In this review, we will be comparing Alpha P3 and Q150, two Passive Bookshelf speakers from PSB and KEF.
Let's have a brief look at the main features
of PSB P3 and KEF Q150 first before getting into our more
detailed comparison.
| Key Specs | PSB P3 | KEF Q150 |
|---|
| Brand | PSB
Canada · founded 1972 | KEF
United Kingdom · founded 1961 |
|---|
| Design | 2-way | 2-way |
|---|
| Uni-Q driver | — | 11th Generation Uni-Q |
|---|
| Tweeter | 0.75" Hard-Dome | 1" Dome |
|---|
| Woofer | 4.5" Polypropylene | 5.25" Aluminum |
|---|
| Frequency response | 57-21k Hz | 51-28k Hz |
|---|
| Sensitivity | 87 dB | 86 dB |
|---|
| Impedance | 8 ohms | 8 ohms |
|---|
| Power range | 10-80 watts | 10-100 watts |
|---|
| Weight | 2.23kg / 4.9lbs | 5.60kg / 12.3lbs |
|---|
| Dimensions (H x W x D) | 8-3/4" x 5-3/16" x 7-5/16"
223.0 x 132.0 x 186.0mm | 11.9" x 7.0" x 10.9"
303.0 x 180.0 x 278.0mm |
|---|
What size room are the PSB P3 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* |
PSB P3 |
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 Alpha P3 and Q150 are 2-way speakers.
PSB P3KEF 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 |
PSB P3 |
KEF Q150 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
0.75-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 4.5-inch
|
1 x 5.25-inch
|
Alpha P3 features a 0.75" anodized aluminum Hard-Dome Tweeter and 1 x 4.5" Polypropylene Woofer with a Crossover frequency at 3000Hz. 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
Alpha P3 has a frequency range of 57-21k Hz whereas Q150 has a frequency range of 51-28k Hz. With a minimum frequency of 51Hz, the Q150 can go significantly deeper on the low side and provide stronger bass compared to the Alpha P3's min frequency of 57Hz.
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
Alpha P3 and Q150 have the same Impedance of 8 ohms but where they differ is the sensitivity levels. Alpha P3 sensitivity is rated at 87 dB and the Q150's is at 86 dB. This 1 dB difference makes the PSB P3 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 P3 has a max power handling value of 80 watts RMS, 20 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
Alpha P3 features Post type posts and Q150 has a Post type posts. None of these speakers feature bi-amping/bi-wiring.
PSB P3's 5-way post terminals
KEF Q150's Post terminals
Cabinet Type and Port Position
Both Alpha P3 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 PSB P3's and KEF Q150's external dimensions. PSB P3 has external dimensions of 223.0 x 132.0 x 186.0mm (8-3/4 x 5-3/16 x 7-5/16inch) 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 48mm wider, 80mm taller and 92mm deeper than PSB P3.
Below you can see the front view size comparison of PSB P3 and KEF Q150 in scale.
Comparison image of PSB P3 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 PSB P3 is approximately 245.5cm2 / 38.1inch2 and base area of the KEF Q150 is approximately 500.4cm2 / 77.6inch2. The Alpha P3 requires 51% 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 PSB P3 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 PSB P3 weighs 2.23kg / 4.9lbs and the KEF Q150 weighs 5.60kg / 12.3lbs. This makes the Q150 151% heavier than the Alpha P3.
Here is a comparison of how Alpha P3 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 PSB P3?
Here are the items that are included inside the box of Alpha P3:
- 2 Bookshelf loudspeakers
- 2 Grilles
- 8 Self-adhesive rubber feet
- Quick Start Guide
- Warranty Card
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
 Sensitivity |
87 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 |
223mm
vs
303mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
245cm2
vs
500cm2
|
Takes less floor space |
 Price per pair* |
279USD
vs
600USD
|
costs less (*prices may change depending on the seller, location and time) |
 Max Input Power |
100 watts
vs
80 watts
|
Handle more power from your amplifier |
 Woofer Size |
5.25 inches
vs
4.5 inches
|
Larger woofer |
|
Low Frequency Response |
51 Hz
vs
57 Hz
|
Generates deeper bass |
 High Frequency Response |
28k Hz
vs
21k Hz
|
Generates higher frequency |
| General |
PSB Alpha P3 |
KEF Q150 |
| Brand |
PSB |
KEF |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
10-80 watts |
10-100 watts |
| Sensitivity |
87 dB |
86 dB |
| Impedance |
8 ohms |
8 ohms |
| Impedance |
4 ohms |
3.7 ohms |
| Frequency Response |
57-21k Hz |
51-28k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
4.5" |
5.25" |
| Woofer Composition |
Polypropylene |
Aluminum |
| Woofer Surround Material |
Rubber |
Rubber |
| Tweeter Size |
0.75" |
1" |
| Tweeter Type |
Hard-Dome |
Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
3000Hz |
2500Hz |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
223.0mm (8.8") |
303.0mm (11.9") |
| Width |
132.0mm (5.2") |
180.0mm (7.1") |
| Depth |
186.0mm (7.3") |
278.0mm (10.9") |
| Weight |
2.23kg (4.9lbs) |
5.60kg (12.3lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
MDF, Wood-grain vinyl |
MDF/Vinyl-wrapped |
| Available Colors |
Walnut,Black Ash |
Black, Walnut, White |
| Mounting Bracket |
No |
No |
| Recommended Stand Height |
28-30" |
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 |
These sit in different price classes - KEF Q150 costs roughly 2.2x what PSB P3 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 | KEF Q150 digs deeper - 51Hz against 57Hz. A subwoofer would even that out. |
| Amplifier needs | evenly matched | Similar sensitivity (87dB vs 86dB) - both want much the same power. |
| Headroom | B | KEF Q150 takes more power (100W vs 80W) - more in hand in a big room. |
| Size | depends | PSB P3 is easier to place; KEF Q150 is bigger, which usually goes with fuller bass. Your room decides. |
| Price | A | PSB P3 is cheaper - $279 against $600, about 54% less; arguably a different class. |
A PSB P3 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?
The usual trade-off: KEF Q150 measures better, PSB P3 costs about about 115% more% 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 57Hz anyway, which makes the cheaper PSB P3 much easier to justify. 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, PSB P3 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.