In this review, we will be comparing Gravis V and KF92, 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 V and KEF KF92 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 V and KEF KF92 have a totally different setup: the Sonus faber Gravis V features 1 x 12.5-inch drivers whereas the KF92 features 2 x 9-inch drivers.
Frequency Response
Gravis V has a frequency range of 20-120 Hz whereas KF92 has a frequency range of 11-200 Hz. With a minimum frequency of 11Hz, the KF92 can go significantly deeper on the low side and provide stronger bass compared to the Gravis V's min frequency of 20Hz.
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 V and KEF KF92 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 V's and KEF KF92'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 KEF KF92 has external dimensions of 353.0 x 331.0 x 362.0mm (13-7/8 x 13 x 14-1/4inch).
Sonus faber Gravis V is clearly the larger of the two speakers. Its body is 117mm wider, 102mm taller and 86mm deeper than KEF KF92.
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.
Sonus faber Gravis V needs about 68% more floor or shelf area. Sonus faber Gravis V is 86mm deeper, so it stands that much further out from the wall. Sonus faber Gravis V is 102mm 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 KEF KF92 is approximately 1198.2cm2 / 185.7inch2. The Gravis V requires 68% more surface area than the KF92 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 KEF KF92 weighs 20.05kg / 44.1lbs. This makes the Gravis V 60% heavier than the KF92.
Here is a comparison of how Gravis V and KF92's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
 Woofer Size |
12.5 inches
vs
9 inches
|
Larger woofer |
| Number of Woofers |
2
vs
1
|
More woofers |
| Low Frequency Response |
11 Hz
vs
20 Hz
|
Generates deeper bass |
 High Frequency Response |
200 Hz
vs
120 Hz
|
Generates higher frequency |
 Height |
353mm
vs
455mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1198cm2
vs
2007cm2
|
Takes less floor space |
 Price per pair* |
2000USD
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.
Sonus faber Gravis V needs about 68% more floor area. Sonus faber Gravis V stands 86mm further into the room. Sonus faber Gravis V is 102mm taller.
| General |
Sonus faber Gravis V |
KEF KF92 |
| Brand |
Sonus faber |
KEF |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
850 watts |
1000 watts |
| Frequency Response |
20-120 Hz |
11-200 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
850-watt RMS |
1000-watt RMS |
| Watts Peak (Max) |
1200-watt RMS |
n/a |
Drivers |
|
|
| Woofer Quantity |
1 |
2 |
| Woofer Size |
12.5" |
9" |
| Woofer Composition |
Honeycomb sandwich |
Hybrid aluminum |
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
Continuously adjustable |
n/a |
Physical Specs |
|
|
| Height |
455.0mm (17.9") |
353.0mm (13.9") |
| Width |
448.0mm (17.6") |
331.0mm (13") |
| Depth |
448.0mm (17.6") |
362.0mm (14.3") |
| Weight |
32.00kg (70.4lbs) |
20.05kg (44.1lbs) |
| Enclosure |
Acoustic Suspension |
Acoustic Suspension |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
|
2 Years |
| Labor Warranty |
|
2 Years |
Different price classes - Sonus faber Gravis V costs roughly 2.5x what KEF KF92 does. Before paying it, read the note below about two smaller subwoofers.
| Area | Better | Why |
|---|
| Bass depth | B | KEF KF92 goes deeper - 11Hz against 20Hz. Under 20Hz is felt more than heard - the bottom of a pipe organ and the bottom of a film mix. |
| Amplifier power | evenly matched | Much the same amplifier (850W vs 1000W RMS) - under 1dB apart. |
| Driver area | evenly matched | Near-identical radiating area (12.5" against 2 x 9"). |
| Enclosure | evenly matched | Both are sealed designs, so they roll off in much the same way. |
| Cabinet size | depends | KEF KF92 is about 54% 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 | B | KEF KF92 costs less - $2,000 against $5,000, about 60% less. |
A Sonus faber Gravis V B KEF KF92
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 KF92 has the edge on paper, though not by much. The "depends" rows are more likely to decide this than the score is. 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 $2,000 each, two KEF KF92 cost about $4,000 against $5,000 for one of the other, which is worth a thought. If placement is the constraint - a corner, behind a sofa, under a desk - KEF KF92 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.