. Typical room sizes differ from country to country, and the actual listening experience changes depending on floor height, room shape, surface materials, listening position, speaker locations, etc.)

The sections below take each area in turn: drivers, frequency response, physical size and what you get in the box.

Drivers

Both LS50 and SX-50 are 2-way speakers.

KEF LS50

Cambridge SX-50

TweeterWoofer

Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.

Driver	KEF LS50	Cambridge SX-50
Driver Setup	2-way	2-way
Tweeter	1-inch	1-inch
Midrange	-	-
Woofer	1 x 5.25-inch	1 x 5.25-inch

LS50 features a 1" Aluminum Vented dome Tweeter and 1 x 5.25" Magnesium/aluminum alloy Woofer with a Crossover frequency at 2200Hz. On the other hand, the SX-50 features a 1" Silk Dome Tweeter and 1 x 5.25" Treated paper Woofer.

Frequency Response

LS50 has a frequency range of 79-28k Hz whereas SX-50 has a frequency range of 50-22k Hz. With a minimum frequency of 50Hz, the SX-50 can go significantly deeper on the low side and provide stronger bass compared to the LS50's min frequency of 79Hz.

The graph below depicts how these two speakers compare with the max, min and average Low Frequency values of other speakers in the Bookshelf class in our database.

Low Frequency

Bookshelf Speakers

LS50

SX-50

Min

Average

Median

Neither pair reaches down to 20Hz, the usual definition of full-range, which is normal for speakers of this size. If you want the bottom octave for movies or bass-heavy music, add a subwoofer to whichever you choose. Visit our Powered Subwoofers section to find out more about the available options.

Impedance and Sensitivity

LS50 and SX-50 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. LS50 sensitivity is rated at 85 dB and the SX-50's is at 90 dB. This 5 dB difference makes the Cambridge SX-50 a more sensitive speaker compared to KEF LS50, hence will play louder with the same amount of watts.

Sensitivity

Bookshelf Speakers

LS50

SX-50

Min

Average

Median

Power Range

Power range is the range of input power in watts RMS that a loudspeaker is designed to handle. Staying within that range gives nominal performance; driving the speaker beyond its maximum wattage can damage it.

Both handle the same maximum of 100 watts RMS, though LS50 is rated 25-100 watts and SX-50 10-100 watts.

Note that higher power handling does not make a speaker louder: that depends mainly on sensitivity and impedance. The calculator below shows how loud each of these actually plays on a real amplifier.

Which plays louder on your amplifier?

Starting with a popular amplifier - change it to the one you own, or any you are considering, and watch both numbers move.

Amplifier - change this

Distance

Playing as

KEF LS50

Cambridge SX-50

Input Type and Bi-Amping / Bi-Wiring

LS50 features 5-way post type posts and SX-50 has a 5-way post type posts. None of these speakers feature bi-amping/bi-wiring.

KEF LS50's Post terminals

Cambridge SX-50's 5-way post terminals

Cabinet Type and Port Position

Both LS50 and SX-50 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.

Cambridge SX-50 Port

Physical Specs

The size of a speaker can sometimes be an important decision factor due to space constraints or in some cases purely for esthetic reasons. In this section, we are going to compare KEF LS50's and Cambridge SX-50's external dimensions. KEF LS50 has external dimensions of 302.0 x 200.0 x 278.0mm (11.8 x 7.8 x 10.9inch) whereas Cambridge SX-50 has external dimensions of 225.0 x 161.0 x 240.0mm (8.8 x 6.3 x 9.4inch).

KEF LS50 is clearly the larger of the two speakers. Its body is 39mm wider, 77mm taller and 38mm deeper than Cambridge SX-50.

Below you can see the front view size comparison of KEF LS50 and Cambridge SX-50 in scale.

Comparison image of KEF LS50 and Cambridge SX-50 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 KEF LS50 is approximately 556.0cm² / 86.2inch² and base area of the Cambridge SX-50 is approximately 386.4cm² / 59.9inch². The LS50 requires 44% more surface area than the SX-50 which gives it a small disadvantage on placement in tight spaces.

Here is 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 KEF LS50 and Cambridge SX-50 on a Media Console

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 KEF LS50 weighs 7.20kg / 15.8lbs and the Cambridge SX-50 weighs 3.00kg / 6.6lbs. This makes the LS50 140% heavier than the SX-50.

Here is a comparison of how LS50 and SX-50's weights compare with the average, max and min weights in Passive Bookshelf class.

