In this review, we will be comparing Uni-Fi BS U5 Slim and Q150, two Passive Bookshelf speakers from ELAC and KEF.
Let's have a brief look at the main features
of ELAC Uni-Fi BS U5 Slim and KEF Q150 first before getting into our more
detailed comparison.
| Key Specs | ELAC Uni-Fi BS U5 Slim | KEF Q150 |
|---|
| Design | 3-way | 2-way |
|---|
| Uni-Q driver | — | 11th Generation Uni-Q |
|---|
| Tweeter | 1" soft dome | 1" Dome |
|---|
| Midrange | 4" | — |
|---|
| Woofer | 5.25" Aluminum | 5.25" Aluminum |
|---|
| Frequency response | 46-25k Hz | 51-28k Hz |
|---|
| Sensitivity | 85 dB | 86 dB |
|---|
| Impedance | 4 ohms | 8 ohms |
|---|
| Power range | 40-140 watts | 10-100 watts |
|---|
| Weight | 7.50kg / 16.5lbs | 5.60kg / 12.3lbs |
|---|
| Dimensions (H x W x D) | 13-3/8" x 7-1/16" x 12-7/8"
340.0 x 180.0 x 328.0mm | 11.9" x 7.0" x 10.9"
303.0 x 180.0 x 278.0mm |
|---|
What size room are the ELAC Uni-Fi BS U5 Slim 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* |
ELAC Uni-Fi BS U5 Slim |
KEF Q150 |
| Near-field |
Poor |
Average |
| Small Room |
Average |
Good |
| Mid-size Room |
Good |
Average |
| Large Room |
Average |
Poor |
| Very Large Room |
Poor |
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.
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Drivers
One of the fundamental differences between these two speakers is that Uni-Fi BS U5 Slim is a 3-way design whereas the Q150 is a 2-way speaker. 3-way designs utilize a midrange driver in addition to the tweeter and woofer on 2-way designs. Designing a crossover for a 3-way speaker is a complicated process and generally increases the overall cost of the speaker.
ELAC Uni-Fi BS U5 SlimKEF Q150
TweeterMidrangeWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
ELAC Uni-Fi BS U5 Slim |
KEF Q150 |
|
Driver Setup
|
3-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
1 x 4-inch |
- |
|
Woofer
|
1 x 5.25-inch
|
1 x 5.25-inch
|
Uni-Fi BS U5 Slim features a 1" soft dome Tweeter, a 4" Midrange and 1 x 5.25" Aluminum 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
Uni-Fi BS U5 Slim has a frequency range of 46-25k Hz whereas Q150 has a frequency range of 51-28k Hz. With a minimum frequency of 46Hz, the Uni-Fi BS U5 Slim can go significantly deeper on the low side and provide stronger bass compared to 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
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
Uni-Fi BS U5 Slim is a 4 ohms speaker compared to the Q150 which has a nominal impedance of 8 ohms. Lower impedance speakers, especially the ones that are rated at 4 ohms may put more pressure on the amplifier unit especially when played at high volume levels, so make sure the amp you pair with the Uni-Fi BS U5 Slim can provide this impedance level.
These two speakers also have different sensitivity levels. Uni-Fi BS U5 Slim sensitivity is rated at 85 dB and the Q150's is rated at 86 dB. This 1 dB difference makes the KEF Q150 a more sensitive speaker compared to ELAC Uni-Fi BS U5 Slim, 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. Staying
within that range gives nominal performance; driving the speaker beyond its maximum wattage can damage it.
Uni-Fi BS U5 Slim can handle a max power of 140 watts RMS, whereas Q150 has a max power handling value of 100 watts RMS, 40 watts less than the Uni-Fi BS U5 Slim.
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.
Input Type and Bi-Amping / Bi-Wiring
Uni-Fi BS U5 Slim features Post type posts and Q150 has a Post type posts. None of these speakers feature bi-amping/bi-wiring.
ELAC Uni-Fi BS U5 Slim's Post terminals
KEF Q150's Post terminals
Cabinet Type and Port Position
Both Uni-Fi BS U5 Slim 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.
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 ELAC Uni-Fi BS U5 Slim's and KEF Q150's external dimensions. ELAC Uni-Fi BS U5 Slim has external dimensions of 340.0 x 180.0 x 328.0mm (13-3/8 x 7-1/16 x 12-7/8inch) whereas KEF Q150 has external dimensions of 303.0 x 180.0 x 278.0mm (11.9 x 7.0 x 10.9inch).
Below you can see the front view size comparison of ELAC Uni-Fi BS U5 Slim and KEF Q150 in scale.
