In this review, we will be comparing Grotto 15 and SW-15, two Powered Subwoofer speakers from MartinLogan and Wharfedale. 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 Wharfedale SW-15 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 15and Wharfedale SW-15 have the same driver set up: Both subwoofers have 1 x 15" drivers.
Frequency Response
Grotto 15 has a frequency range of 20-120 Hz whereas SW-15 has a frequency range of 30-120 Hz. With a minimum frequency of 20Hz, the Grotto 15 can go significantly deeper on the low side and provide stronger bass compared to the SW-15's min frequency of 30Hz.
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 Wharfedale SW-15 have Bass Reflex type enclosure. Bass Reflex type subwoofers (aka Ported, Vented or Reflex Port) have enclosures that uses a port, hole or vent cut into the cabinet. Ported designs are generally more efficient than the 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 Wharfedale SW-15'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 Wharfedale SW-15 has external dimensions of 570.0 x 493.0 x 615.0mm (22-7/16inch x 19-3/8inch x 24-3/16inch).
MartinLogan Grotto 15 is 48mm shorter and 61mm less deeper than Wharfedale SW-15 but it is also 61mm wider.
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.
Near-identical footprints. Wharfedale SW-15 is 61mm deeper, so it stands that much further out from the wall. Wharfedale SW-15 is 48mm 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 Wharfedale SW-15 is approximately 3032.0cm2 / 470.0inch2. The Grotto 15 requires 1% more surface area than the SW-15 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 Wharfedale SW-15 weighs 31.57kg / 69.5lbs. This makes the Grotto 15 69% heavier than the SW-15.
Here is a comparison of how Grotto 15 and SW-15's weights compare with the average, max and min weights in Powered Subwoofer class.
Weight
All Subwoofer Speakers
 Low Frequency Response |
20 Hz
vs
30 Hz
|
Generates deeper bass |
 Passive Radiator |
2 x 15-inch
vs
None
|
Increases the bass performance |
 Height |
522mm
vs
570mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
3032cm2
vs
3069cm2
|
Takes less floor space |
 Price per pair* |
1199USD
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.
Near-identical footprints. Wharfedale SW-15 stands 61mm further into the room. Wharfedale SW-15 is 48mm taller.
| General |
MartinLogan Grotto 15 |
Wharfedale SW-15 |
| Brand |
MartinLogan |
Wharfedale |
| Speaker Type |
Powered Subwoofer |
Powered Subwoofer |
| Max Amplifier Output |
1000 watts |
400 watts |
| Frequency Response |
20-120 Hz |
30-120 Hz |
Amplifier |
|
|
| Watts RMS (Continuous) |
1000-watt RMS |
400-watt RMS |
| Watts Peak (Max) |
2000-watt RMS |
n/a |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
15" |
15" |
| Woofer Composition |
Aluminium |
Paper |
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
35–120Hz |
n/a |
| Firing Direction |
n/a |
front |
Physical Specs |
|
|
| Height |
522.0mm (20.6") |
570.0mm (22.4") |
| Width |
554.0mm (21.8") |
493.0mm (19.4") |
| Depth |
554.0mm (21.8") |
615.0mm (24.2") |
| Weight |
53.50kg (117.7lbs) |
31.57kg (69.5lbs) |
| Enclosure |
Acoustic Suspension |
Bass Reflex |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
Other |
|
|
| Parts Warranty |
|
3 Years |
| Labor Warranty |
|
3 Years |
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 15 goes deeper - 20Hz against 30Hz. Under 20Hz is felt more than heard - the bottom of a pipe organ and the bottom of a film mix. |
| Amplifier power | A | MartinLogan Grotto 15 has the bigger amplifier - 1000W against 400W RMS, about 4dB more on tap. In a large room that is headroom before the DSP starts limiting. |
| Driver area | evenly matched | Near-identical radiating area (15" against 15"). |
| 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; Wharfedale SW-15 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 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. |
| Price | B | Wharfedale SW-15 costs less - $1,199 against $2,800, about 57% less. |
A MartinLogan Grotto 15 B Wharfedale SW-15
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, Wharfedale SW-15 costs about 57% 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, Wharfedale SW-15 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.