Weight
All Bookshelf Speakers

KEF LS50

Cambridge SX-50

Min

Average

Max

What's in the Box of KEF LS50?

Here are the items that are included inside the box of LS50:

2 Bookshelf loudspeakers
2 Foam port plugs
8 Self-adhesive rubber feet
Owner's Manual
Warranty Registration Card

What's in the Box of Cambridge SX-50?

Here are the items that come with the SX-50:

2 Bookshelf loudspeakers
2 Grilles
8 Self-adhesive feet
2 Foam port inserts
Installation Guide

Reasons to choose KEF LS50 over Cambridge Audio SX-50

High Frequency Response	28k Hz vs 22k Hz	Generates higher frequency

Reasons to choose Cambridge Audio SX-50 over KEF LS50

Sensitivity	90 dB vs 85 dB	Play louder with same amount of amplification power
Low Frequency Response	50 Hz vs 79 Hz	Generates deeper bass
Height	225mm vs 302mm	Easier to fit in smaller spaces
Base Surface Area	386cm² vs 556cm²	Takes less floor space
Price per pair*	199USD vs 1300USD	costs less (*prices may change depending on the seller, location and time)

KEF LS50 vs Cambridge SX-50 Specs Table

Detailed comparison of specifications

General	KEF LS50	Cambridge Audio SX-50
Brand	KEF	Cambridge Audio
Speaker Type	Bookshelf speakers	Bookshelf speakers
Power Range	25-100 watts	10-100 watts
Sensitivity	85 dB	90 dB
Impedance	8 ohms	8 ohms
Impedance	3.2 ohms	n/a
Frequency Response	79-28k Hz	50-22k Hz
Drivers
Woofer Quantity	1	1
Woofer Size	5.25"	5.25"
Woofer Composition	Magnesium/aluminum alloy	Treated paper
Woofer Surround Material	Rubber	Rubber
Tweeter Size	1"	1"
Tweeter Type	Vented dome	Dome
Aimable Tweeter	No	No
Midrange Driver	No	No
Crossover Frequency	2200Hz	n/a
Firing Direction	rear	rear
Physical Specs
Height	302.0mm (11.9")	225.0mm (8.9")
Width	200.0mm (7.9")	161.0mm (6.3")
Depth	278.0mm (10.9")	240.0mm (9.4")
Weight	7.20kg (15.8lbs)	3.00kg (6.6lbs)
Enclosure	Bass Reflex	Bass Reflex
Finish	Polymer/Lacquer	MDF/Woodgrain vinyl
Available Colors	Black, High Gloss Piano Black, High Gloss Piano White	Black
Mounting Bracket	No	No
Recommended Stand Height	18-28"	28-31"
Grille	n/a	Yes
Moisture Resistancy	No	No
Connections
Biamp Inputs	No	No
Other
Parts Warranty	5 Years	5 Years
Labor Warranty	5 Years	5 Years

Verdict

These sit in different price classes - KEF LS50 costs roughly 6.5x what Cambridge SX-50 does. Expect it to lead on paper; the question is whether the gap is audible enough in your room to be worth it.

Area	Better	Why
Bass	B	Cambridge SX-50 digs deeper - 50Hz against 79Hz.
Amplifier needs	B	Cambridge SX-50 is more sensitive (90dB vs 85dB), so it goes louder on the same amplifier.
Headroom	evenly matched	Similar power handling (100W vs 100W).
Size	depends	Cambridge SX-50 is easier to place; KEF LS50 is bigger, which usually goes with fuller bass. Your room decides.
Expandability	depends	Neither adds bi-amping, a sub output or height drivers. KEF LS50 sits in a wider range (10 models), so a matched surround system is easier later.
Price	B	Cambridge SX-50 is cheaper - $199 against $1,300, about 85% less; arguably a different class.

A KEF LS50 B Cambridge SX-50
depends neither is better in the abstract - it turns on your room, your system or how you will use them. Only specs published for both speakers are judged; anything missing on either side is left out rather than guessed.

Which should you choose?

Cambridge SX-50 is the easier recommendation: it leads on most of the measured areas and costs less. Take KEF LS50 if its size, looks or fit in your room suit you better. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 79Hz anyway, so judge these on the other rows instead. In a large or open-plan room, KEF LS50 has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, Cambridge SX-50 is the easier speaker to get right.

And remember what a spec sheet cannot show: how each looks in your room and whether the finish suits it, what dealer support and warranty are like where you live, and how they actually sound to you. If you can hear them first - ideally with your own music - that will tell you more than any number above.