In this review, we will be comparing Grotto 15 and Grotto 12, two Powered Subwoofer speakers by MartinLogan. 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 15 and MartinLogan Grotto 12 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 Grotto 15and MartinLogan Grotto 12 have a single woofer setup however the MartinLogan Grotto 15's woofer is 15-inch whereas the MartinLogan Grotto 12 features a 12-inch woofer.
Frequency Response
Grotto 15 has a frequency range of 20-120 Hz whereas Grotto 12 has a frequency range of 22-120 Hz. With a minimum frequency of 20Hz, the Grotto 15 can go slightly deeper then 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 15 and MartinLogan Grotto 12 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 Grotto 15's and MartinLogan Grotto 12's external dimensions. MartinLogan Grotto 15 has external dimensions of 522.0 x 554.0 x 554.0mm (20-9/16 x 21-13/16 x 21-13/16inch) whereas 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).
MartinLogan Grotto 15 is clearly the larger of the two speakers. Its body is 100mm wider, 70mm taller and 100mm deeper than MartinLogan Grotto 12.
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.
MartinLogan Grotto 15 needs about 49% more floor or shelf area. MartinLogan Grotto 15 is 100mm deeper, so it stands that much further out from the wall. MartinLogan Grotto 15 is 70mm 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 MartinLogan Grotto 15 is approximately 3069.2cm2 / 475.7inch2 and base area of the MartinLogan Grotto 12 is approximately 2061.2cm2 / 319.5inch2. The Grotto 15 requires 49% more surface area than the Grotto 12 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 15 weighs 53.50kg / 117.7lbs and the MartinLogan Grotto 12 weighs 37.40kg / 82.3lbs. This makes the Grotto 15 43% heavier than the Grotto 12.
Here is a comparison of how Grotto 15 and Grotto 12's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
 Woofer Size |
15 inches
vs
12 inches
|
Larger woofer |
| Low Frequency Response |
20 Hz
vs
22 Hz
|
Generates deeper bass |
 Height |
452mm
vs
522mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
2061cm2
vs
3069cm2
|
Takes less floor space |
 Price per pair* |
2300USD
vs
2800USD
|
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 Grotto 15 needs about 49% more floor area. MartinLogan Grotto 15 stands 100mm further into the room. MartinLogan Grotto 15 is 70mm taller.
| General |
MartinLogan Grotto 15 |
MartinLogan Grotto 12 |
| Brand |
MartinLogan |
MartinLogan |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
1000 watts |
1000 watts |
| Frequency Response |
20-120 Hz |
22-120 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
1000-watt RMS |
1000-watt RMS |
| Watts Peak (Max) |
2000-watt RMS |
2000-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
15" |
12" |
| Woofer Composition |
Aluminium |
Aluminium |
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
35–120Hz |
35–120Hz |
Physical Specs |
|
|
| Height |
522.0mm (20.6") |
452.0mm (17.8") |
| Width |
554.0mm (21.8") |
454.0mm (17.9") |
| Depth |
554.0mm (21.8") |
454.0mm (17.9") |
| Weight |
53.50kg (117.7lbs) |
37.40kg (82.3lbs) |
| Enclosure |
Acoustic Suspension |
Acoustic Suspension |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
|
|
| Labor Warranty |
|
|
Siblings in MartinLogan's Grotto range - same design thinking, different size. It comes down to your room and your budget.
| Area | Better | Why |
|---|
| Bass depth | evenly matched | Effectively the same reach (20Hz vs 22Hz). |
| Amplifier power | evenly matched | Much the same amplifier (1000W vs 1000W RMS) - under 1dB apart. |
| Driver area | A | MartinLogan Grotto 15 moves more air: 15" against 12" is 1.56x the cone area, not the 1.25x 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 | MartinLogan Grotto 12 is about 42% 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 | MartinLogan Grotto 12 costs less - $2,300 against $2,800, about 18% less. |
A MartinLogan Grotto 15 B MartinLogan Grotto 12
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: MartinLogan Grotto 15 measures better, MartinLogan Grotto 12 costs about 18% 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 - MartinLogan Grotto 12 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.