In this review, we will be comparing S6 and KUBE 8b, two Powered Subwoofer speakers from Audioengine 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 Audioengine S6 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 Audioengine S6and KEF KUBE 8b have a single woofer setup however the Audioengine S6's woofer is 6-inch whereas the KEF KUBE 8b features a 8-inch woofer.
Frequency Response
S6 has a frequency range of 33-132 Hz whereas KUBE 8b has a frequency range of 34-140 Hz. With a minimum frequency of 33Hz, the S6 can go slightly deeper then 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
Both Audioengine S6 and KEF KUBE 8b have Acoustic Suspension type cabinets. 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 Audioengine S6's and KEF KUBE 8b's external dimensions. Audioengine S6 has external dimensions of 250.0 x 221.0 x 281.0mm (9-13/16inch x 8-11/16inch x 11-1/16inch) 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).
KEF KUBE 8b is clearly the larger of the two speakers. Its body is 75mm wider, 44mm taller and 58mm deeper than Audioengine S6.
Size, drawn to scale
Both speakers 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 surface and pushed back to the same wall, so the deeper one visibly sticks out further.
KEF KUBE 8b needs about 62% more floor or shelf area. KEF KUBE 8b is 58mm deeper, so it stands that much further out from the wall. KEF KUBE 8b is 44mm taller.
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 Audioengine S6 is approximately 621.0cm2 / 96.3inch2 and base area of the KEF KUBE 8b is approximately 1003.4cm2 / 155.5inch2. The S6 requires 38% less surface area than the KUBE 8b 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 Audioengine S6 weighs 7.00kg / 15.4lbs and the KEF KUBE 8b weighs 11.36kg / 25lbs. This makes the KUBE 8b 62% heavier than the S6.
Here is a comparison of how S6 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 Audioengine S6?
Here are the items that are included inside the box of S6:
- Powered subwoofer
- Grille
- 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
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
 Low Frequency Response |
33 Hz
vs
34 Hz
|
Generates deeper bass |
 Height |
250mm
vs
294mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
621cm2
vs
1003cm2
|
Takes less floor space |
 Price per pair* |
299USD
vs
600USD
|
costs less (*prices may change depending on the seller, location and time) |
 Wireless Operation |
Optional
vs
No
|
Connect your subwoofer to your system wireless |
| Woofer Size |
8 inches
vs
6 inches
|
Larger woofer |
 High Frequency Response |
140 Hz
vs
132 Hz
|
Generates higher frequency |
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 8b needs about 62% more floor area. KEF KUBE 8b stands 58mm further into the room. KEF KUBE 8b is 44mm taller.
| General |
Audioengine S6 |
KEF KUBE 8b |
| Brand |
Audioengine |
KEF |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
140 watts |
300 watts |
| Frequency Response |
33-132 Hz |
34-140 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
140-watt RMS |
300-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
6" |
8" |
| Woofer Composition |
Treated paper |
|
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
n/a |
40-140 Hz |
| Firing Direction |
front |
front |
Physical Specs |
|
|
| Height |
250.0mm (9.8") |
294.0mm (11.6") |
| Width |
221.0mm (8.7") |
296.0mm (11.7") |
| Depth |
281.0mm (11.1") |
339.0mm (13.3") |
| Weight |
7.00kg (15.4lbs) |
11.36kg (25lbs) |
| Enclosure |
Acoustic Suspension |
Acoustic Suspension |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
3 Years |
2 Years |
| Labor Warranty |
3 Years |
2 Years |
Two quite different sizes of subwoofer. Room volume decides this more than anything else on the page: a big driver in a small room is wasted, and a small one in a large room is worked to death.
| Area | Better | Why |
|---|
| Bass depth | evenly matched | Effectively the same reach (33Hz vs 34Hz). |
| Amplifier power | B | KEF KUBE 8b has the bigger amplifier - 300W against 140W RMS, about 3.3dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | B | KEF KUBE 8b moves more air: 8" against 6" is 1.78x the cone area, not the 1.33x the diameters suggest. More area means the same output with less excursion, and less distortion with it. |
| Enclosure | evenly matched | Both are sealed designs, so they roll off in much the same way. |
| Wireless option | depends | Only Audioengine S6 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 | Audioengine S6 is about 47% 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 | A | Audioengine S6 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 | A | Audioengine S6 costs less - $299 against $600, about 50% less. |
A Audioengine S6 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?
KEF KUBE 8b is ahead, but on only 1 of the measured areas, and it costs about 101% more. Audioengine S6 is the sensible buy unless your room is large enough to need the extra. 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 $299 each, two Audioengine S6 cost about $598 against $600 for one of the other, which is worth a thought. If placement is the constraint - a corner, behind a sofa, under a desk - Audioengine S6 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.