In this review, we will be comparing Grotto 12 and KC92, 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 Grotto 12 and KEF KC92 first before getting into our more detailed comparison.
In the following sections, we will get into details in order to better understand how the MartinLogan Grotto 12 and KEF KC92 compare and hopefully end up with enough arguments to decide which one of these subwoofers is the better choice for you.
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Drivers
The efficiency of a subwoofer is directly proportional to the total radiating are squared hence the woofer quantity and diameter.MartinLogan Grotto 12 and KEF KC92 have a totally different setup: the MartinLogan Grotto 12 features 1 x 12-inch drivers whereas the KC92 features 2 x 9-inch drivers.
Frequency Response
Grotto 12 has a frequency range of 22-120 Hz whereas KC92 has a frequency range of 11-200 Hz. With a minimum frequency of 11Hz, the KC92 can go significantly deeper on the low side and provide stronger bass compared to the Grotto 12's min frequency of 22Hz.
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 MartinLogan Grotto 12 and KEF KC92 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
Size of a speaker can sometimes become 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 Grotto 12's and KEF KC92's external dimensions. MartinLogan Grotto 12 has external dimensions of 452.0 x 454.0 x 454.0mm ( 17-13/16 x 17-7/8 x 17-7/8inch) whereas KEF KC92 has external dimensions of 352.5 x 330 x 360.5 mm ( 13.88 x 13.00 x 14.19 in) .
MartinLogan Grotto 12 is clearly the larger of the two speakers. Its body is 124mm wider, 100mm taller and 93mm deeper than KEF KC92.
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 Grotto 12 is approximately 2061.2cm2 / 319.5inch2 and base area of the KEF KC92 is approximately 1191.3cm2 / 184.7inch2. The Grotto 12 requires 73% more surface area than the KC92 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 Grotto 12 weighs 37.40kg / 82.3lbs and the KEF KC92 weighs 20.00kg / 44lbs. This makes the Grotto 12 87% heavier than the KC92.
Here is a comparison of how Grotto 12 and KC92'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 |
 Passive Radiator |
2 x 12-inch
vs
None
|
Increases the bass performance |
| Number of Woofers |
2
vs
1
|
More woofers |
| Low Frequency Response |
11 Hz
vs
22 Hz
|
Generates deeper bass |
 High Frequency Response |
200k Hz
vs
120k Hz
|
Generates higher frequency |
 Height |
352mm
vs
452mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1191cm2
vs
2061cm2
|
Takes less floor space |
 Price per pair* |
1999USD
vs
2300USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
MartinLogan Grotto 12 |
KEF KC92 |
| Brand |
MartinLogan |
KEF |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
1000 watts |
1000 watts |
| Frequency Response |
22-120 Hz |
11-200 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
1000-watt RMS |
1000-watt RMS |
| Watts Peak (Max) |
2000-watt RMS |
n/a |
Drivers |
|
|
| Woofer Quantity |
1 |
2 |
| Woofer Size |
12" |
9" |
| Woofer Composition |
Aluminium |
Polypropylene |
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
35–120Hz |
40-140 Hz |
Physical Specs |
|
|
| Height |
452.0mm (17.8") |
352.0mm (13.9") |
| Width |
454.0mm (17.9") |
330.0mm (13") |
| Depth |
454.0mm (17.9") |
361.0mm (14.2") |
| Weight |
37.40kg (82.3lbs) |
20.00kg (44lbs) |
| Enclosure |
Acoustic Suspension |
Acoustic Suspension |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
|
2 Years |
| Labor Warranty |
|
2 Years |