In this review, we will be comparing Alpha S10 and KUBE 8b, two Powered Subwoofer speakers from PSB and KEF. Being Powered subwoofers, 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 S10 and KEF KUBE 8b first before getting into our more detailed comparison.
The sections below take each area in turn: driver and amplifier, frequency response, physical size and connectivity.
Drivers
The efficiency of a subwoofer is directly proportional to the total radiating are squared hence the woofer quantity and diameter.Both PSB Alpha S10and KEF KUBE 8b have a single woofer setup however the PSB Alpha S10's woofer is 10-inch whereas the KEF KUBE 8b features a 8-inch woofer.
Frequency Response
Alpha S10 has a frequency range of 28-150 Hz whereas KUBE 8b has a frequency range of 34-140 Hz. With a minimum frequency of 28Hz, the Alpha S10 can go significantly deeper on the low side and provide stronger bass compared to the KUBE 8b's min frequency of 34Hz.
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 Subwoofer class in our database.
Low Frequency
Subwoofer Speakers
High Frequency
Subwoofer Speakers
Cabinet Type
The PSB Alpha S10 has a Bass Reflex type cabinet. Bass Reflex type subwoofers (aka Ported, Vented or Reflex Port) have enclosures that uses a port, hole or vent cut into the cabinet. Ported designs are generally more efficient than the Sealed designs. On the other hand the KEF KUBE 8b have Acoustic Suspension type enclosure. Acoustic Suspension aka Sealed type subwoofers have enclosures that are sealed hence no ports or holes exists on the cabinet. Sealed designs helps to provide more accurate and tight bass responses compared to ported designs.
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 S10's and KEF KUBE 8b's external dimensions. PSB Alpha S10 has external dimensions of 358.0 x 358.0 x 472.0mm (14-1/16 x 14-1/16 x 18-9/16inch) whereas KEF KUBE 8b has external dimensions of 294.0 x 296.0 x 339.0mm (11-9/16 x 11-5/8 x 13-5/16inch).
PSB Alpha S10 is clearly the larger of the two speakers. Its body is 62mm wider, 64mm taller and 133mm deeper than KEF KUBE 8b.
Below you can see the front view size comparison of PSB Alpha S10 and KEF KUBE 8b in scale.
Comparison image of PSB Alpha S10 and KEF KUBE 8b 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 S10 is approximately 1689.8cm2 / 261.9inch2 and base area of the KEF KUBE 8b is approximately 1003.4cm2 / 155.5inch2. The Alpha S10 requires 68% more surface area than the KUBE 8b which gives it a small disadvantage on placement in tight spaces.
Weight Comparison The weight of a subwoofer may become an important factor if you need to move and reposition the unit often to find the optimal positioning, also known as 'Subwoofer Crawling'. The PSB Alpha S10 weighs 13.64kg / 30lbs and the KEF KUBE 8b weighs 11.36kg / 25lbs. This makes the Alpha S10 20% heavier than the KUBE 8b.
Here is a comparison of how Alpha S10 and KUBE 8b's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
What's in the Box of PSB Alpha S10?
Here are the items that are included inside the box of Alpha S10:
- Powered subwoofer
- Grille
- 5-feet AC power cord
- 4 Rubber feet
- 4 Spike feet
- 4 Hex-nuts
- Quick Start Guide
- Important Safety Instructions
- Warranty Information
What's in the Box of KEF KUBE 8b?
Here are the items that come with the KUBE 8b:
- Powered subwoofer
- 6.5-feet AC power cord
- Speaker-level input block
- User Manual
- Important Safety Information
- Warranty Information
 Woofer Size |
10 inches
vs
8 inches
|
Larger woofer |
| Low Frequency Response |
28 Hz
vs
34 Hz
|
Generates deeper bass |
 High Frequency Response |
150 Hz
vs
140 Hz
|
Generates higher frequency |
 Height |
294mm
vs
358mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1003cm2
vs
1689cm2
|
Takes less floor space |
 Price per pair* |
600USD
vs
699USD
|
costs less (*prices may change depending on the seller, location and time) |
Size, drawn to scale
Both subwoofers and both views share one scale, so everything here is directly comparable. Hover a box for its dimensions.
One scale for both, standing on the same floor and pushed back to the same wall, so the bigger one visibly takes more of the room.
PSB Alpha S10 needs about 68% more floor area. PSB Alpha S10 stands 133mm further into the room. PSB Alpha S10 is 64mm taller.
| General |
PSB Alpha S10 |
KEF KUBE 8b |
| Brand |
PSB |
KEF |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
150 watts |
300 watts |
| Frequency Response |
28-150 Hz |
34-140 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
150-watt RMS |
300-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
10" |
8" |
| Woofer Composition |
Polypropylene |
|
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
n/a |
40-140 Hz |
| Firing Direction |
front |
front |
Physical Specs |
|
|
| Height |
358.0mm (14.1") |
294.0mm (11.6") |
| Width |
358.0mm (14.1") |
296.0mm (11.7") |
| Depth |
472.0mm (18.6") |
339.0mm (13.3") |
| Weight |
13.64kg (30lbs) |
11.36kg (25lbs) |
| Enclosure |
Bass Reflex |
Acoustic Suspension |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
1 Year |
2 Years |
| Labor Warranty |
1 Year |
2 Years |
A ported subwoofer against a sealed one. That is the most consequential line on this page: it decides how the bass rolls off, how it behaves in a small room, and how much output you get for the size of the box.
| Area | Better | Why |
|---|
| Bass depth | A | PSB Alpha S10 goes deeper - 28Hz against 34Hz. A real difference, though most music has little content below 34Hz. |
| Amplifier power | B | KEF KUBE 8b has the bigger amplifier - 300W against 150W RMS, about 3dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | A | PSB Alpha S10 moves more air: 10" against 8" is 1.56x the cone area, not the 1.25x the diameters suggest. More area means the same output with less excursion, and less distortion with it. |
| Enclosure | depends | PSB Alpha S10 is ported - a ported box gives more output low down for its size, at the cost of a steeper roll-off below tuning; KEF KUBE 8b is sealed - a sealed box rolls off gently and is usually the easier one to integrate in a small or awkward room. Neither is better in the abstract; ported tends to suit films and sealed tends to suit music, and both generalisations have exceptions. |
| Cabinet size | depends | KEF KUBE 8b is about 51% smaller by volume. In a subwoofer that is a real trade rather than a preference: box volume is how you get output low down without a bigger amplifier. |
| Warranty | B | KEF KUBE 8b carries 2 years on parts against 1 years. A subwoofer amplifier works harder than anything else in the system, so this is not a throwaway line. |
| Price | B | KEF KUBE 8b costs less - $600 against $699, about 14% less. |
A PSB Alpha S10 B KEF KUBE 8b
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 subwoofers 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 your room size and where the box can actually stand settle it. Films or music? If this is mainly a home cinema, PSB Alpha S10 will hit harder for the money; if it is mainly for music in a normal-sized room, KEF KUBE 8b is usually the easier one to make sound right. If placement is the constraint - a corner, behind a sofa, under a desk - KEF KUBE 8b is the one that will actually go there, and a well-placed small subwoofer beats a badly-placed big one every time.
One thing outweighs everything above: where the subwoofer stands. Room modes can add or remove 10dB or more at a given seat, which is far larger than any difference on this page. Before spending more, try the sub in two or three positions - the crawl test, where you put it in the listening seat and crawl the room to find where the bass sounds best, costs nothing and usually beats an upgrade.