In this review, we will be comparing Q SUB120 and KUBE 8b, two Powered Subwoofer speakers from Q Acoustics 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 Q Acoustics Q SUB120 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 Q Acoustics Q SUB120and KEF KUBE 8b have a single woofer setup however the Q Acoustics Q SUB120's woofer is 12-inch whereas the KEF KUBE 8b features a 8-inch woofer.
Frequency Response
Q SUB120 has a frequency range of 28-250 Hz whereas KUBE 8b has a frequency range of 34-140 Hz. With a minimum frequency of 28Hz, the Q SUB120 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 Q Acoustics Q SUB120 has a Infinite Baffle type cabinet. On the other hand the KEF KUBE 8b 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 Q Acoustics Q SUB120's and KEF KUBE 8b's external dimensions. Q Acoustics Q SUB120 has external dimensions of 400.0 x 400.0 x 432.0mm (15-3/4 x 15-3/4 x 17inch) 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).
Q Acoustics Q SUB120 is clearly the larger of the two speakers. Its body is 104mm wider, 106mm taller and 93mm deeper than KEF KUBE 8b.
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.
Q Acoustics Q SUB120 needs about 72% more floor or shelf area. Q Acoustics Q SUB120 is 93mm deeper, so it stands that much further out from the wall. Q Acoustics Q SUB120 is 106mm 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 Q Acoustics Q SUB120 is approximately 1728.0cm2 / 267.8inch2 and base area of the KEF KUBE 8b is approximately 1003.4cm2 / 155.5inch2. The Q SUB120 requires 72% 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 Q Acoustics Q SUB120 weighs 22.50kg / 49.5lbs and the KEF KUBE 8b weighs 11.36kg / 25lbs. This makes the Q SUB120 98% heavier than the KUBE 8b.
Here is a comparison of how Q SUB120 and KUBE 8b's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
 Woofer Size |
12 inches
vs
8 inches
|
Larger woofer |
| Low Frequency Response |
28 Hz
vs
34 Hz
|
Generates deeper bass |
 High Frequency Response |
250 Hz
vs
140 Hz
|
Generates higher frequency |
 Height |
294mm
vs
400mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1003cm2
vs
1728cm2
|
Takes less floor space |
 Price per pair* |
600USD
vs
799USD
|
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.
Q Acoustics Q SUB120 needs about 72% more floor area. Q Acoustics Q SUB120 stands 93mm further into the room. Q Acoustics Q SUB120 is 106mm taller.
| General |
Q Acoustics Q SUB120 |
KEF KUBE 8b |
| Brand |
Q Acoustics |
KEF |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
300 watts |
300 watts |
| Frequency Response |
28-250 Hz |
34-140 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
300-watt RMS |
300-watt RMS |
| Watts Peak (Max) |
600-watt RMS |
n/a |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
12" |
8" |
| Woofer Composition |
Paper composite |
|
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
n/a |
40-140 Hz |
| Firing Direction |
n/a |
front |
Physical Specs |
|
|
| Height |
400.0mm (15.7") |
294.0mm (11.6") |
| Width |
400.0mm (15.7") |
296.0mm (11.7") |
| Depth |
432.0mm (17") |
339.0mm (13.3") |
| Weight |
22.50kg (49.5lbs) |
11.36kg (25lbs) |
| Enclosure |
Infinite Baffle |
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 | Q Acoustics Q SUB120 goes deeper - 28Hz against 34Hz. A real difference, though most music has little content below 34Hz. |
| Amplifier power | evenly matched | Much the same amplifier (300W vs 300W RMS) - under 1dB apart. |
| Driver area | A | Q Acoustics Q SUB120 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 | evenly matched | Both are sealed designs, so they roll off in much the same way. |
| Cabinet size | depends | KEF KUBE 8b is about 57% 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 | Q Acoustics Q SUB120 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 $799, about 25% less. |
A Q Acoustics Q SUB120 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?
Q Acoustics Q SUB120 leads across most of the measured areas for a modest premium, so it is the easier pick if the budget stretches. KEF KUBE 8b is the one to take if it does not. 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.