Cambridge SX-50 vs KEF Q150 Comparison

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Cambridge SX-50

Passive Bookshelf | 50-22k Hz

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KEF Q150

Passive Bookshelf | 51-28k Hz

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Cambridge SX-50

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KEF Q150

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Cambridge SX-50

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KEF Q150

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Cambridge SX-50 vs KEF Q150 Speaker Comparison

In this review, we will be comparing SX-50 and Q150, two Passive Bookshelf speakers from Cambridge Audio and KEF.

Let's have a brief look at the main features of Cambridge SX-50 and KEF Q150 first before getting into our more detailed comparison.

Key Specs	Cambridge SX-50	KEF Q150
Brand	Cambridge Audio United Kingdom · founded 1968	KEF United Kingdom · founded 1961
Design	2-way	2-way
Uni-Q driver	—	11th Generation Uni-Q
Tweeter	1" Dome	1" Dome
Woofer	5.25" Treated paper	5.25" Aluminum
Frequency response	50-22k Hz	51-28k Hz
Sensitivity	90 dB	86 dB
Impedance	8 ohms	8 ohms
Power range	10-100 watts	10-100 watts
Weight	3.00kg / 6.6lbs	5.60kg / 12.3lbs
Dimensions (H x W x D)	8.8" x 6.3" x 9.4" 225.0 x 161.0 x 240.0mm	11.9" x 7.0" x 10.9" 303.0 x 180.0 x 278.0mm

What size room are the Cambridge SX-50 and KEF Q150 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*	Cambridge SX-50	KEF Q150
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 SX-50 and Q150 are 2-way speakers.

Cambridge SX-50

KEF Q150

TweeterWoofer

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

Driver	Cambridge SX-50	KEF Q150
Driver Setup	2-way	2-way
Tweeter	1-inch	1-inch
Midrange	-	-
Woofer	1 x 5.25-inch	1 x 5.25-inch

SX-50 features a 1" Silk Dome Tweeter and 1 x 5.25" Treated paper Woofer. On the other hand, the Q150 features a 1" vented aluminum Dome Tweeter and 1 x 5.25" Aluminum Woofer with a Crossover frequency at 2500Hz.

Frequency Response

SX-50 has a frequency range of 50-22k Hz whereas Q150 has a frequency range of 51-28k Hz. With a minimum frequency of 50Hz, the SX-50 can go slightly deeper then the Q150's min frequency of 51Hz.

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

SX-50

Q150

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

SX-50 and Q150 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. SX-50 sensitivity is rated at 90 dB and the Q150's is at 86 dB. This 4 dB difference makes the Cambridge SX-50 a more sensitive speaker compared to KEF Q150, hence will play louder with the same amount of watts.

Sensitivity

Bookshelf Speakers

SX-50

Q150

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.

SX-50 and Q150 have the same power range of 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

Cambridge SX-50

KEF Q150

Input Type and Bi-Amping / Bi-Wiring

SX-50 features Post type posts and Q150 has a Post type posts. None of these speakers feature bi-amping/bi-wiring.

Cambridge SX-50's 5-way post terminals

KEF Q150's Post terminals

Cabinet Type and Port Position

Both SX-50 and Q150 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

KEF Q150 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 Cambridge SX-50's and KEF Q150's external dimensions. Cambridge SX-50 has external dimensions of 225.0 x 161.0 x 240.0mm (8.8 x 6.3 x 9.4inch) whereas KEF Q150 has external dimensions of 303.0 x 180.0 x 278.0mm (11.9 x 7.0 x 10.9inch).

KEF Q150 is clearly the larger of the two speakers. Its body is 19mm wider, 78mm taller and 38mm deeper than Cambridge SX-50.

Below you can see the front view size comparison of Cambridge SX-50 and KEF Q150 in scale.

Comparison image of Cambridge SX-50 and KEF Q150 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 Cambridge SX-50 is approximately 386.4cm² / 59.9inch² and base area of the KEF Q150 is approximately 500.4cm² / 77.6inch². The SX-50 requires 23% less surface area than the Q150 which gives it a small advantage 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 Cambridge SX-50 and KEF Q150 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 Cambridge SX-50 weighs 3.00kg / 6.6lbs and the KEF Q150 weighs 5.60kg / 12.3lbs. This makes the Q150 87% heavier than the SX-50.

Here is a comparison of how SX-50 and Q150's weights compare with the average, max and min weights in Passive Bookshelf class.

Weight
All Bookshelf Speakers

Cambridge SX-50

KEF Q150

Min

Average

Max

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

Here are the items that are included inside the box of SX-50:

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

What's in the Box of KEF Q150?

Here are the items that come with the Q150:

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

Reasons to choose Cambridge Audio SX-50 over KEF Q150

Sensitivity	90 dB vs 86 dB	Play louder with same amount of amplification power
Low Frequency Response	50 Hz vs 51 Hz	Generates deeper bass
Height	225mm vs 303mm	Easier to fit in smaller spaces
Base Surface Area	386cm² vs 500cm²	Takes less floor space
Price per pair*	199USD vs 600USD	costs less (*prices may change depending on the seller, location and time)

Reasons to choose KEF Q150 over Cambridge Audio SX-50

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

Cambridge SX-50 vs KEF Q150 Specs Table

Detailed comparison of specifications

General	Cambridge Audio SX-50	KEF Q150
Brand	Cambridge Audio	KEF
Speaker Type	Bookshelf speakers	Bookshelf speakers
Power Range	10-100 watts	10-100 watts
Sensitivity	90 dB	86 dB
Impedance	8 ohms	8 ohms
Impedance	n/a	3.7 ohms
Frequency Response	50-22k Hz	51-28k Hz
Drivers
Woofer Quantity	1	1
Woofer Size	5.25"	5.25"
Woofer Composition	Treated paper	Aluminum
Woofer Surround Material	Rubber	Rubber
Tweeter Size	1"	1"
Tweeter Type	Dome	Dome
Aimable Tweeter	No	No
Midrange Driver	No	No
Crossover Frequency	n/a	2500Hz
Firing Direction	rear	rear
Physical Specs
Height	225.0mm (8.9")	303.0mm (11.9")
Width	161.0mm (6.3")	180.0mm (7.1")
Depth	240.0mm (9.4")	278.0mm (10.9")
Weight	3.00kg (6.6lbs)	5.60kg (12.3lbs)
Enclosure	Bass Reflex	Bass Reflex
Finish	MDF/Woodgrain vinyl	MDF/Vinyl-wrapped
Available Colors	Black	Black, Walnut, White
Mounting Bracket	No	No
Recommended Stand Height	28-31"	18-24"
Grille	Yes	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 Q150 costs roughly 3x 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	evenly matched	Much the same reach (50Hz vs 51Hz).
Amplifier needs	A	Cambridge SX-50 is more sensitive (90dB vs 86dB), 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 Q150 is bigger, which usually goes with fuller bass. Your room decides.
Expandability	depends	Neither adds bi-amping, a sub output or height drivers. KEF Q150 sits in a wider range (7 models), so a matched surround system is easier later.
Price	A	Cambridge SX-50 is cheaper - $199 against $600, about 67% less; arguably a different class.

A Cambridge SX-50 B KEF Q150
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 has the edge on paper, though the margin is not large. The rows marked "depends" may matter more to you than the score does. In a large or open-plan room, KEF Q150 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. If your amplifier is modest, vintage or valve-based, Cambridge SX-50 is the safer partner - the other will want more current or more watts to sound its best.

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.