In this review, we will be comparing Alpha iQ and LS50 Wireless 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 LS50 Wireless II first before getting into our more
detailed comparison.
| Key Specs | PSB Alpha iQ | KEF LS50 Wireless II |
|---|
| Brand | PSB
Canada · founded 1972 | KEF
United Kingdom · founded 1961 |
|---|
| Design | 2-way | 2-way |
|---|
| Built-in amplifier | 180-watt RMS | 380-watt RMS (760-watt peak) |
|---|
| Uni-Q driver | — | 12th Generation Uni-Q |
|---|
| Tweeter | 0.75" Hard-Dome | 1" Hard-Dome |
|---|
| Woofer | 4" Polypropylene | 5.25" |
|---|
| Frequency response | 64-20kHz | 45-28k Hz |
|---|
| Max depth / sample rate | 24-bit / 192 kHz | Yes / 384 kHz |
|---|
| Bluetooth | Built-in | Built-in |
|---|
| App control | Yes | Yes |
|---|
| Weight | 7.36kg / 16.2lbs | 20.10kg / 44.2lbs |
|---|
| Dimensions (H x W x D) | 9.7" x 5.6" x 7.6"
246.0 x 145.0 x 192.0mm | 10.9375" x 7.875" x 12.6875"
277.8 x 200.0 x 322.3mm |
|---|
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 LS50 Wireless II are 2-way speakers.
PSB Alpha iQKEF LS50 Wireless II
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 LS50 Wireless II |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
0.75-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 4-inch
|
1 x 5.25-inch
|
Alpha iQ features a 0.75" aluminum Hard-Dome Tweeter and 1 x 4" Polypropylene Woofer. On the other hand, the LS50 Wireless II features a 1" Aluminum Hard-Dome Tweeter and 1 x 5.25" Woofer.
Frequency Response
Alpha iQ has a frequency range of 64-20kHz whereas LS50 Wireless II has a frequency range of 45-28k Hz. With a minimum frequency of 45Hz, the LS50 Wireless II 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 LS50 Wireless 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.
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 LS50 Wireless II'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 LS50 Wireless II has external dimensions of 277.8 x 200.0 x 322.3mm (10.9375 x 7.875 x 12.6875inch).
KEF LS50 Wireless II is clearly the larger of the two speakers. Its body is 55mm wider, 31.8mm taller and 130.3mm deeper than PSB Alpha iQ.
Below you can see the front view size comparison of PSB Alpha iQ and KEF LS50 Wireless II in scale.
Comparison image of PSB Alpha iQ and KEF LS50 Wireless 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 LS50 Wireless II is approximately 644.6cm2 / 99.9inch2. The Alpha iQ requires 57% less surface area than the LS50 Wireless II 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 LS50 Wireless 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 LS50 Wireless II weighs 20.10kg / 44.2lbs. This makes the LS50 Wireless II 173% heavier than the Alpha iQ.
Here is a comparison of how Alpha iQ and LS50 Wireless 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 LS50 Wireless II?
Here are the items that come with the LS50 Wireless II:
- 2 Wireless powered speakers
- Two 6.5' AC power cords
- 10' Cat-6 interconnect speaker cable
- Remote control
- 2 \"AAA\" batteries
- Quick Start Guide
- Important Safety Information
- Warranty Information
 Height |
246mm
vs
277mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
278cm2
vs
644cm2
|
Takes less floor space |
 Price per pair* |
1499USD
vs
2999USD
|
costs less (*prices may change depending on the seller, location and time) |
 Phono Input |
Yes
vs
No
|
Connect your turntable directly |
 Headphone Output |
Yes
vs
No
|
Connect your headphone |
 Woofer Size |
5.25 inches
vs
4 inches
|
Larger woofer |
|
Low Frequency Response |
45 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 |
| General |
PSB Alpha iQ |
KEF LS50 Wireless II |
| Brand |
PSB |
KEF |
| Speaker Type |
Powered Stereo Speakers |
Powered Stereo Speakers |
| Frequency Response |
64-20kHz |
45-28k Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
180-watt RMS |
380-watt RMS |
| Watts Peak (Max) |
n/a |
760-watt RMS |
| Max Bit Depth |
24-bit |
Yes |
| Max Sample Rate |
192 kHz |
384 kHz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
4" |
5.25" |
| Woofer Composition |
Polypropylene |
|
| Tweeter Size |
0.75" |
1" |
| 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") |
277.8mm (10.9") |
| Width |
145.0mm (5.7") |
200.0mm (7.9") |
| Depth |
192.0mm (7.6") |
322.3mm (12.7") |
| Weight |
7.36kg (16.2lbs) |
20.10kg (44.2lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Available Colors |
Matte Black,Matte White,Tangerine Yellow,Midnight Blue |
n/a |
| Mounting Bracket |
No |
|
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Aux Inputs |
3.5mm |
3.5mm |
| USB Port |
USB-A (connect a thumb drive for music playback) |
Service only |
| Phone Input |
Yes |
No |
| Subwoofer Output |
Wired |
mono-RCA |
| Digital Input |
Optical, HDMI |
1 |
| HDMI Input |
eARC |
eARC |
| Headphone Jack |
Yes |
No |
| Ethernet Port |
Yes |
Yes |
Other |
|
|
| Parts Warranty |
1 year |
3 Year w/ registration |
| Labor Warranty |
1 year |
3 Year w/ registration |
These sit in different price classes - KEF LS50 Wireless II costs roughly 2x what PSB Alpha iQ 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 LS50 Wireless II digs deeper - 45Hz against 64Hz. |
| Built-in power | B | KEF LS50 Wireless II has the bigger amplifier (380W vs 180W RMS). |
| Connections | depends | PSB Alpha iQ adds phono; KEF LS50 Wireless II adds Wi-Fi. |
| Size | depends | PSB Alpha iQ is easier to place; KEF LS50 Wireless II is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | depends | PSB Alpha iQ: a sub output; KEF LS50 Wireless II: a sub output. |
| Price | A | PSB Alpha iQ is cheaper - $1,499 against $2,999, about 50% less; arguably a different class. |
A PSB Alpha iQ B KEF LS50 Wireless II
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 LS50 Wireless II measures better, PSB Alpha iQ costs about about 100% 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 64Hz anyway, which makes the cheaper PSB Alpha iQ much easier to justify. In a large or open-plan room, KEF LS50 Wireless II has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, PSB Alpha iQ 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.