In this review, we will be comparing Alpha iQ and LSX II, 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 II first before getting into our more
detailed comparison.
In the following sections, we will get into more detail in order to better understand how the PSB Alpha iQ and KEF LSX II compare and hopefully end up with enough arguments to decide which one of these loudspeakers is the better choice for you.
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Drivers
Both Alpha iQ and LSX II are 2-way speakers.
| Driver |
PSB Alpha iQ |
KEF LSX II |
|
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 II 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 II has a frequency range of 54-28k Hz. With a minimum frequency of 54Hz, the LSX II can go significantly deeper on the low side and provide stronger bass compared to the Alpha iQ's min frequency of 64Hz.
Below graphs depict how these two speakers compare with the max, min and average values of the Min and Max Frequencies of other speakers in the Bookshelf class in our database.
Low Frequency
Bookshelf Speakers
High Frequency
Bookshelf Speakers
None of these speakers achieves full range experience which is commonly agreed as 20Hz-20kHz. In order to achieve lower lows / deeper bass, we recommend you pair these with a subwoofer. Visit our Powered Subwoofers section to find out more about the available options.
Cabinet Type and Port Position
Both Alpha iQ and LSX II 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 LSX II Port
Physical Specs
Size of a speaker can sometimes become 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 II's external dimensions. PSB Alpha iQ has external dimensions of 246 x 145 x 92mm ( 9.7 x -5.6 x 7.6 inch ) whereas KEF LSX II has external dimensions of 240 × 155 × 180 mm ( 9.5 × 6.1 × 7.1 inch) .
KEF LSX II is 6mm shorter and 12mm less deeper than PSB Alpha iQ but it is also 10mm wider.
Below you can see the front view size comparison of PSB Alpha iQ and KEF LSX II in scale.
Comparison image of PSB Alpha iQ and KEF LSX II 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 II is approximately 279.0cm2 / 43.2inch2. The Alpha iQ requires 0% less surface area than the LSX II which gives it a small advantage on placement in tight spaces.
Here is an 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 II 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 II weighs 3.60kg / 7.9lbs. This makes the Alpha iQ 104% heavier than the LSX II.
Here is a comparison of how Alpha iQ and LSX II'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 II?
Here are the items that come with the LSX II:
2 Wireless powered speakersTwo 6.5-feet AC power cords10-feet Cat-6 interconnect speaker cableRemote control2 AAA batteries Quick Start Guide Important Safety Information Warranty Information Maintenance Guide
 Base Surface Area |
278cm2 (145x192mm)
vs
279cm2 (155x180mm)
|
Takes less floor space |
 Phono Input |
Yes
vs
No
|
Connect your turntable directly |
 Headphone Output |
Yes
vs
No
|
Connect your headphone |
 Woofer Size |
4.5 inches
vs
4 inches
|
Larger woofer |
| Low Frequency Response |
54 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 |
240mm
vs
246mm
|
Easier to fit in smaller spaces |
 Price per pair* |
1299USD
vs
1499USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
PSB Alpha iQ |
KEF LSX II |
| Brand |
PSB |
KEF |
| Speaker Type |
Powered Stereo Speakers |
Powered Stereo Speakers |
| Frequency Response |
64-20kHz |
54-28k Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
180-watt RMS |
200-watt RMS |
| Max Bit Depth |
24-bit |
24-bit |
| Max Sample Rate |
192 kHz |
384 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") |
240.0mm (9.4") |
| Width |
145.0mm (5.7") |
155.0mm (6.1") |
| Depth |
192.0mm (7.6") |
180.0mm (7.1") |
| Weight |
7.36kg (16.2lbs) |
3.60kg (7.9lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Available Colors |
Matte Black,Matte White,Tangerine Yellow,Midnight Blue |
Carbon Black, Mineral White, Cobalt Blue, Lava Red, and Soundwave |
| 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) |
USB-C (connects to your computer) |
| Phone Input |
Yes |
No |
| Subwoofer Output |
Wired |
Wired |
| Digital Input |
Optical, HDMI |
Optical |
| HDMI Input |
eARC |
ARC |
| Headphone Jack |
Yes |
No |
| Ethernet Port |
Yes |
Yes |
Other |
|
|
| Parts Warranty |
1 year |
1 Year |
| Labor Warranty |
1 year |
1 Year |