In this review, we will be comparing Gravis I and KC62, two Powered Subwoofer speakers from Sonus faber and KEF. 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 I and KEF KC62 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.Sonus faber Gravis I and KEF KC62 have a totally different setup: the Sonus faber Gravis I features 1 x 8-inch drivers whereas the KC62 features 2 x 6.5-inch drivers.
Frequency Response
Gravis I has a frequency range of 30-120 Hz whereas KC62 has a frequency range of 11-200 Hz. With a minimum frequency of 11Hz, the KC62 can go significantly deeper on the low side and provide stronger bass compared to the Gravis I's min frequency of 30Hz.
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
Both Sonus faber Gravis I and KEF KC62 have Acoustic Suspension type cabinets. 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 Sonus faber Gravis I's and KEF KC62's external dimensions. Sonus faber Gravis I has external dimensions of 337.0 x 286.0 x 340.0mm (13-1/4inch x 11-1/4inch x 13-3/8inch) whereas KEF KC62 has external dimensions of 245.0 x 258.0 x 281.0mm (9-5/8inch x 10-1/8inch x 11-1/16inch).
Sonus faber Gravis I is clearly the larger of the two speakers. Its body is 28mm wider, 92mm taller and 59mm deeper than KEF KC62.
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 I is approximately 972.4cm2 / 150.7inch2 and base area of the KEF KC62 is approximately 725.0cm2 / 112.4inch2. The Gravis I requires 34% more surface area than the KC62 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 I weighs 14.55kg / 32lbs and the KEF KC62 weighs 14.05kg / 30.9lbs. This makes the Gravis I 4% heavier than the KC62.
Here is a comparison of how Gravis I and KC62's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
What's in the Box of Sonus faber Gravis I?
Here are the items that are included inside the box of Gravis I:
- Powered subwoofer
- 6-feet AC power cord
- 33-feet Speakon cable
- Owners Manual
- Environmental Information
What's in the Box of KEF KC62?
Here are the items that come with the KC62:
- Powered subwoofer
- 6.5-feet AC power cord
- Speaker-level input block
- User Manual
- Important Safety Information
- Warranty Information
 Woofer Size |
8 inches
vs
6.5 inches
|
Larger woofer |
 Price per pair* |
999USD
vs
1500USD
|
costs less (*prices may change depending on the seller, location and time) |
| Number of Woofers |
2
vs
1
|
More woofers |
| Low Frequency Response |
11 Hz
vs
30 Hz
|
Generates deeper bass |
 High Frequency Response |
200 Hz
vs
120 Hz
|
Generates higher frequency |
 Height |
245mm
vs
337mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
725cm2
vs
972cm2
|
Takes less floor space |
 Wireless Operation |
Optional
vs
No
|
Connect your subwoofer to your system wireless |
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.
Sonus faber Gravis I needs about 34% more floor area. Sonus faber Gravis I stands 59mm further into the room. Sonus faber Gravis I is 92mm taller.
| General |
Sonus faber Gravis I |
KEF KC62 |
| Brand |
Sonus faber |
KEF |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
150 watts |
1000 watts |
| Frequency Response |
30-120 Hz |
11-200 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
150-watt RMS |
1000-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
2 |
| Woofer Size |
8" |
6.5" |
| Woofer Composition |
Treated Paper |
|
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Firing Direction |
bottom |
side |
Physical Specs |
|
|
| Height |
337.0mm (13.3") |
245.0mm (9.6") |
| Width |
286.0mm (11.3") |
258.0mm (10.2") |
| Depth |
340.0mm (13.4") |
281.0mm (11.1") |
| Weight |
14.55kg (32lbs) |
14.05kg (30.9lbs) |
| Enclosure |
Acoustic Suspension |
Acoustic Suspension |
| Available Colors |
Piano Black,Matte White |
n/a |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
2 Yr/3 Yr registered |
2 Years |
| Labor Warranty |
2 Yr/3 Yr registered |
2 Years |
No single best subwoofer here. Your room, where the box can physically go, and whether this is mainly for films or mainly for music will settle it long before the specs do.
| Area | Better | Why |
|---|
| Bass depth | B | KEF KC62 goes deeper - 11Hz against 30Hz. Under 20Hz is felt more than heard - the bottom of a pipe organ and the bottom of a film mix. |
| Amplifier power | B | KEF KC62 has the bigger amplifier - 1000W against 150W RMS, about 8.2dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | B | KEF KC62 moves more air: 2 x 6.5" against 8" is 1.32x the cone area, not the 1.15x the diameters suggest. More area means the same output with less excursion, and less distortion with it. |
| Enclosure | evenly matched | Both are sealed designs, so they roll off in much the same way. |
| Wireless option | depends | Only KEF KC62 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. |
| Driver placement | depends | Sonus faber Gravis I fires down and KEF KC62 fires side. A down-firing driver is more forgiving of a grille-less look and of a hard floor; a front-firing one is the safer choice on a thick carpet or a suspended timber floor. |
| Cabinet size | depends | KEF KC62 is about 46% 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. |
| Price | A | Sonus faber Gravis I costs less - $999 against $1,500, about 33% less. |
A Sonus faber Gravis I B KEF KC62
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: KEF KC62 measures better, Sonus faber Gravis I costs about 33% less. In a normal room, placement will make a bigger difference than the gap between these two. If placement is the constraint - a corner, behind a sofa, under a desk - KEF KC62 is the one that will actually go there, and a well-placed small subwoofer beats a badly-placed big one every time.
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.