In this review, we will be comparing Grotto 12 and A120P, two Powered Subwoofer speakers from MartinLogan and JBL. 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 JBL Stage A120P 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 12and JBL Stage A120P have the same driver set up: Both subwoofers have 1 x 12" drivers.
Frequency Response
Grotto 12 has a frequency range of 22-120 Hz whereas A120P has a frequency range of 32-150 Hz. With a minimum frequency of 22Hz, the Grotto 12 can go significantly deeper on the low side and provide stronger bass compared to the A120P's min frequency of 32Hz.
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 12 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 JBL Stage A120P have Bass reflex type enclosure.
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 12's and JBL Stage A120P'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 JBL Stage A120P has external dimensions of 415.0 x 393.0 x 475.0mm (16-5/16 x 15-7/16 x 18-11/16inch).
JBL Stage A120P is 61mm narrower and 37mm shorter than MartinLogan Grotto 12 but it is also 21mm deeper.
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 12 needs about 10% more floor or shelf area. JBL Stage A120P is 21mm deeper, so it stands that much further out from the wall. MartinLogan Grotto 12 is 37mm 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 12 is approximately 2061.2cm2 / 319.5inch2 and base area of the JBL Stage A120P is approximately 1866.8cm2 / 289.4inch2. The Grotto 12 requires 10% more surface area than the A120P 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 JBL Stage A120P weighs 18.68kg / 41.1lbs. This makes the Grotto 12 100% heavier than the A120P.
Here is a comparison of how Grotto 12 and A120P's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
 Low Frequency Response |
22 Hz
vs
32 Hz
|
Generates deeper bass |
 Passive Radiator |
2 x 12-inch
vs
None
|
Increases the bass performance |
 High Frequency Response |
150 Hz
vs
120 Hz
|
Generates higher frequency |
 Height |
415mm
vs
452mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
1866cm2
vs
2061cm2
|
Takes less floor space |
 Price per pair* |
300USD
vs
2300USD
|
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 12 needs about 10% more floor area. JBL Stage A120P stands 21mm further into the room. MartinLogan Grotto 12 is 37mm taller.
| General |
MartinLogan Grotto 12 |
JBL Stage A120P |
| Brand |
MartinLogan |
JBL |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
1000 watts |
250 watts |
| Frequency Response |
22-120 Hz |
32-150 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
1000-watt RMS |
250-watt RMS |
| Watts Peak (Max) |
2000-watt RMS |
500-watt RMS |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
12" |
12" |
| Woofer Composition |
Aluminium |
Polycellulose |
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
35–120Hz |
n/a |
| Firing Direction |
n/a |
front |
Physical Specs |
|
|
| Height |
452.0mm (17.8") |
415.0mm (16.3") |
| Width |
454.0mm (17.9") |
393.0mm (15.5") |
| Depth |
454.0mm (17.9") |
475.0mm (18.7") |
| Weight |
37.40kg (82.3lbs) |
18.68kg (41.1lbs) |
| Enclosure |
Acoustic Suspension |
Bass reflex |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
|
1 Year |
| Labor Warranty |
|
1 Year |
A sealed subwoofer against a ported 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 | A | MartinLogan Grotto 12 goes deeper - 22Hz against 32Hz. That gap covers the lowest notes of a five-string bass and a concert bass drum. |
| Amplifier power | A | MartinLogan Grotto 12 has the bigger amplifier - 1000W against 250W RMS, about 6dB 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 12"). |
| Enclosure | depends | MartinLogan Grotto 12 is sealed - a sealed box rolls off gently and is usually the easier one to integrate in a small or awkward room; JBL Stage A120P is ported - a ported box gives more output low down for its size, at the cost of a steeper roll-off below tuning. 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 12 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. |
| Cabinet size | depends | JBL Stage A120P is about 17% 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 | JBL Stage A120P costs less - $300 against $2,300, about 87% less. |
A MartinLogan Grotto 12 B JBL Stage A120P
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 12 measures better, JBL Stage A120P costs about 87% less. In a normal room, placement will make a bigger difference than the gap between these two. Films or music? If this is mainly a home cinema, JBL Stage A120P will hit harder for the money; if it is mainly for music in a normal-sized room, MartinLogan Grotto 12 is usually the easier one to make sound right. Check your amplifier first: if it has no subwoofer or preamp output, MartinLogan Grotto 12 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.