In this review, we will be comparing Gravis V and Monitor XT12, two Powered Subwoofer speakers from Sonus faber 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 Sonus faber Gravis V 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 Sonus faber Gravis Vand Polk Monitor XT12 have a single woofer setup however the Sonus faber Gravis V's woofer is 12.5-inch whereas the Polk Monitor XT12 features a 12-inch woofer.
Frequency Response
Gravis V has a frequency range of 20-120 Hz whereas Monitor XT12 has a frequency range of 24-160 Hz. With a minimum frequency of 20Hz, the Gravis V 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 Sonus faber Gravis V 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 Sonus faber Gravis V's and Polk Monitor XT12's external dimensions. Sonus faber Gravis V has external dimensions of 455.0 x 448.0 x 448.0mm (17-15/16 x 17-5/8 x 17-5/8inch) 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 40mm narrower and 37mm shorter than Sonus faber Gravis V but it is also 37mm deeper.
Size, drawn to scale
Both speakers 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 surface and pushed back to the same wall, so the deeper one visibly sticks out further.
Near-identical footprints. Polk Monitor XT12 is 37mm deeper, so it stands that much further out from the wall. Sonus faber Gravis V is 37mm taller.
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 Sonus faber Gravis V is approximately 2007.0cm2 / 311.1inch2 and base area of the Polk Monitor XT12 is approximately 1978.8cm2 / 306.7inch2. The Gravis V requires 1% 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 Sonus faber Gravis V weighs 32.00kg / 70.4lbs and the Polk Monitor XT12 weighs 17.73kg / 39lbs. This makes the Gravis V 80% heavier than the Monitor XT12.
Here is a comparison of how Gravis V and Monitor XT12's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
 Woofer Size |
12.5 inches
vs
12 inches
|
Larger woofer |
| Low Frequency Response |
20 Hz
vs
24 Hz
|
Generates deeper bass |
 High Frequency Response |
160 Hz
vs
120 Hz
|
Generates higher frequency |
 Height |
418mm
vs
455mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1978cm2
vs
2007cm2
|
Takes less floor space |
 Price per pair* |
399USD
vs
5000USD
|
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.
Near-identical footprints. Polk Monitor XT12 stands 37mm further into the room. Sonus faber Gravis V is 37mm taller.
| General |
Sonus faber Gravis V |
Polk Monitor XT12 |
| Brand |
Sonus faber |
Polk Audio |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
850 watts |
50 watts |
| Frequency Response |
20-120 Hz |
24-160 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
850-watt RMS |
50-watt RMS |
| Watts Peak (Max) |
1200-watt RMS |
n/a |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
12.5" |
12" |
| Woofer Composition |
Honeycomb sandwich |
Bi-laminate paper |
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
Continuously adjustable |
n/a |
| Firing Direction |
n/a |
front |
Physical Specs |
|
|
| Height |
455.0mm (17.9") |
418.0mm (16.5") |
| Width |
448.0mm (17.6") |
408.0mm (16.1") |
| Depth |
448.0mm (17.6") |
485.0mm (19.1") |
| Weight |
32.00kg (70.4lbs) |
17.73kg (39lbs) |
| Enclosure |
Acoustic Suspension |
Bass Reflex |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
|
3 Years |
| Labor Warranty |
|
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 | Sonus faber Gravis V goes deeper - 20Hz 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 | Sonus faber Gravis V has the bigger amplifier - 850W against 50W RMS, about 12.3dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | evenly matched | Near-identical radiating area (12.5" against 12"). |
| Enclosure | depends | Sonus faber Gravis V 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. |
| Price | B | Polk Monitor XT12 costs less - $399 against $5,000, about 92% less. |
A Sonus faber Gravis V 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: Sonus faber Gravis V measures better, Polk Monitor XT12 costs about 92% 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, Sonus faber Gravis V 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 $5,000 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.