In this review, we will be comparing Alpha iQ and LSX, two Powered Bookshelf speakers from PSB and KEF. Being Powered speakers, they both have built-in amplifiers so you don't need an external power amp or an integrated amp to power them.
Let's have a brief look at the main features
of PSB Alpha iQ and KEF LSX first before getting into our more
detailed comparison.
| Key Specs | PSB Alpha iQ | KEF LSX |
|---|
| Brand | PSB
Canada · founded 1972 | KEF
United Kingdom · founded 1961 |
|---|
| Design | 2-way | 2-way |
|---|
| Built-in amplifier | 180-watt RMS | 200-watt RMS |
|---|
| Uni-Q driver | — | 11th Generation Uni-Q |
|---|
| Tweeter | 0.75" Hard-Dome | 0.75" Hard-Dome |
|---|
| Woofer | 4" Polypropylene | 4.5" Magnesium/Aluminium alloy |
|---|
| Frequency response | 64-20kHz | 59-28k Hz |
|---|
| Max depth / sample rate | 24-bit / 192 kHz | 24-bit / 96 kHz |
|---|
| Bluetooth | Built-in | Built-in 4.2 |
|---|
| App control | Yes | Yes |
|---|
| Weight | 7.36kg / 16.2lbs | 3.50kg / 7.7lbs |
|---|
| Dimensions (H x W x D) | 9.7" x 5.6" x 7.6"
246.0 x 145.0 x 192.0mm | 9.4375" x 6.125" x 7.1"
239.7 x 155.6 x 180mm |
|---|
The sections below take each area in turn: drivers, frequency response, physical size and what you get in the box.
Drivers
Both Alpha iQ and LSX are 2-way speakers.
PSB Alpha iQKEF LSX
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 Alpha iQ |
KEF LSX |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
0.75-inch
|
0.75-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 4-inch
|
1 x 4.5-inch
|
Alpha iQ features a 0.75" aluminum Hard-Dome Tweeter and 1 x 4" Polypropylene Woofer. On the other hand, the LSX features a 0.75" Aluminum Hard-Dome Tweeter and 1 x 4.5" Magnesium/Aluminium alloy Woofer.
Frequency Response
Alpha iQ has a frequency range of 64-20kHz whereas LSX has a frequency range of 59-28k Hz. With a minimum frequency of 59Hz, the LSX can go significantly deeper on the low side and provide stronger bass compared to the Alpha iQ's min frequency of 64Hz.
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.
Cabinet Type and Port Position
Both Alpha iQ and LSX 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.
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 Alpha iQ's and KEF LSX's external dimensions. PSB Alpha iQ has external dimensions of 246.0 x 145.0 x 192.0mm (9.7 x -5.6 x 7.6 inch) whereas KEF LSX has external dimensions of 239.7 x 155.6 x 180mm (9.4375 x 6.125 x 7.1inch).
KEF LSX is 6.3mm shorter and 12mm less deeper than PSB Alpha iQ but it is also 10.6mm wider.
Below you can see the front view size comparison of PSB Alpha iQ and KEF LSX in scale.
Comparison image of PSB Alpha iQ and KEF LSX 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 Alpha iQ is approximately 278.0cm2 / 43.1inch2 and base area of the KEF LSX is approximately 280.1cm2 / 43.4inch2. The Alpha iQ requires 1% less surface area than the LSX 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 Alpha iQ and KEF LSX 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 Alpha iQ weighs 7.36kg / 16.2lbs and the KEF LSX weighs 3.50kg / 7.7lbs. This makes the Alpha iQ 110% heavier than the LSX.
Here is a comparison of how Alpha iQ and LSX's weights compare with the average, max and min weights in Powered Bookshelf class.
Weight
All Bookshelf Speakers
What's in the Box of KEF LSX?
Here are the items that come with the LSX:
- 2 Powered wireless audio speaker
- Two 6.5-feet AC power cords
- 10-feet Ethernet cable
- Remote control (CR2032 3V battery pre-installed)
- Maintenance Guide
- Specifications
- Warranty Information
- Important Safety Information
 Base Surface Area |
278cm2
vs
280cm2
|
Takes less floor space |
 Phono Input |
Yes
vs
No
|
Connect your turntable directly |
 HDMI Input |
eARC
vs
No
|
Connect HDMI sources directly |
 Headphone Output |
Yes
vs
No
|
Connect your headphone |
 Woofer Size |
4.5 inches
vs
4 inches
|
Larger woofer |
|
Low Frequency Response |
59 Hz
vs
64 Hz
|
Generates deeper bass |
 High Frequency Response |
28k Hz
vs
20k Hz
|
Generates higher frequency |
 Handheld Remote |
Yes
vs
No
|
Control the speaker by the included RC |
 Height |
239mm
vs
246mm
|
Easier to fit in smaller spaces |
 Price per pair* |
1250USD
vs
1499USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
PSB Alpha iQ |
KEF LSX |
| Brand |
PSB |
KEF |
| Speaker Type |
Powered Stereo Speakers |
Powered Stereo Speakers |
| Frequency Response |
64-20kHz |
59-28k Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
180-watt RMS |
200-watt RMS |
| Max Bit Depth |
24-bit |
24-bit |
| Max Sample Rate |
192 kHz |
96 kHz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
4" |
4.5" |
| Woofer Composition |
Polypropylene |
Magnesium/Aluminium alloy |
| Woofer Surround Material |
n/a |
Rubber |
| Tweeter Size |
0.75" |
0.75" |
| Tweeter Type |
Hard-Dome |
Hard-Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
246.0mm (9.7") |
239.7mm (9.4") |
| Width |
145.0mm (5.7") |
155.6mm (6.1") |
| Depth |
192.0mm (7.6") |
180.0mm (7.1") |
| Weight |
7.36kg (16.2lbs) |
3.50kg (7.7lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Available Colors |
Matte Black,Matte White,Tangerine Yellow,Midnight Blue |
Black, Olive Green, Gloss White |
| Mounting Bracket |
No |
No |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Aux Inputs |
3.5mm |
3.5mm |
| USB Port |
USB-A (connect a thumb drive for music playback) |
Charge only |
| Phone Input |
Yes |
No |
| Subwoofer Output |
Wired |
Wired |
| Digital Input |
Optical, HDMI |
Optical |
| HDMI Input |
eARC |
No |
| Headphone Jack |
Yes |
No |
| Ethernet Port |
Yes |
Yes |
Other |
|
|
| Parts Warranty |
1 year |
1 Year |
| Labor Warranty |
1 year |
1 Year |
A generation apart: PSB Alpha iQ is the newer design, against a 2018 model. Newer is not automatically better, but the older one is more likely to be discounted or near run-out.
| Area | Better | Why |
|---|
| Bass | B | KEF LSX digs deeper - 59Hz against 64Hz. A subwoofer would even that out. |
| Built-in power | evenly matched | Similar onboard amplification (180W vs 200W RMS). |
| Connections | A | PSB Alpha iQ adds HDMI and phono; KEF LSX adds Wi-Fi. |
| Size | depends | Similar cabinet size - neither is easier to fit. |
| Expandability | depends | PSB Alpha iQ: a sub output; KEF LSX: a sub output. |
| Price | B | KEF LSX is cheaper - $1,250 against $1,499, about 17% less. |
A PSB Alpha iQ B KEF LSX
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 a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 64Hz anyway, so judge these on the other rows instead.
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.