In this review, we will be comparing Dynamo IW S and IW Sub Reference, two Passive In-wall speakers from MartinLogan and Definitive Technology. Let's have a brief look at the main features of MartinLogan Dynamo IW S and Definitive IW Sub Reference 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 Dynamo IW S and Definitive IW Sub Reference have a totally different setup: the MartinLogan Dynamo IW S features 2 x 8-inch drivers whereas the IW Sub Reference features 1 x 13-inch drivers.
Frequency Response
Dynamo IW S has a frequency range of 35-190 Hz whereas IW Sub Reference has a frequency range of 14-200Hz. With a minimum frequency of 14Hz, the IW Sub Reference can go significantly deeper on the low side and provide stronger bass compared to the Dynamo IW S's min frequency of 35Hz.
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 In-wall class in our database.
Low Frequency
In-wall Speakers
Definitive IW Sub Reference
High Frequency
In-wall Speakers
Definitive IW Sub Reference
Input Type and Bi-Amping / Bi-Wiring
Dynamo IW S features Spring post type posts and IW Sub Reference has a Spring post type posts. None of these speakers feature bi-amping/bi-wiring.
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 Dynamo IW S's and Definitive IW Sub Reference's external dimensions. MartinLogan Dynamo IW S has external dimensions of 490.5 x 277.8 x 114.3mm () whereas Definitive IW Sub Reference has external dimensions of 639.0 x 366.0 x 102.0mm (25.1250-inch x 14.3750-inch x 4.0000-inch).
MartinLogan Dynamo IW S is 88.2mm narrower and 148.5mm shorter than Definitive IW Sub Reference but it is also 12.3mm deeper.
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 Dynamo IW S weighs 12.11kg / 26.6lbs and the Definitive IW Sub Reference weighs 11.79kg / 25.9lbs. This makes the Dynamo IW S 3% heavier than the IW Sub Reference.
Here is a comparison of how Dynamo IW S and IW Sub Reference's weights compare with the average, max and min weights in Passive In-wall class.
Weight
All In-wall Speakers
Definitive IW Sub Reference
 Nominal Impedance |
8 ohms
vs
4 ohms
|
Less selective with amplifiers |
 Number of Woofers |
2
vs
1
|
More woofers |
 Height |
490mm
vs
639mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
317cm2
vs
373cm2
|
Takes less floor space |
| Woofer Size |
13 inches
vs
8 inches
|
Larger woofer |
| Low Frequency Response |
14 Hz
vs
35 Hz
|
Generates deeper bass |
 High Frequency Response |
200 Hz
vs
190 Hz
|
Generates higher frequency |
 Passive Radiator |
1 x 13-inch
vs
None
|
Increases the bass performance |
 Price per pair* |
1499USD
vs
1600USD
|
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.
Definitive IW Sub Reference needs about 18% more floor area. Definitive IW Sub Reference is 149mm taller.
| General |
MartinLogan Dynamo IW S |
Definitive Technology IW Sub Reference |
| Brand |
MartinLogan |
Definitive Technology |
| Speaker Type |
Passive Subwoofer |
Passive Subwoofer |
| Impedance |
8 ohms |
4 ohms |
| Frequency Response |
35-190 Hz |
14-200Hz |
Drivers |
|
|
| Woofer Quantity |
2 |
1 |
| Woofer Size |
8" |
13" |
| Woofer Composition |
|
|
| Tweeter Size |
- |
- |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
Physical Specs |
|
|
| Height |
490.5mm (19.3") |
639.0mm (25.2") |
| Width |
277.8mm (10.9") |
366.0mm (14.4") |
| Depth |
114.3mm (4.5") |
102.0mm (4") |
| Weight |
12.11kg (26.6lbs) |
11.79kg (25.9lbs) |
| Enclosure |
|
In-wall |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
n/a |
No |
Other |
|
|
| Parts Warranty |
5 Years |
5 Years |
| Labor Warranty |
5 Years |
5 Years |
No single best subwoofer here. Your room, where the box can physically go, and whether this is mainly for films or mainly for music will settle it long before the specs do.
| Area | Better | Why |
|---|
| Bass depth | B | Definitive IW Sub Reference goes deeper - 14Hz against 35Hz. Under 20Hz is felt more than heard - the bottom of a pipe organ and the bottom of a film mix. |
| Driver area | B | Definitive IW Sub Reference moves more air: 13" against 2 x 8" is 1.32x the cone area, not the 1.15x the diameters suggest. More area means the same output with less excursion, and less distortion with it. |
| Cabinet size | depends | MartinLogan Dynamo IW S is about 35% 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 | Definitive IW Sub Reference costs less - $1,499 against $1,600, about 6% less. |
A MartinLogan Dynamo IW S B Definitive IW Sub Reference
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?
Definitive IW Sub Reference has the edge on paper, though not by much. The "depends" rows are more likely to decide this than the score is. If placement is the constraint - a corner, behind a sofa, under a desk - MartinLogan Dynamo IW S 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.