In this review, we will be comparing KUBE 8b and C 912, two Powered Subwoofer speakers from KEF and Jamo. 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 Jamo C 912 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 KEF KUBE 8band Jamo C 912 have a single woofer setup however the KEF KUBE 8b's woofer is 8-inch whereas the Jamo C 912 features a 12-inch woofer.
Frequency Response
KUBE 8b has a frequency range of 34-140 Hz whereas C 912 has a frequency range of 29-125 Hz. With a minimum frequency of 29Hz, the C 912 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 Jamo C 912 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 Jamo C 912'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 Jamo C 912 has external dimensions of 461.0 x 358.0 x 507.0mm (18-1/8 x 14-1/16 x 19-15/16inch).
Jamo C 912 is clearly the larger of the two speakers. Its body is 62mm wider, 167mm taller and 168mm deeper than KEF KUBE 8b.
Below you can see the front view size comparison of KEF KUBE 8b and Jamo C 912 in scale.
Comparison image of KEF KUBE 8b and Jamo C 912 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 Jamo C 912 is approximately 1815.1cm2 / 281.3inch2. The KUBE 8b requires 45% less surface area than the C 912 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 KEF KUBE 8b weighs 11.36kg / 25lbs and the Jamo C 912 weighs 18.98kg / 41.8lbs. This makes the C 912 67% heavier than the KUBE 8b.
Here is a comparison of how KUBE 8b and C 912'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 Jamo C 912?
Here are the items that come with the C 912:
- Powered subwoofer
- Grille
- 6-feet AC power cord
- User Manual
- Important Safety Instructions
- Warranty Information
 High Frequency Response |
140 Hz
vs
125 Hz
|
Generates higher frequency |
 Height |
294mm
vs
461mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1003cm2
vs
1815cm2
|
Takes less floor space |
 Woofer Size |
12 inches
vs
8 inches
|
Larger woofer |
| Low Frequency Response |
29 Hz
vs
34 Hz
|
Generates deeper bass |
 Price per pair* |
229USD
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 |
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.
Jamo C 912 needs about 81% more floor area. Jamo C 912 stands 168mm further into the room. Jamo C 912 is 167mm taller.
| General |
KEF KUBE 8b |
Jamo C 912 |
| Brand |
KEF |
Jamo |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
300 watts |
200 watts |
| Frequency Response |
34-140 Hz |
29-125 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
300-watt RMS |
200-watt RMS |
| Watts Peak (Max) |
n/a |
400-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
8" |
12" |
| Woofer Composition |
|
IMG |
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
40-140 Hz |
n/a |
| Firing Direction |
front |
front |
Physical Specs |
|
|
| Height |
294.0mm (11.6") |
461.0mm (18.1") |
| Width |
296.0mm (11.7") |
358.0mm (14.1") |
| Depth |
339.0mm (13.3") |
507.0mm (20") |
| Weight |
11.36kg (25lbs) |
18.98kg (41.8lbs) |
| Enclosure |
Acoustic Suspension |
Bass Reflex |
| Grille |
n/a |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
2 Years |
2 Years |
| Labor Warranty |
2 Years |
2 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 | Jamo C 912 goes deeper - 29Hz 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 200W RMS, about 1.8dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | B | Jamo C 912 moves more air: 12" against 8" is 2.25x the cone area, not the 1.5x the diameters suggest. More area means the same output with less excursion, and less distortion with it. |
| 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; Jamo C 912 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. |
| Wireless option | depends | Only Jamo C 912 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 | KEF KUBE 8b is about 65% 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. |
| Price | B | Jamo C 912 costs less - $229 against $600, about 62% less. |
A KEF KUBE 8b B Jamo C 912
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?
Jamo C 912 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, Jamo C 912 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 $229 each, two Jamo C 912 cost about $458 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.