In this review, we will be comparing LSX II and Alpha AM5, two Powered Bookshelf speakers from KEF and PSB. 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 KEF LSX II and PSB Alpha AM5 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 KEF LSX II and PSB Alpha AM5 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 LSX II and Alpha AM5 are 2-way speakers.
Driver |
KEF LSX II |
PSB Alpha AM5 |
Driver Setup
|
2-way
|
2-way
|
Tweeter
|
0.75-inch
|
0.75-inch
|
Midrange
|
- |
- |
Woofer
|
1 x 4.5-inch
|
1 x 5.25-inch
|
LSX II features a 0.75" Aluminum Hard-Dome Tweeter and 1 x 4.5" Magnesium/Aluminium alloy Woofer . On the other hand, the Alpha AM5 features a 0.75" Aluminum Hard-Dome Tweeter and 1 x 5.25" Polypropylene Woofer .
Frequency Response
LSX II has a frequency range of 54-28k Hz whereas Alpha AM5 has a frequency range of 55-20k Hz. With a minimum frequency of 54Hz, the LSX II can go slightly deeper then the Alpha AM5's min frequency of 55Hz.
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 LSX II and Alpha AM5 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
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 KEF LSX II's and PSB Alpha AM5's external dimensions. KEF LSX II has external dimensions of 240 × 155 × 180 mm ( 9.5 × 6.1 × 7.1 inch) whereas PSB Alpha AM5 has external dimensions of 292.1 x 171.5 x 279.4mm ( 11.5 x 6.75 x 11inch) .
PSB Alpha AM5 is clearly the larger of the two speakers. Its body is 16.5mm wider, 52.1mm taller and 99.4mm deeper than KEF LSX II.
Below you can see the front view size comparison of KEF LSX II and PSB Alpha AM5 in scale.
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 LSX II is approximately 279.0cm2 / 43.2inch2 and base area of the PSB Alpha AM5 is approximately 479.2cm2 / 74.3inch2. The LSX II requires 42% less surface area than the Alpha AM5 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:
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 LSX II weighs 3.60kg / 7.9lbs and the PSB Alpha AM5 weighs 9.75kg / 21.5lbs. This makes the Alpha AM5 171% heavier than the LSX II.
Here is a comparison of how LSX II and Alpha AM5'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 are included inside the box of 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
What's in the Box of PSB Alpha AM5?
Here are the items that come with the Alpha AM5:
Powered speaker Passive speaker 2 Grilles AC power adapter (attached 45-inch DC cord) 4-feet AC power cord Remote control (PSR-1) 2 AAA batteries 8-feet Speaker cable 58-inch Stereo minijack cable 8 Self-adhesive rubber feet Connection Diagram Warranty Card
Low Frequency Response |
54 Hz
vs
55 Hz
|
Generates deeper bass |
High Frequency Response |
28k Hz
vs
20k Hz
|
Generates higher frequency |
App-Based Control |
Apple iOS, Android
vs
None
|
Control the speaker via an app |
Height |
240mm
vs
292mm
|
Easier to fit in smaller spaces |
Base Surface Area |
279cm2 (155x180mm)
vs
479cm2 (171x279mm)
|
Takes less floor space |
Ethernet Connection |
Yes
vs
No
|
High quality streaming over Ethernet |
USB Port |
USB-C (connects to your computer)
vs
No
|
USB port adds flexibility |
HDMI Input |
ARC
vs
No
|
Connect HDMI sources directly |
Subwoofer Output |
Wired
vs
No
|
Pair your speakers with external subwoofer |
Woofer Size |
5.25 inches
vs
4.5 inches
|
Larger woofer |
Price per pair* |
599USD
vs
1299USD
|
costs less (*prices may change depending on the seller, location and time) |
Phono Input |
Yes
vs
No
|
Connect your turntable directly |
General |
KEF LSX II |
PSB Alpha AM5 |
Brand |
KEF |
PSB |
Speaker Type |
Powered Stereo Speakers |
Powered Stereo Speakers |
Frequency Response |
54-28k Hz |
55-20k Hz |
Amplifier |
|
|
Watts RMS (Continuous) |
200-watt RMS |
100-watt RMS |
Max Bit Depth |
24-bit |
24-bit |
Max Sample Rate |
384 kHz |
48 kHz |
Drivers |
|
|
Woofer Quantity |
1 |
1 |
Woofer Size |
4.5" |
5.25" |
Woofer Composition |
Magnesium/Aluminium alloy |
Polypropylene |
Woofer Surround Material |
Rubber |
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 |
240.0mm (9.4") |
292.1mm (11.5") |
Width |
155.0mm (6.1") |
171.5mm (6.8") |
Depth |
180.0mm (7.1") |
279.4mm (11") |
Weight |
3.60kg (7.9lbs) |
9.75kg (21.5lbs) |
Enclosure |
Bass Reflex |
Bass Reflex |
Finish |
n/a |
MDF, Wood-grain vinyl |
Available Colors |
Carbon Black, Mineral White, Cobalt Blue, Lava Red, and Soundwave |
Matte Black, Matte White |
Mounting Bracket |
No |
No |
Grille |
n/a |
Yes |
Moisture Resistancy |
No |
No |
Connections |
|
|
Aux Inputs |
3.5mm |
3.5mm |
USB Port |
USB-C (connects to your computer) |
microUSB |
Phone Input |
No |
Yes |
Subwoofer Output |
Wired |
No |
Digital Input |
Optical |
Optical |
HDMI Input |
ARC |
No |
Headphone Jack |
No |
No |
Ethernet Port |
Yes |
No |
Other |
|
|
Parts Warranty |
1 Year |
1 Year |
Labor Warranty |
1 Year |
1 Year |