In this review, we will be comparing two different types of speakers by MartinLogan. MartinLogan Motion 15i is a Bookshelf speaker whereas the Motion 20i is a Floor-standing speaker.
Let's have a brief look at the main features
of MartinLogan 15i and MartinLogan 20i first before getting into our more
detailed comparison.
| Key Specs | MartinLogan 15i | MartinLogan 20i |
|---|
| Brand | MartinLogan
United States · founded 1982 | MartinLogan
United States · founded 1982 |
|---|
| Design | 2-way | 2-way |
|---|
| Tweeter | 1.0 x 1.4" Folded Motion | 1.0 x 1.4" Folded Motion |
|---|
| Woofer | 5.25" Aluminum | 2 x 5.5" Aluminum |
|---|
| Frequency response | 60-25k Hz | 46-25k Hz |
|---|
| Sensitivity | 92 dB | 90 dB |
|---|
| Impedance | 5 ohms | 4 ohms |
|---|
| Power range | 20-200 watts | 20-200 watts |
|---|
| Weight | 5.40kg / 11.9lbs | 15.00kg / 33lbs |
|---|
| Dimensions (H x W x D) | 11.4" x 6.8" x 9.4"
290.0 x 173.0 x 240.0mm | 35-5/8" x 6-7/8" x 12-1/16"
905.0 x 175.0 x 307.0mm |
|---|
Motion 15i and Motion 20i are members of MartinLogan's Motion series of speakers. Below you can find the loudspeakers from this series.
MartinLogan Motion Series
History
What size room are the MartinLogan 15i and MartinLogan 20i speakers good for?
The size of the room in which you are planning to use these loudspeakers is an important decision
factor. Here we have compared their suitability to various sizes of environments considering their size
and max power parameters:
| Listening Environment* |
MartinLogan 15i |
MartinLogan 20i |
| Near-field |
Poor |
Bad |
| Small Room |
Average |
Poor |
| Mid-size Room |
Good |
Good |
| Large Room |
Average |
Good |
| Very Large Room |
Poor |
Poor |
(* Approximate Room sizes: Small < 100sq. ft / 9 m2,
Mid-size: 100-220 sq. ft / 9-20 m2, Large 220-400 sq. ft / 20-36 m2, Very Large: >
400 sq. ft / 36 m2.
Average Floor Height: 9" / 2.7m. Typical room sizes differ from country to country, and the actual
listening experience changes depending on floor height, room shape, surface materials, listening
position, speaker locations, etc.)
The sections below take each area in turn: drivers, frequency response, physical size and what you get in the box.
Drivers
Both Motion 15i and Motion 20i are 2-way speakers.
MartinLogan 15iMartinLogan 20i
Woofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
MartinLogan 15i |
MartinLogan 20i |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1.0 x 1.4-inch
|
1.0 x 1.4-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5.25-inch
|
2 x 5.5-inch
|
Motion 15i features a 1.0 x 1.4" Folded Motion Tweeter and 1 x 5.25" Aluminum Woofer with a Crossover frequency at 2700Hz. On the other hand, the Motion 20i features a 1.0 x 1.4" Folded Motion Tweeter and 2 x 5.5" Aluminum Woofer with a Crossover frequency at 500Hz and 2600Hz.
Frequency Response
Motion 15i has a frequency range of 60-25k Hz whereas Motion 20i has a frequency range of 46-25k Hz. With a minimum frequency of 46Hz, the Motion 20i can go significantly deeper on the low side and provide stronger bass compared to the Motion 15i's min frequency of 60Hz.
The graph below depicts how these two speakers compare with the max, min and average Low Frequency values of other speakers in the Bookshelf class in our database.
Low Frequency
Bookshelf Speakers
Neither pair reaches down to 20Hz, the usual definition of full-range, which is normal for speakers of this size. If you want the bottom octave for movies or bass-heavy music, add a subwoofer to whichever you choose. Visit our Powered Subwoofers section to find out more about the available options.
Impedance and Sensitivity
Motion 15i is a 5 ohms speaker compared to the Motion 20i which has a nominal impedance of 4 ohms. Lower impedance speakers, especially the ones that are rated at 4 ohms may put more pressure on the amplifier unit especially when played at high volume levels, so make sure the amp you pair with the Motion 20i can provide this impedance level.
These two speakers also have different sensitivity levels. Motion 15i sensitivity is rated at 92 dB and the Motion 20i's is rated at 90 dB. This 2 dB difference makes the MartinLogan 15i a more sensitive speaker compared to MartinLogan 20i, hence will play louder with the same amount of watts.
Sensitivity
Bookshelf Speakers
Power Range
Power
range is the range of input power in watts RMS that a loudspeaker is designed to handle. Staying
within that range gives nominal performance; driving the speaker beyond its maximum wattage can damage it.
Motion 15i and Motion 20i have the same power range of 20-200 watts.
Note that higher power handling does not make a speaker louder: that depends mainly on
sensitivity and impedance. The calculator below shows how loud each of these actually plays
on a real amplifier.
Which plays louder on your amplifier?
Starting with a popular amplifier - change it to the one you own, or any you are
considering, and watch both numbers move.
Input Type and Bi-Amping / Bi-Wiring
Motion 20i features Custom 5-way bi-wire tool-less binding posts posts which make bi-amping or bi-wiring possible. Motion 15i has a Custom 5-way tool-less binding posts which doesn't feature bi-amping/bi-wiring.
MartinLogan 15i's Custom 5-way tool-less binding posts terminals
MartinLogan 20i's Custom 5-way bi-wire tool-less binding posts terminals allows Bi-amping or bi-wiring
Cabinet Type and Port Position
Both Motion 15i and Motion 20i have rear firing ports. Rear ported speakers generally need more room between the backside of the speaker and the wall compared to sealed and front/bottom ported speakers. Placing the speakers too close to the walls may cause the bass to sound boomy.
If you are limited in space and can't get the speakers away from the backwall, check our Speakers with Front Firing Ports page.
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 15i's and MartinLogan 20i's external dimensions. MartinLogan 15i has external dimensions of 290.0 x 173.0 x 240.0mm (11.4 x 6.8 x 9.4inch) whereas MartinLogan 20i has external dimensions of 905.0 x 175.0 x 307.0mm (35-5/8 x 6-7/8 x 12-1/16inch).
MartinLogan 20i is clearly the larger of the two speakers. Its body is 2mm wider, 615mm taller and 67mm deeper than MartinLogan 15i.
Below you can see the front view size comparison of MartinLogan 15i and MartinLogan 20i in scale.
Comparison image of MartinLogan 15i and MartinLogan 20i Size and External Dimensions
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 15i is approximately 415.2cm2 / 64.4inch2 and base area of the MartinLogan 20i is approximately 537.3cm2 / 83.3inch2. The Motion 15i requires 23% less surface area than the Motion 20i which gives it a small advantage on placement in tight spaces.
What's in the Box of MartinLogan 15i?
Here are the items that are included inside the box of Motion 15i:
- Bookshelf loudspeaker
- Grille
- 4 Rubber feet
- Users Manual
- Warranty/Registration Information
What's in the Box of MartinLogan 20i?
Here are the items that come with the Motion 20i:
- Floorstanding loudspeaker
- 2 Grilles
- 4 Rubber feet (pre-installed)
- 4 Spike feet (w/ nuts attached)
- Users Manual
- Warranty/Registration Information