In this review, we will be comparing KC92 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 KC92 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 KC92 and Polk Monitor XT12 have a totally different setup: the KEF KC92 features 2 x 9-inch drivers whereas the Monitor XT12 features 1 x 12-inch drivers.
Frequency Response
KC92 has a frequency range of 11-200 Hz whereas Monitor XT12 has a frequency range of 24-160 Hz. With a minimum frequency of 11Hz, the KC92 can go significantly deeper on the low side and provide stronger bass compared to 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 KC92 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 KC92's and Polk Monitor XT12's external dimensions. KEF KC92 has external dimensions of 352.5 x 330 x 360.5 mm (13.88 x 13.00 x 14.19 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 78mm wider, 66mm taller and 124mm deeper than KEF KC92.
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 KC92 is approximately 1191.3cm2 / 184.7inch2 and base area of the Polk Monitor XT12 is approximately 1978.8cm2 / 306.7inch2. The KC92 requires 40% 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 KC92 weighs 20.00kg / 44lbs and the Polk Monitor XT12 weighs 17.73kg / 39lbs. This makes the KC92 13% heavier than the Monitor XT12.
Here is a comparison of how KC92 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 KC92?
Here are the items that are included inside the box of KC92:
- KC92 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
 Number of Woofers |
2
vs
1
|
More woofers |
| Low Frequency Response |
11 Hz
vs
24 Hz
|
Generates deeper bass |
 High Frequency Response |
200 Hz
vs
160 Hz
|
Generates higher frequency |
 Height |
352mm
vs
418mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1191cm2
vs
1978cm2
|
Takes less floor space |
 Wireless Operation |
Optional
vs
No
|
Connect your subwoofer to your system wireless |
| Woofer Size |
12 inches
vs
9 inches
|
Larger woofer |
 Price per pair* |
399USD
vs
1999USD
|
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 66% more floor area. Polk Monitor XT12 stands 124mm further into the room. Polk Monitor XT12 is 66mm taller.
| General |
KEF KC92 |
Polk Monitor XT12 |
| Brand |
KEF |
Polk Audio |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
1000 watts |
50 watts |
| Frequency Response |
11-200 Hz |
24-160 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
1000-watt RMS |
50-watt RMS |
Drivers |
|
|
| Woofer Quantity |
2 |
1 |
| Woofer Size |
9" |
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 |
352.0mm (13.9") |
418.0mm (16.5") |
| Width |
330.0mm (13") |
408.0mm (16.1") |
| Depth |
361.0mm (14.2") |
485.0mm (19.1") |
| Weight |
20.00kg (44lbs) |
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 | A | KEF KC92 goes deeper - 11Hz against 24Hz. Under 20Hz is felt more than heard - the bottom of a pipe organ and the bottom of a film mix. |
| Amplifier power | A | KEF KC92 has the bigger amplifier - 1000W against 50W RMS, about 13dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | evenly matched | Near-identical radiating area (2 x 9" against 12"). |
| Enclosure | depends | KEF KC92 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 KC92 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 KC92 is about 49% 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 $1,999, about 80% less. |
A KEF KC92 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?
KEF KC92 is ahead, but on only 1 of the measured areas, and it costs about 5x the price. Polk Monitor XT12 is the sensible buy unless your room is large enough to need the extra. 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 KC92 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 $1,999 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.