In this review, we will be comparing Monitor XT12 and SUB8, two Powered Subwoofer speakers from Polk Audio and Kanto. 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 Polk Monitor XT12 and Kanto SUB8 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 Polk Monitor XT12and Kanto SUB8 have a single woofer setup however the Polk Monitor XT12's woofer is 12-inch whereas the Kanto SUB8 features a 8-inch woofer.
Frequency Response
Monitor XT12 has a frequency range of 24-160 Hz whereas SUB8 has a frequency range of 35-175 Hz. With a minimum frequency of 24Hz, the Monitor XT12 can go significantly deeper on the low side and provide stronger bass compared to the SUB8's min frequency of 35Hz.
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 Polk Monitor XT12 has a Bass Reflex type cabinet. 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. On the other hand the Kanto SUB8 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 Polk Monitor XT12's and Kanto SUB8's external dimensions. 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) whereas Kanto SUB8 has external dimensions of 301.0 x 281.0 x 329.0mm (11-13/16 x 11-1/16 x 12-15/16inch).
Polk Monitor XT12 is clearly the larger of the two speakers. Its body is 127mm wider, 117mm taller and 156mm deeper than Kanto SUB8.
Below you can see the front view size comparison of Polk Monitor XT12 and Kanto SUB8 in scale.
Comparison image of Polk Monitor XT12 and Kanto SUB8 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 Polk Monitor XT12 is approximately 1978.8cm2 / 306.7inch2 and base area of the Kanto SUB8 is approximately 924.5cm2 / 143.3inch2. The Monitor XT12 requires 114% more surface area than the SUB8 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 Polk Monitor XT12 weighs 17.73kg / 39lbs and the Kanto SUB8 weighs 7.82kg / 17.2lbs. This makes the Monitor XT12 127% heavier than the SUB8.
Here is a comparison of how Monitor XT12 and SUB8's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
What's in the Box of Polk Monitor XT12?
Here are the items that are included inside the box of Monitor XT12:
- Black powered subwoofer
- 6.5-feet AC power cord
- Grille
- Owners Manual
- Online registration card
What's in the Box of Kanto SUB8?
Here are the items that come with the SUB8:
- Powered subwoofer
- 6-feet AC power cord
- 9.75-feet mono-RCA cable
- User Manual
 Woofer Size |
12 inches
vs
8 inches
|
Larger woofer |
| Low Frequency Response |
24 Hz
vs
35 Hz
|
Generates deeper bass |
 High Frequency Response |
175 Hz
vs
160 Hz
|
Generates higher frequency |
 Height |
301mm
vs
418mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
924cm2
vs
1978cm2
|
Takes less floor space |
 Price per pair* |
300USD
vs
399USD
|
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 114% more floor area. Polk Monitor XT12 stands 156mm further into the room. Polk Monitor XT12 is 117mm taller.
| General |
Polk Monitor XT12 |
Kanto SUB8 |
| Brand |
Polk Audio |
Kanto |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
50 watts |
125 watts |
| Frequency Response |
24-160 Hz |
35-175 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
50-watt RMS |
125-watt RMS |
| Watts Peak (Max) |
n/a |
250-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
12" |
8" |
| Woofer Composition |
Bi-laminate paper |
Paper |
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Firing Direction |
front |
front |
Physical Specs |
|
|
| Height |
418.0mm (16.5") |
301.0mm (11.9") |
| Width |
408.0mm (16.1") |
281.0mm (11.1") |
| Depth |
485.0mm (19.1") |
329.0mm (13") |
| Weight |
17.73kg (39lbs) |
7.82kg (17.2lbs) |
| Enclosure |
Bass Reflex |
Acoustic Suspension |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
3 Years |
2 Years |
| Labor Warranty |
3 Years |
2 Years |
A ported subwoofer against a sealed 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 | Polk Monitor XT12 goes deeper - 24Hz against 35Hz. That gap covers the lowest notes of a five-string bass and a concert bass drum. |
| Amplifier power | B | Kanto SUB8 has the bigger amplifier - 125W against 50W RMS, about 4dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | A | Polk Monitor XT12 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 | 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; Kanto SUB8 is sealed - a sealed box rolls off gently and is usually the easier one to integrate in a small or awkward room. Neither is better in the abstract; ported tends to suit films and sealed tends to suit music, and both generalisations have exceptions. |
| Speaker-level inputs | A | Polk Monitor XT12 takes a speaker-level connection as well as line level. That is what lets it work with an integrated amplifier or a vintage receiver that has no subwoofer output at all. |
| Cabinet size | depends | Kanto SUB8 is about 66% 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 | 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 | Kanto SUB8 costs less - $300 against $399, about 25% less. |
A Polk Monitor XT12 B Kanto SUB8
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?
Polk Monitor XT12 leads across most of the measured areas for a modest premium, so it is the easier pick if the budget stretches. Kanto SUB8 is the one to take if it does not. 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, Kanto SUB8 is usually the easier one to make sound right. Check your amplifier first: if it has no subwoofer or preamp output, Polk Monitor XT12 is the only one of these two you can connect at all.
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.