In this review, we will be comparing Alpha S8 and KUBE 10b, 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 S8 and KEF KUBE 10b 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 S8and KEF KUBE 10b have a single woofer setup however the PSB Alpha S8's woofer is 8-inch whereas the KEF KUBE 10b features a 10-inch woofer.
Frequency Response
Alpha S8 has a frequency range of 35-150 Hz whereas KUBE 10b has a frequency range of 24-140 Hz. With a minimum frequency of 24Hz, the KUBE 10b can go significantly deeper on the low side and provide stronger bass compared to the Alpha S8's min frequency of 35Hz.
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 S8 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 10b 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 S8's and KEF KUBE 10b's external dimensions. PSB Alpha S8 has external dimensions of 318.0 x 293.0 x 413.0mm (12-1/2 x 11-1/2 x 16-1/4inch) whereas KEF KUBE 10b has external dimensions of 372.0 x 356.0 x 397.0mm (14-5/8 x 14 x 15-5/8inch).
PSB Alpha S8 is 63mm narrower and 54mm shorter than KEF KUBE 10b but it is also 16mm deeper.
Below you can see the front view size comparison of PSB Alpha S8 and KEF KUBE 10b in scale.
Comparison image of PSB Alpha S8 and KEF KUBE 10b 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 S8 is approximately 1210.1cm2 / 187.6inch2 and base area of the KEF KUBE 10b is approximately 1413.3cm2 / 219.1inch2. The Alpha S8 requires 14% less surface area than the KUBE 10b which gives it a small advantage 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 S8 weighs 9.55kg / 21lbs and the KEF KUBE 10b weighs 17.50kg / 38.5lbs. This makes the KUBE 10b 83% heavier than the Alpha S8.
Here is a comparison of how Alpha S8 and KUBE 10b'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 S8?
Here are the items that are included inside the box of Alpha S8:
- 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 10b?
Here are the items that come with the KUBE 10b:
- Powered subwoofer
- 6.5-feet AC power cord
- Speaker-level input block
- User Manual
- Important Safety Information
- Warranty Information
 High Frequency Response |
150 Hz
vs
140 Hz
|
Generates higher frequency |
 Height |
318mm
vs
372mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1210cm2
vs
1413cm2
|
Takes less floor space |
 Price per pair* |
549USD
vs
750USD
|
costs less (*prices may change depending on the seller, location and time) |
 Woofer Size |
10 inches
vs
8 inches
|
Larger woofer |
| Low Frequency Response |
24 Hz
vs
35 Hz
|
Generates deeper bass |
 Wireless Operation |
Optional
vs
No
|
Connect your subwoofer to your system wireless |
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.
KEF KUBE 10b needs about 17% more floor area. PSB Alpha S8 stands 16mm further into the room. KEF KUBE 10b is 54mm taller.
| General |
PSB Alpha S8 |
KEF KUBE 10b |
| Brand |
PSB |
KEF |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
150 watts |
300 watts |
| Frequency Response |
35-150 Hz |
24-140 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
150-watt RMS |
300-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
8" |
10" |
| 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 |
318.0mm (12.5") |
372.0mm (14.6") |
| Width |
293.0mm (11.5") |
356.0mm (14") |
| Depth |
413.0mm (16.3") |
397.0mm (15.6") |
| Weight |
9.55kg (21lbs) |
17.50kg (38.5lbs) |
| 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 | B | KEF KUBE 10b goes deeper - 24Hz against 35Hz. That gap covers the lowest notes of a five-string bass and a concert bass drum. |
| Amplifier power | B | KEF KUBE 10b 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 | B | KEF KUBE 10b 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 S8 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 10b 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. |
| Wireless option | depends | Only KEF KUBE 10b offers a wireless link (as a paid option). It decides where the sub can go if you cannot run a cable, and is worth nothing if you can. |
| Cabinet size | depends | PSB Alpha S8 is about 27% 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 10b 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 | A | PSB Alpha S8 costs less - $549 against $750, about 27% less. |
A PSB Alpha S8 B KEF KUBE 10b
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?
The usual trade-off: KEF KUBE 10b measures better, PSB Alpha S8 costs about 27% less. In a normal room, placement will make a bigger difference than the gap between these two. Films or music? If this is mainly a home cinema, PSB Alpha S8 will hit harder for the money; if it is mainly for music in a normal-sized room, KEF KUBE 10b is usually the easier one to make sound right.
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.