In this review, we will be comparing SB-4000 and KUBE 8b, two Powered Subwoofer speakers from SVS 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 SVS SB-4000 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 SVS SB-4000and KEF KUBE 8b have a single woofer setup however the SVS SB-4000's woofer is 13.5-inch whereas the KEF KUBE 8b features a 8-inch woofer.
Frequency Response
SB-4000 has a frequency range of 19-310 Hz whereas KUBE 8b has a frequency range of 34-140 Hz. With a minimum frequency of 19Hz, the SB-4000 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
Both SVS SB-4000 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 SVS SB-4000's and KEF KUBE 8b's external dimensions. SVS SB-4000 has external dimensions of 466.0 x 453.0 x 532.0mm (18-5/16 x 17-13/16 x 20-15/16inch) 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).
SVS SB-4000 is clearly the larger of the two speakers. Its body is 157mm wider, 172mm taller and 193mm deeper than KEF KUBE 8b.
Below you can see the front view size comparison of SVS SB-4000 and KEF KUBE 8b in scale.
Comparison image of SVS SB-4000 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 SVS SB-4000 is approximately 2410.0cm2 / 373.6inch2 and base area of the KEF KUBE 8b is approximately 1003.4cm2 / 155.5inch2. The SB-4000 requires 140% 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 SVS SB-4000 weighs 46.50kg / 102.3lbs and the KEF KUBE 8b weighs 11.36kg / 25lbs. This makes the SB-4000 309% heavier than the KUBE 8b.
Here is a comparison of how SB-4000 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 SVS SB-4000?
Here are the items that are included inside the box of SB-4000:
- Powered subwoofer
- Grille
- 6-feet AC power cord
- Remote control
- 4 Elastomer feet
- Owners Manual
- Important Safety Instructions
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 |
13.5 inches
vs
8 inches
|
Larger woofer |
| Low Frequency Response |
19 Hz
vs
34 Hz
|
Generates deeper bass |
 High Frequency Response |
310 Hz
vs
140 Hz
|
Generates higher frequency |
 App-Based Control |
iOS,Android
vs
None
|
Control the speaker via an app |
 Height |
294mm
vs
466mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1003cm2
vs
2410cm2
|
Takes less floor space |
 Price per pair* |
600USD
vs
1800USD
|
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.
SVS SB-4000 needs about 140% more floor area. SVS SB-4000 stands 193mm further into the room. SVS SB-4000 is 172mm taller.
| General |
SVS SB-4000 |
KEF KUBE 8b |
| Brand |
SVS |
KEF |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
1200 watts |
300 watts |
| Frequency Response |
19-310 Hz |
34-140 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
1200-watt RMS |
300-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
13.5" |
8" |
| Woofer Composition |
Composite/Glass Fiber |
|
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
n/a |
40-140 Hz |
| Firing Direction |
front |
front |
Physical Specs |
|
|
| Height |
466.0mm (18.3") |
294.0mm (11.6") |
| Width |
453.0mm (17.8") |
296.0mm (11.7") |
| Depth |
532.0mm (20.9") |
339.0mm (13.3") |
| Weight |
46.50kg (102.3lbs) |
11.36kg (25lbs) |
| Enclosure |
Acoustic Suspension |
Acoustic Suspension |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
5 Years |
2 Years |
| Labor Warranty |
5 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 | A | SVS SB-4000 goes deeper - 19Hz against 34Hz. Under 20Hz is felt more than heard - the bottom of a pipe organ and the bottom of a film mix. |
| Amplifier power | A | SVS SB-4000 has the bigger amplifier - 1200W against 300W RMS, about 6dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | A | SVS SB-4000 moves more air: 13.5" against 8" is 2.85x the cone area, not the 1.69x 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. |
| Cabinet size | depends | KEF KUBE 8b is about 74% 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 | SVS SB-4000 carries 5 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 | KEF KUBE 8b costs less - $600 against $1,800, about 67% less. |
A SVS SB-4000 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?
The usual trade-off: SVS SB-4000 measures better, KEF KUBE 8b costs about 67% less. In a normal room, placement will make a bigger difference than the gap between these two. 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 $600 each, two KEF KUBE 8b cost about $1,200 against $1,800 for one of the other, which is worth a thought. 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.