In this review, we will be comparing Kube 12 MIE and Monitor XT12, two Powered Subwoofer speakers from KEF and Polk Audio. 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 12 MIE and Polk Monitor XT12 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.KEF Kube 12 MIEand Polk Monitor XT12 have the same driver set up: Both subwoofers have 1 x 12" drivers.
Frequency Response
Kube 12 MIE has a frequency range of 22-140 Hz whereas Monitor XT12 has a frequency range of 24-160 Hz. With a minimum frequency of 22Hz, the Kube 12 MIE can go slightly deeper then the Monitor XT12's min frequency of 24Hz.
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 12 MIE 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 Polk Monitor XT12 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 12 MIE's and Polk Monitor XT12's external dimensions. KEF Kube 12 MIE has external dimensions of 410 x 393 x 410 mm (16.1 x 15.5 x 16.1 in) whereas Polk Monitor XT12 has external dimensions of 418.0 x 408.0 x 485.0mm (16-7/16inch x 16-1/16inch x 19-1/16inch).
Polk Monitor XT12 is clearly the larger of the two speakers. Its body is 15mm wider, 8mm taller and 75mm deeper than KEF Kube 12 MIE.
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 12 MIE is approximately 1611.3cm2 / 249.8inch2 and base area of the Polk Monitor XT12 is approximately 1978.8cm2 / 306.7inch2. The Kube 12 MIE requires 19% less surface area than the Monitor XT12 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 12 MIE weighs 18.60kg / 40.9lbs and the Polk Monitor XT12 weighs 17.73kg / 39lbs. This makes the Kube 12 MIE 5% heavier than the Monitor XT12.
Here is a comparison of how Kube 12 MIE and Monitor XT12'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 12 MIE?
Here are the items that are included inside the box of Kube 12 MIE:
- Kube 12 MIE subwoofer
- Power cord
- Euroblock speaker level connector
- User manual and warranty information
What's in the Box of Polk Monitor XT12?
Here are the items that come with the Monitor XT12:
- Black powered subwoofer
- 6.5-feet AC power cord
- Grille
- Owners Manual
- Online registration card
 Low Frequency Response |
22 Hz
vs
24 Hz
|
Generates deeper bass |
 Height |
410mm
vs
418mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1611cm2
vs
1978cm2
|
Takes less floor space |
 Wireless Operation |
Optional
vs
No
|
Connect your subwoofer to your system wireless |
 High Frequency Response |
160 Hz
vs
140 Hz
|
Generates higher frequency |
 Price per pair* |
399USD
vs
999USD
|
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.
Polk Monitor XT12 needs about 23% more floor area. Polk Monitor XT12 stands 75mm further into the room.
| General |
KEF Kube 12 MIE |
Polk Monitor XT12 |
| Brand |
KEF |
Polk Audio |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
300 watts |
50 watts |
| Frequency Response |
22-140 Hz |
24-160 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
300-watt RMS |
50-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
12" |
12" |
| Woofer Composition |
Polypropylene |
Bi-laminate paper |
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
40-140 Hz |
n/a |
| Firing Direction |
n/a |
front |
Physical Specs |
|
|
| Height |
410.0mm (16.1") |
418.0mm (16.5") |
| Width |
393.0mm (15.5") |
408.0mm (16.1") |
| Depth |
410.0mm (16.1") |
485.0mm (19.1") |
| Weight |
18.60kg (40.9lbs) |
17.73kg (39lbs) |
| Enclosure |
Acoustic Suspension |
Bass Reflex |
| Grille |
n/a |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
2 Years |
3 Years |
| Labor Warranty |
2 Years |
3 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 | evenly matched | Effectively the same reach (22Hz vs 24Hz). |
| Amplifier power | A | KEF Kube 12 MIE has the bigger amplifier - 300W against 50W RMS, about 7.8dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | evenly matched | Near-identical radiating area (12" against 12"). |
| Enclosure | depends | KEF Kube 12 MIE is sealed - a sealed box rolls off gently and is usually the easier one to integrate in a small or awkward room; Polk Monitor XT12 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 KEF Kube 12 MIE 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 12 MIE is about 20% 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 | B | Polk Monitor XT12 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 | B | Polk Monitor XT12 costs less - $399 against $999, about 60% less. |
A KEF Kube 12 MIE B Polk Monitor XT12
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?
Neither runs away with it - they trade advantages. Let your room size and where the box can actually stand settle it. Films or music? If this is mainly a home cinema, Polk Monitor XT12 will hit harder for the money; if it is mainly for music in a normal-sized room, KEF Kube 12 MIE 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 $399 each, two Polk Monitor XT12 cost about $798 against $999 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.