In this review, we will be comparing SB17 Ultra R Evolution and Monitor XT12, two Powered Subwoofer speakers from SVS 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 SVS SB17 Ultra R Evolution 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.Both SVS SB17 Ultra R Evolutionand Polk Monitor XT12 have a single woofer setup however the SVS SB17 Ultra R Evolution's woofer is 17-inch whereas the Polk Monitor XT12 features a 12-inch woofer.
Frequency Response
SB17 Ultra R Evolution has a frequency range of 15-320 Hz whereas Monitor XT12 has a frequency range of 24-160 Hz. With a minimum frequency of 15Hz, the SB17 Ultra R Evolution 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
SVS SB17 Ultra R Evolution
High Frequency
Subwoofer Speakers
SVS SB17 Ultra R Evolution
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 SVS SB17 Ultra R Evolution's and Polk Monitor XT12's external dimensions. SVS SB17 Ultra R Evolution has external dimensions of 508.0 x 495.3 x 539.8mm () 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).
SVS SB17 Ultra R Evolution is clearly the larger of the two speakers. Its body is 87.3mm wider, 90mm taller and 54.8mm deeper than Polk Monitor XT12.
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 SVS SB17 Ultra R Evolution is approximately 2673.6cm2 / 414.4inch2 and base area of the Polk Monitor XT12 is approximately 1978.8cm2 / 306.7inch2. The SB17 Ultra R Evolution requires 35% more surface area than the Monitor XT12 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 SVS SB17 Ultra R Evolution weighs 56.25kg / 123.8lbs and the Polk Monitor XT12 weighs 17.73kg / 39lbs. This makes the SB17 Ultra R Evolution 217% heavier than the Monitor XT12.
Here is a comparison of how SB17 Ultra R Evolution and Monitor XT12's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
SVS SB17 Ultra R Evolution
 Woofer Size |
17 inches
vs
12 inches
|
Larger woofer |
| Low Frequency Response |
15 Hz
vs
24 Hz
|
Generates deeper bass |
 High Frequency Response |
320 Hz
vs
160 Hz
|
Generates higher frequency |
 Height |
418mm
vs
508mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1978cm2
vs
2673cm2
|
Takes less floor space |
 Price per pair* |
399USD
vs
2700USD
|
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.
SVS SB17 Ultra R Evolution needs about 35% more floor area. SVS SB17 Ultra R Evolution stands 55mm further into the room. SVS SB17 Ultra R Evolution is 90mm taller.
| General |
SVS SB17 Ultra R Evolution |
Polk Monitor XT12 |
| Brand |
SVS |
Polk Audio |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Frequency Response |
15-320 Hz |
24-160 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
2800-watt RMS |
50-watt RMS |
| Watts Peak (Max) |
6000-watt RMS |
n/a |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
17" |
12" |
| Woofer Composition |
|
Bi-laminate paper |
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Firing Direction |
n/a |
front |
Physical Specs |
|
|
| Height |
508.0mm (20") |
418.0mm (16.5") |
| Width |
495.3mm (19.5") |
408.0mm (16.1") |
| Depth |
539.8mm (21.3") |
485.0mm (19.1") |
| Weight |
56.25kg (123.8lbs) |
17.73kg (39lbs) |
| Enclosure |
|
Bass Reflex |
| Grille |
n/a |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
5 Years |
3 Years |
| Labor Warranty |
5 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 | SVS SB17 Ultra R Evolution goes deeper - 15Hz 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 | SVS SB17 Ultra R Evolution has the bigger amplifier - 2800W against 50W RMS, about 17.5dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | A | SVS SB17 Ultra R Evolution moves more air: 17" against 12" is 2.01x the cone area, not the 1.42x the diameters suggest. More area means the same output with less excursion, and less distortion with it. |
| Enclosure | depends | SVS SB17 Ultra R Evolution 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. |
| Cabinet size | depends | Polk Monitor XT12 is about 39% 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 | SVS SB17 Ultra R Evolution carries 5 years on parts against 3 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 $2,700, about 85% less. |
A SVS SB17 Ultra R Evolution 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?
The usual trade-off: SVS SB17 Ultra R Evolution measures better, Polk Monitor XT12 costs about 85% less. In a normal room, placement will make a bigger difference than the gap between these two. 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, SVS SB17 Ultra R Evolution 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 $2,700 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.