In this review, we will be comparing BalancedForce 210 and KF92, two Powered Subwoofer speakers from MartinLogan 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 MartinLogan BalancedForce 210 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.Both MartinLogan BalancedForce 210and KEF KF92 have a double woofer setup however the MartinLogan BalancedForce 210's woofer is 10-inch whereas the KEF KF92 features a 9-inch woofer.
Frequency Response
BalancedForce 210 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 BalancedForce 210'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
MartinLogan BalancedForce 210
High Frequency
Subwoofer Speakers
MartinLogan BalancedForce 210
Cabinet Type
Both MartinLogan BalancedForce 210 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 MartinLogan BalancedForce 210's and KEF KF92's external dimensions. MartinLogan BalancedForce 210 has external dimensions of 485.0 x 486.0 x 543.0mm (19-1/16inch x 19-1/8inch x 21-3/8inch) whereas KEF KF92 has external dimensions of 353.0 x 331.0 x 362.0mm (13-7/8 x 13 x 14-1/4inch).
MartinLogan BalancedForce 210 is clearly the larger of the two speakers. Its body is 155mm wider, 132mm taller and 181mm 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 MartinLogan BalancedForce 210 is approximately 2639.0cm2 / 409.0inch2 and base area of the KEF KF92 is approximately 1198.2cm2 / 185.7inch2. The BalancedForce 210 requires 120% 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 MartinLogan BalancedForce 210 weighs 43.64kg / 96lbs and the KEF KF92 weighs 20.05kg / 44.1lbs. This makes the BalancedForce 210 118% heavier than the KF92.
Here is a comparison of how BalancedForce 210 and KF92's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
MartinLogan BalancedForce 210
What's in the Box of MartinLogan BalancedForce 210?
Here are the items that are included inside the box of BalancedForce 210:
- Powered subwoofer
- Top-glass cover
- 2 Grilles
- 8-feet AC power cord
- 4 Spike feet
- 4 Collars
- USB thumbdrive
- User-feets Manual
- Online Registration Card
What's in the Box of KEF KF92?
Here are the items that come with the KF92:
- Powered subwoofer
- 6.5-feet AC power cord
- Speaker-level input block
- User Manual
- Important Safety Information
- Warranty Information
 Woofer Size |
10 inches
vs
9 inches
|
Larger woofer |
| 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
485mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1198cm2
vs
2639cm2
|
Takes less floor space |
 Price per pair* |
2000USD
vs
3499USD
|
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.
MartinLogan BalancedForce 210 needs about 120% more floor area. MartinLogan BalancedForce 210 stands 181mm further into the room. MartinLogan BalancedForce 210 is 132mm taller.
| General |
MartinLogan BalancedForce 210 |
KEF KF92 |
| Brand |
MartinLogan |
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) |
1700-watt RMS |
n/a |
Drivers |
|
|
| Woofer Quantity |
2 |
2 |
| Woofer Size |
10" |
9" |
| Woofer Composition |
Aluminum |
Hybrid aluminum |
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Firing Direction |
front |
n/a |
Physical Specs |
|
|
| Height |
485.0mm (19.1") |
353.0mm (13.9") |
| Width |
486.0mm (19.1") |
331.0mm (13") |
| Depth |
543.0mm (21.4") |
362.0mm (14.3") |
| Weight |
43.64kg (96lbs) |
20.05kg (44.1lbs) |
| Enclosure |
Acoustic Suspension |
Acoustic Suspension |
| Available Colors |
Gloss Black, Black Ash |
n/a |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
3 Years w/ Registration |
2 Years |
| Labor Warranty |
3 Years w/ Registration |
2 Years |
Different price classes - MartinLogan BalancedForce 210 costs roughly 1.7x 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 | A | MartinLogan BalancedForce 210 moves more air: 2 x 10" against 2 x 9" is 1.23x the cone area, not the 1.11x 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. |
| Cabinet size | depends | KEF KF92 is about 67% 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 | MartinLogan BalancedForce 210 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 | B | KEF KF92 costs less - $2,000 against $3,499, about 43% less. |
A MartinLogan BalancedForce 210 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?
MartinLogan BalancedForce 210 is ahead, but on only 1 of the measured areas, and it costs about 75% more. KEF KF92 is the sensible buy unless your room is large enough to need the extra. 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 $3,499 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.