In this review, we will be comparing KUBE 8b and S8, two Powered Subwoofer speakers from KEF and Audioengine. 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 KEF KUBE 8b and Audioengine S8 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.KEF KUBE 8band Audioengine S8 have the same driver set up: Both subwoofers have 1 x 8" drivers.
Frequency Response
KUBE 8b has a frequency range of 34-140 Hz whereas S8 has a frequency range of 27-180 Hz. With a minimum frequency of 27Hz, the S8 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 KEF KUBE 8b has a Acoustic Suspension type cabinet. 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. On the other hand the Audioengine S8 have Bass Reflex type enclosure. 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.
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 KEF KUBE 8b's and Audioengine S8's external dimensions. 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) whereas Audioengine S8 has external dimensions of 334.0 x 293.0 x 337.0mm (13-1/8 x 11-1/2 x 13-1/4inch).
Audioengine S8 is 3mm narrower and 2mm less deeper than KEF KUBE 8b but it is also 40mm taller.
Below you can see the front view size comparison of KEF KUBE 8b and Audioengine S8 in scale.
Comparison image of KEF KUBE 8b and Audioengine S8 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 KEF KUBE 8b is approximately 1003.4cm2 / 155.5inch2 and base area of the Audioengine S8 is approximately 987.4cm2 / 153.0inch2. The KUBE 8b requires 2% more surface area than the S8 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 KEF KUBE 8b weighs 11.36kg / 25lbs and the Audioengine S8 weighs 13.64kg / 30lbs. This makes the S8 20% heavier than the KUBE 8b.
Here is a comparison of how KUBE 8b and S8's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
What's in the Box of KEF KUBE 8b?
Here are the items that are included inside the box of KUBE 8b:
- Powered subwoofer
- 6.5-feet AC power cord
- Speaker-level input block
- User Manual
- Important Safety Information
- Warranty Information
What's in the Box of Audioengine S8?
Here are the items that come with the S8:
- Powered subwoofer
- 6-feet AC power cord
- 6.5-feet Stereo RCA cable
- 6.5-feet Stereo minijack audio cable
- Cloth subwoofer bag
- Cloth cable bag
- Quick Start Guide
- Audioengine brochure
 Height |
294mm
vs
334mm
|
Easier to fit in smaller spaces |
 Low Frequency Response |
27 Hz
vs
34 Hz
|
Generates deeper bass |
 High Frequency Response |
180 Hz
vs
140 Hz
|
Generates higher frequency |
 Base Surface Area |
987cm2
vs
1003cm2
|
Takes less floor space |
 Price per pair* |
349USD
vs
600USD
|
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.
Near-identical footprints. Audioengine S8 is 40mm taller.
| General |
KEF KUBE 8b |
Audioengine S8 |
| Brand |
KEF |
Audioengine |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
300 watts |
125 watts |
| Frequency Response |
34-140 Hz |
27-180 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
300-watt RMS |
125-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
8" |
8" |
| Woofer Composition |
|
Treated paper |
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
40-140 Hz |
n/a |
| Firing Direction |
front |
bottom |
Physical Specs |
|
|
| Height |
294.0mm (11.6") |
334.0mm (13.1") |
| Width |
296.0mm (11.7") |
293.0mm (11.5") |
| Depth |
339.0mm (13.3") |
337.0mm (13.3") |
| Weight |
11.36kg (25lbs) |
13.64kg (30lbs) |
| Enclosure |
Acoustic Suspension |
Bass Reflex |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
2 Years |
3 Years |
| Labor Warranty |
2 Years |
3 Years |
A sealed subwoofer against a ported 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 | Audioengine S8 goes deeper - 27Hz against 34Hz. A real difference, though most music has little content below 34Hz. |
| Amplifier power | A | KEF KUBE 8b has the bigger amplifier - 300W against 125W RMS, about 3.8dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | evenly matched | Near-identical radiating area (8" against 8"). |
| Enclosure | depends | 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; Audioengine S8 is ported - a ported box gives more output low down for its size, at the cost of a steeper roll-off below tuning. Neither is better in the abstract; ported tends to suit films and sealed tends to suit music, and both generalisations have exceptions. |
| Driver placement | depends | KEF KUBE 8b fires front and Audioengine S8 fires down. A down-firing driver is more forgiving of a grille-less look and of a hard floor; a front-firing one is the safer choice on a thick carpet or a suspended timber floor. |
| Warranty | B | Audioengine S8 carries 3 years on parts against 2 years. A subwoofer amplifier works harder than anything else in the system, so this is not a throwaway line. |
| Price | B | Audioengine S8 costs less - $349 against $600, about 42% less. |
A KEF KUBE 8b B Audioengine S8
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?
Audioengine S8 has the edge on paper, though not by much. The "depends" rows are more likely to decide this than the score is. Films or music? If this is mainly a home cinema, Audioengine S8 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. Two small subwoofers beat one big one in most rooms - a pair evens out the room modes in a way no single box can, whatever its specs. At $349 each, two Audioengine S8 cost about $698 against $600 for one of the other, which is worth a thought.
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.