In this review, we will be comparing Classic 99 and KF92, two Powered Subwoofer speakers from REL 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 REL Classic 99 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.REL Classic 99 and KEF KF92 have a totally different setup: the REL Classic 99 features 1 x 12-inch drivers whereas the KF92 features 2 x 9-inch drivers.
Frequency Response
Classic 99 has a frequency range of 24-120 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 Classic 99'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
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 REL Classic 99's and KEF KF92's external dimensions. REL Classic 99 has external dimensions of 536.6 x 400.1 x 396.9mm () whereas KEF KF92 has external dimensions of 353.0 x 331.0 x 362.0mm (13-7/8 x 13 x 14-1/4inch).
REL Classic 99 is clearly the larger of the two speakers. Its body is 69.1mm wider, 183.6mm taller and 34.9mm deeper than KEF KF92.
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 REL Classic 99 is approximately 1588.0cm2 / 246.1inch2 and base area of the KEF KF92 is approximately 1198.2cm2 / 185.7inch2. The Classic 99 requires 33% 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 REL Classic 99 weighs 22.36kg / 49.2lbs and the KEF KF92 weighs 20.05kg / 44.1lbs. This makes the Classic 99 12% heavier than the KF92.
Here is a comparison of how Classic 99 and KF92's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
 Woofer Size |
12 inches
vs
9 inches
|
Larger woofer |
| Number of Woofers |
2
vs
1
|
More woofers |
| Low Frequency Response |
11 Hz
vs
24 Hz
|
Generates deeper bass |
 High Frequency Response |
200 Hz
vs
120 Hz
|
Generates higher frequency |
 Height |
353mm
vs
536mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1198cm2
vs
1588cm2
|
Takes less floor space |
 Price per pair* |
2000USD
vs
2099USD
|
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.
REL Classic 99 needs about 33% more floor area. REL Classic 99 stands 35mm further into the room. REL Classic 99 is 184mm taller.
| General |
REL Classic 99 |
KEF KF92 |
| Brand |
REL |
KEF |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Frequency Response |
24-120 Hz |
11-200 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
450-watt RMS |
1000-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
2 |
| Woofer Size |
12" |
9" |
| Woofer Composition |
|
Hybrid aluminum |
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
Physical Specs |
|
|
| Height |
536.6mm (21.1") |
353.0mm (13.9") |
| Width |
400.1mm (15.8") |
331.0mm (13") |
| Depth |
396.9mm (15.6") |
362.0mm (14.3") |
| Weight |
22.36kg (49.2lbs) |
20.05kg (44.1lbs) |
| Enclosure |
|
Acoustic Suspension |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
3 Years |
2 Years |
| Labor Warranty |
3 Years |
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 KF92 goes deeper - 11Hz against 24Hz. Under 20Hz is felt more than heard - the bottom of a pipe organ and the bottom of a film mix. |
| Amplifier power | B | KEF KF92 has the bigger amplifier - 1000W against 450W RMS, about 3.5dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | evenly matched | Near-identical radiating area (12" 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 50% 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 | REL Classic 99 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 | evenly matched | Priced within a few per cent of each other. |
A REL Classic 99 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. 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.