In this review, we will be comparing KUBE 8b and Sub Air, two Powered Subwoofer speakers from KEF and Focal. 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 Focal Sub Air 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.
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Drivers
The efficiency of a subwoofer is directly proportional to the total radiating are squared hence the woofer quantity and diameter.KEF KUBE 8band Focal Sub Air 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 Sub Air has a frequency range of 40-200 Hz. With a minimum frequency of 34Hz, the KUBE 8b can go significantly deeper on the low side and provide stronger bass compared to the Sub Air's min frequency of 40Hz.
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 Focal Sub Air 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 Focal Sub Air'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 Focal Sub Air has external dimensions of 410.0 x 362.0 x 162.0mm (16-1/8 x 14-1/4 x 6-3/8inch).
KEF KUBE 8b is 66mm narrower and 116mm shorter than Focal Sub Air but it is also 177mm deeper.
Below you can see the front view size comparison of KEF KUBE 8b and Focal Sub Air in scale.
Comparison image of KEF KUBE 8b and Focal Sub Air 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 Focal Sub Air is approximately 586.4cm2 / 90.9inch2. The KUBE 8b requires 71% more surface area than the Sub Air 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 Focal Sub Air weighs 7.73kg / 17lbs. This makes the KUBE 8b 47% heavier than the Sub Air.
Here is a comparison of how KUBE 8b and Sub Air'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 Focal Sub Air?
Here are the items that come with the Sub Air:
- Wireless powered subwoofer
- Wireless transmitter
- AC power adapter (attached 6-feet DC cord)
- AC power plug insert (2-prong)
- 8-feet AC power cord
- 4 Rubber feet
- 2 Brackets
- Four M4 x 10mm machine screws
- Four M4 x 17mm machine screws
- 4 Wood-screws
- 4 Wall-anchors
- User Manual
 Low Frequency Response |
34 Hz
vs
40 Hz
|
Generates deeper bass |
 Height |
294mm
vs
410mm
|
Easier to fit in smaller spaces |
 Price per pair* |
600USD
vs
1299USD
|
costs less (*prices may change depending on the seller, location and time) |
 High Frequency Response |
200k Hz
vs
140k Hz
|
Generates higher frequency |
 Base Surface Area |
586cm2
vs
1003cm2
|
Takes less floor space |
 Wireless Operation |
Yes
vs
No
|
Connect your subwoofer to your system wireless |
| General |
KEF KUBE 8b |
Focal Sub Air |
| Brand |
KEF |
Focal |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
300 watts |
110 watts |
| Frequency Response |
34-140 Hz |
40-200 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
300-watt RMS |
110-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
8" |
8" |
| Woofer Composition |
|
Cellulose Pulp |
| 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") |
410.0mm (16.1") |
| Width |
296.0mm (11.7") |
362.0mm (14.3") |
| Depth |
339.0mm (13.3") |
162.0mm (6.4") |
| Weight |
11.36kg (25lbs) |
7.73kg (17lbs) |
| Enclosure |
Acoustic Suspension |
Bass Reflex |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
2 Years |
3 Years |
| Labor Warranty |
2 Years |
3 Years |