In this review, we will be comparing Q150 and Alpha P5, two Passive Bookshelf speakers from KEF and PSB.
Let's have a brief look at the main features
of KEF Q150 and PSB P5 first before getting into our more
detailed comparison.
| Key Specs | KEF Q150 | PSB P5 |
|---|
| Brand | KEF
United Kingdom · founded 1961 | PSB
Canada · founded 1972 |
|---|
| Design | 2-way | 2-way |
|---|
| Uni-Q driver | 11th Generation Uni-Q | — |
|---|
| Tweeter | 1" Dome | 0.75" Hard-Dome |
|---|
| Woofer | 5.25" Aluminum | 5.25" Polypropylene |
|---|
| Frequency response | 51-28k Hz | 55-21k Hz |
|---|
| Sensitivity | 86 dB | 89 dB |
|---|
| Impedance | 8 ohms | 8 ohms |
|---|
| Power range | 10-100 watts | 10-90 watts |
|---|
| Weight | 5.60kg / 12.3lbs | 4.61kg / 10.1lbs |
|---|
| Dimensions (H x W x D) | 11.9" x 7.0" x 10.9"
303.0 x 180.0 x 278.0mm | 11-3/8" x 6-3/4" x 10"
289.0 x 172.0 x 254.0mm |
|---|
What size room are the KEF Q150 and PSB P5 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 Q150 |
PSB P5 |
| 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 Q150 and Alpha P5 are 2-way speakers.
KEF Q150PSB P5
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 Q150 |
PSB P5 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
0.75-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5.25-inch
|
1 x 5.25-inch
|
Q150 features a 1" vented aluminum Dome Tweeter and 1 x 5.25" Aluminum Woofer with a Crossover frequency at 2500Hz. On the other hand, the Alpha P5 features a 0.75" anodized aluminum Hard-Dome Tweeter and 1 x 5.25" Polypropylene Woofer with a Crossover frequency at 2500Hz.
Frequency Response
Q150 has a frequency range of 51-28k Hz whereas Alpha P5 has a frequency range of 55-21k Hz. With a minimum frequency of 51Hz, the Q150 can go slightly deeper then the Alpha P5's min frequency of 55Hz.
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
Q150 and Alpha P5 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. Q150 sensitivity is rated at 86 dB and the Alpha P5's is at 89 dB. This 3 dB difference makes the PSB P5 a more sensitive speaker compared to KEF Q150, 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.
Q150 can handle a max power of 100 watts RMS, whereas Alpha P5 has a max power handling value of 90 watts RMS, 10 watts less than the Q150.
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
Q150 features 5-way post type posts and Alpha P5 has a 5-way post type posts. None of these speakers feature bi-amping/bi-wiring.
KEF Q150's Post terminals
PSB P5's 5-way post terminals
Cabinet Type and Port Position
Both Q150 and Alpha P5 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 KEF Q150's and PSB P5's external dimensions. KEF Q150 has external dimensions of 303.0 x 180.0 x 278.0mm (11.9 x 7.0 x 10.9inch) whereas PSB P5 has external dimensions of 289.0 x 172.0 x 254.0mm (11-3/8 x 6-3/4 x 10inch).
KEF Q150 is clearly the larger of the two speakers. Its body is 8mm wider, 14mm taller and 24mm deeper than PSB P5.
Below you can see the front view size comparison of KEF Q150 and PSB P5 in scale.
Comparison image of KEF Q150 and PSB P5 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 Q150 is approximately 500.4cm2 / 77.6inch2 and base area of the PSB P5 is approximately 436.9cm2 / 67.7inch2. The Q150 requires 15% more surface area than the Alpha P5 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 Q150 and PSB P5 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 Q150 weighs 5.60kg / 12.3lbs and the PSB P5 weighs 4.61kg / 10.1lbs. This makes the Q150 21% heavier than the Alpha P5.
Here is a comparison of how Q150 and Alpha P5's weights compare with the average, max and min weights in Passive Bookshelf class.
Weight
All Bookshelf Speakers
What's in the Box of KEF Q150?
Here are the items that are included inside the box of Q150:
- 2 Bookshelf loudspeakers
- 2 Foam port plugs
- 8 Self-adhesive rubber feet
- Owner's Manual
- Warranty Registration Card
What's in the Box of PSB P5?
Here are the items that come with the Alpha P5:
- 2 Bookshelf loudspeakers
- 2 Grilles
- 8 Self-adhesive rubber feet
- Quick Start Guide
- Warranty Card
 Max Input Power |
100 watts
vs
90 watts
|
Handle more power from your amplifier |
 Low Frequency Response |
51 Hz
vs
55 Hz
|
Generates deeper bass |
 High Frequency Response |
28k Hz
vs
21k Hz
|
Generates higher frequency |
 Sensitivity |
89 dB
vs
86 dB
|
Play louder with same amount of amplification power |
 Minimum Impedance |
4 ohms
vs
3.7 ohms
|
Very low impedance levels puts more pressure on amplifier |
 Height |
289mm
vs
303mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
436cm2
vs
500cm2
|
Takes less floor space |
 Price per pair* |
449USD
vs
600USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
KEF Q150 |
PSB Alpha P5 |
| Brand |
KEF |
PSB |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
10-100 watts |
10-90 watts |
| Sensitivity |
86 dB |
89 dB |
| Impedance |
8 ohms |
8 ohms |
| Impedance |
3.7 ohms |
4 ohms |
| Frequency Response |
51-28k Hz |
55-21k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
5.25" |
5.25" |
| Woofer Composition |
Aluminum |
Polypropylene |
| Woofer Surround Material |
Rubber |
Rubber |
| Tweeter Size |
1" |
0.75" |
| Tweeter Type |
Dome |
Hard-Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
2500Hz |
2500Hz |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
303.0mm (11.9") |
289.0mm (11.4") |
| Width |
180.0mm (7.1") |
172.0mm (6.8") |
| Depth |
278.0mm (10.9") |
254.0mm (10") |
| Weight |
5.60kg (12.3lbs) |
4.61kg (10.1lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
MDF/Vinyl-wrapped |
MDF, Wood-grain vinyl |
| Available Colors |
Black, Walnut, White |
Walnut,Black Ash |
| Mounting Bracket |
No |
No |
| Recommended Stand Height |
18-24" |
28-30" |
| 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 |
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 | KEF Q150 digs deeper - 51Hz against 55Hz. A subwoofer would even that out. |
| Amplifier needs | B | PSB P5 is more sensitive (89dB vs 86dB), so it goes louder on the same amplifier. |
| Headroom | evenly matched | Similar power handling (100W vs 90W). |
| Size | depends | Similar cabinet size - neither is easier to fit. |
| Price | B | PSB P5 is cheaper - $449 against $600, about 25% less. |
A KEF Q150 B PSB P5
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?
Neither runs away with it - they trade advantages. Let the "depends" rows and your own room settle it. If your amplifier is modest, vintage or valve-based, PSB P5 is the safer partner - the other will want more current or more watts to sound its best. Think about the whole system, not just the speakers: the roughly $151 saved by taking the cheaper pair would buy a subwoofer or a better amplifier, and either usually does more for the sound than the difference between these two.
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.