In this review, we will be comparing Grotto 15 and SuperSub XXL, two Powered Subwoofer speakers from MartinLogan and GoldenEar. 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 GoldenEar SuperSub XXL 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.MartinLogan Grotto 15 and GoldenEar SuperSub XXL have a totally different setup: the MartinLogan Grotto 15 features 1 x 15-inch drivers whereas the SuperSub XXL features 2 x 12-inch drivers.
Frequency Response
Grotto 15 has a frequency range of 20-120 Hz whereas SuperSub XXL has a frequency range of 10-250 Hz. With a minimum frequency of 10Hz, the SuperSub XXL can go significantly deeper on the low side and provide stronger bass compared to the Grotto 15'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
The MartinLogan Grotto 15 has a Acoustic Suspension type cabinet. 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. On the other hand the GoldenEar SuperSub XXL have Passive Radiator type enclosure. Passive Radiator type subwoofers sports a non-powered cone that moves in response to the main woofer to move air out in order to generate stronger bass in a smaller body compared to ported or sealed 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 GoldenEar SuperSub XXL'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 GoldenEar SuperSub XXL has external dimensions of 447.0 x 485.0 x 434.0mm (17-9/16inch x 19-1/16inch x 17-1/16inch).
MartinLogan Grotto 15 is clearly the larger of the two speakers. Its body is 69mm wider, 75mm taller and 120mm deeper than GoldenEar SuperSub XXL.
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 46% more floor or shelf area. MartinLogan Grotto 15 is 120mm deeper, so it stands that much further out from the wall. MartinLogan Grotto 15 is 75mm 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 GoldenEar SuperSub XXL is approximately 2104.9cm2 / 326.3inch2. The Grotto 15 requires 46% more surface area than the SuperSub XXL 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 GoldenEar SuperSub XXL weighs 37.27kg / 82lbs. This makes the Grotto 15 44% heavier than the SuperSub XXL.
Here is a comparison of how Grotto 15 and SuperSub XXL'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 |
| Number of Woofers |
2
vs
1
|
More woofers |
| Low Frequency Response |
10 Hz
vs
20 Hz
|
Generates deeper bass |
 High Frequency Response |
250 Hz
vs
120 Hz
|
Generates higher frequency |
 Height |
447mm
vs
522mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
2104cm2
vs
3069cm2
|
Takes less floor space |
 Price per pair* |
2499USD
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 46% more floor area. MartinLogan Grotto 15 stands 120mm further into the room. MartinLogan Grotto 15 is 75mm taller.
| General |
MartinLogan Grotto 15 |
GoldenEar SuperSub XXL |
| Brand |
MartinLogan |
GoldenEar |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
1000 watts |
1600 watts |
| Frequency Response |
20-120 Hz |
10-250 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
1000-watt RMS |
1600-watt RMS |
| Watts Peak (Max) |
2000-watt RMS |
n/a |
Drivers |
|
|
| Woofer Quantity |
1 |
2 |
| Woofer Size |
15" |
12" |
| Woofer Composition |
Aluminium |
Fiber |
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
35–120Hz |
n/a |
| Firing Direction |
n/a |
side |
Physical Specs |
|
|
| Height |
522.0mm (20.6") |
447.0mm (17.6") |
| Width |
554.0mm (21.8") |
485.0mm (19.1") |
| Depth |
554.0mm (21.8") |
434.0mm (17.1") |
| Weight |
53.50kg (117.7lbs) |
37.27kg (82lbs) |
| Enclosure |
Acoustic Suspension |
Passive Radiator |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
|
3 Years |
| Labor Warranty |
|
3 Years |
A sealed subwoofer against a passive radiator one. That is the most consequential line on this page: it decides how the bass rolls off, how it behaves in a small room, and how much output you get for the size of the box.
| Area | Better | Why |
|---|
| Bass depth | B | GoldenEar SuperSub XXL goes deeper - 10Hz against 20Hz. Under 20Hz is felt more than heard - the bottom of a pipe organ and the bottom of a film mix. |
| Amplifier power | B | GoldenEar SuperSub XXL has the bigger amplifier - 1600W against 1000W RMS, about 2dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | B | GoldenEar SuperSub XXL moves more air: 2 x 12" against 15" is 1.28x the cone area, not the 1.13x the diameters suggest. More area means the same output with less excursion, and less distortion with it. |
| Enclosure | depends | MartinLogan Grotto 15 is sealed - a sealed box rolls off gently and is usually the easier one to integrate in a small or awkward room; GoldenEar SuperSub XXL is passive radiator - a passive radiator behaves like a port without the pipe noise, and suits a slim cabinet. Neither is better in the abstract; ported tends to suit films and sealed tends to suit music, and both generalisations have exceptions. |
| Speaker-level inputs | A | MartinLogan Grotto 15 takes a speaker-level connection as well as line level. That is what lets it work with an integrated amplifier or a vintage receiver that has no subwoofer output at all. |
| Phase control | A | MartinLogan Grotto 15 has a phase control. Without one, the only way to fix a cancellation at the crossover is to move the box. |
| Driver placement | depends | MartinLogan Grotto 15 fires front and GoldenEar SuperSub XXL fires side. A down-firing driver is more forgiving of a grille-less look and of a hard floor; a front-firing one is the safer choice on a thick carpet or a suspended timber floor. |
| Cabinet size | depends | GoldenEar SuperSub XXL is about 41% 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 | GoldenEar SuperSub XXL costs less - $2,499 against $2,800, about 11% less. |
A MartinLogan Grotto 15 B GoldenEar SuperSub XXL
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?
GoldenEar SuperSub XXL has the edge on paper, though not by much. The "depends" rows are more likely to decide this than the score is. Films or music? If this is mainly a home cinema, GoldenEar SuperSub XXL will hit harder for the money; if it is mainly for music in a normal-sized room, MartinLogan Grotto 15 is usually the easier one to make sound right. Check your amplifier first: if it has no subwoofer or preamp output, MartinLogan Grotto 15 is the only one of these two you can connect at all.
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.