Comparison image of ELAC Uni-Fi BS U5 Slim 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 ELAC Uni-Fi BS U5 Slim is approximately 590.4cm2 / 91.5inch2 and base area of the KEF Q150 is approximately 500.4cm2 / 77.6inch2. The Uni-Fi BS U5 Slim requires 18% more surface area than the Q150 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 ELAC Uni-Fi BS U5 Slim 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 ELAC Uni-Fi BS U5 Slim weighs 7.50kg / 16.5lbs and the KEF Q150 weighs 5.60kg / 12.3lbs. This makes the Uni-Fi BS U5 Slim 34% heavier than the Q150.
Here is a comparison of how Uni-Fi BS U5 Slim and Q150's weights compare with the average, max and min weights in Passive Bookshelf class.
Weight
All Bookshelf Speakers
What's in the Box of ELAC Uni-Fi BS U5 Slim?
Here are the items that are included inside the box of Uni-Fi BS U5 Slim:
- 2 Bookshelf loudspeakers
- 2 Grilles
- Operating Instructions
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
 Max Input Power |
140 watts
vs
100 watts
|
Handle more power from your amplifier |
 Driver Setup |
3-way
vs
2-way
|
Have a dedicated mid-range driver |
 Low Frequency Response |
46 Hz
vs
51 Hz
|
Generates deeper bass |
 Sensitivity |
86 dB
vs
85 dB
|
Play louder with same amount of amplification power |
 Nominal Impedance |
8 ohms
vs
4 ohms
|
Less selective with amplifiers |
 High Frequency Response |
28k Hz
vs
25k Hz
|
Generates higher frequency |
 Height |
303mm
vs
340mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
500cm2
vs
590cm2
|
Takes less floor space |
 Price per pair* |
600USD
vs
735USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
ELAC Uni-Fi BS U5 Slim |
KEF Q150 |
| Brand |
ELAC |
KEF |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
40-140 watts |
10-100 watts |
| Sensitivity |
85 dB |
86 dB |
| Impedance |
4 ohms |
8 ohms |
| Impedance |
n/a |
3.7 ohms |
| Frequency Response |
46-25k Hz |
51-28k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
5.25" |
5.25" |
| Woofer Composition |
Aluminum |
Aluminum |
| Woofer Surround Material |
Rubber |
Rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
soft dome |
Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
4" |
No |
| Crossover Frequency |
n/a |
2500Hz |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
340.0mm (13.4") |
303.0mm (11.9") |
| Width |
180.0mm (7.1") |
180.0mm (7.1") |
| Depth |
328.0mm (12.9") |
278.0mm (10.9") |
| Weight |
7.50kg (16.5lbs) |
5.60kg (12.3lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
MDF/Vinyl |
MDF/Vinyl-wrapped |
| Available Colors |
Black |
Black, Walnut, White |
| Mounting Bracket |
No |
No |
| Recommended Stand Height |
24-31" |
18-24" |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
No |
No |
Other |
|
|
| Parts Warranty |
3 Years |
5 Years |
| Labor Warranty |
3 Years |
5 Years |
No single best speaker here - they are built to different priorities, and the right one depends on your room, your amplifier and what you listen to.
| Area | Better | Why |
|---|
| Bass |
A |
ELAC Uni-Fi BS U5 Slim digs deeper - 46Hz against 51Hz. A subwoofer would even that out. |
| Amplifier needs |
evenly matched |
Similar sensitivity (85dB vs 86dB) - both want much the same power. |
| Amplifier match |
B |
KEF Q150 is the easier load at 8 ohms; the other is 4 ohms and wants an amplifier rated for it. |
| Headroom |
A |
ELAC Uni-Fi BS U5 Slim takes more power (140W vs 100W) - more in hand in a big room. |
| Size |
depends |
KEF Q150 is easier to place; ELAC Uni-Fi BS U5 Slim is bigger, which usually goes with fuller bass. Your room decides. |
| Price |
B |
KEF Q150 is cheaper - $600 against $735, about 18% less. |
A ELAC Uni-Fi BS U5 Slim
B KEF Q150
depends neither is better in the abstract - it turns on your room, placement 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?
The usual trade-off: ELAC Uni-Fi BS U5 Slim measures better, KEF Q150 costs about 18% less. Whether that gap is worth the money is the call only you can make - and in a normal room it is often smaller than the numbers suggest. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 51Hz anyway, which makes the cheaper KEF Q150 much easier to justify. Match it to your room: we rate ELAC Uni-Fi BS U5 Slim the better fit for a mid-size room and a large room, and KEF Q150 for near-field listening and a small room.
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.