In this review, we will be comparing two different type of speakers by MartinLogan. MartinLogan Motion 15i is a Bookshelf speaker whereas the Motion 50XTi is a Center Channel speaker.
Let's have a brief look at the main features
of MartinLogan 15i and MartinLogan 50XTi first before getting into our more
detailed comparison.
MartinLogan 15i Key Specs
- 2-way Design
- 1.0 x 1.4" Folded Motion Tweeter
- 5.25" Aluminum Woofer
- 60-25k Hz Frequency Response
- 92 dB Sensitivity
- Impedance: 5ohms
- Power Range:20-200watts
- Weight:5.40kg
- Dimensions (H x W x D): 290.0" x 6.8" x 9.4"( 290.0 x 173.0 x 240.0mm )
MartinLogan 50XTi Key Specs
- 3-way Design
- 1.25 x 2.4" Folded Motion XT Tweeter
- 2 x 6.5" Aluminum Woofer
- 50-25k Hz Frequency Response
- 94 dB Sensitivity
- Impedance: 4ohms
- Power Range:20-300watts
- Weight:13.86kg
- Dimensions (H x W x D): 196.0" x 23" x 13-5/8"( 196.0 x 585.0 x 347.0mm )
Motion 15i and Motion 50XTi 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 50XTi 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 50XTi |
| Near-field |
Poor |
Poor |
| Small Room |
Average |
Poor |
| Mid-size Room |
Good |
Good |
| Large Room |
Average |
Good |
| Very Large Room |
Poor |
Average |
(* 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.)
In the following sections, we will get into more detail in order to better understand how the MartinLogan 15i and MartinLogan 50XTi compare and hopefully end up with enough arguments to decide which one of these loudspeakers is the better choice for you.
**This post contains affiliate links, and I will be compensated if you make a purchase after clicking
through my links. As an Amazon Associate I earn from qualifying purchases.
Drivers
One of the fundamental differences between these two speakers is that Motion 15i is a 2-way design whereas the Motion 50XTi is a 3-way speaker. 3-way designs utilize a midrange driver in addition to the tweeter and woofer on 2-way designs. Designing a crossover for a 3-way speaker is a complicated process and generally increases the overall cost of the speaker.
| Driver |
MartinLogan 15i |
MartinLogan 50XTi |
|
Driver Setup
|
2-way
|
3-way
|
|
Tweeter
|
1.0 x 1.4-inch
|
1.25 x 2.4-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 5.25-inch
|
2 x 6.5-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 50XTi features a 1.25 x 2.4" Folded Motion XT Tweeter and 2 x 6.5" Aluminum Woofer with a Crossover frequency at 900Hz and 2200Hz.
Frequency Response
Motion 15i has a frequency range of 60-25k Hz whereas Motion 50XTi has a frequency range of 50-25k Hz. With a minimum frequency of 50Hz, the Motion 50XTi can go significantly deeper on the low side and provide stronger bass compared to the Motion 15i's min frequency of 60Hz.
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 Bookshelf class in our database.
Low Frequency
Bookshelf Speakers
High Frequency
Bookshelf Speakers
None of these speakers achieves full range experience which is commonly agreed as 20Hz-20kHz. In order to achieve lower lows / deeper bass, we recommend you pair these with a subwoofer. 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 50XTi 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 50XTi can provide this impedance level.
These two speakers also have different sensitivity levels. Motion 15i sensitivity is rated at 92 dB and the Motion 50XTi's is rated at 94 dB. This 2 dB difference makes the MartinLogan 50XTi a more sensitive speaker compared to MartinLogan 15i, 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. While using an amplifier within this range ensures the nominal performance , inputting a power that is higher than the max wattage can result in a damaged speaker.
Motion 15i can handle a max power of 300 watts RMS from the amp the whereas Motion 15i has a max power handling value of 200 watts RMS , 100 watts less than the Motion 50XTi.
Keep in mind that a higher max power handling value doesn't necessarily make that a louder speaker
compared to a lower max handling speaker. Loudness or the sound level is also impacted by parameters
such as Impedance, sensitivity and system efficiencies.
Input Type and Bi-Amping / Bi-Wiring
Motion 50XTi 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 50XTi'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 50XTi 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
Size of a speaker can sometimes become 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 50XTi'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 50XTi has external dimensions of 196.0 x 585.0 x 347.0mm ( 7-11/16 x 23 x 13-5/8inch) .
MartinLogan 15i is 412mm narrower and 107mm less deeper than MartinLogan 50XTi but it is also 94mm taller.
Below you can see the front view size comparison of MartinLogan 15i and MartinLogan 50XTi in scale.
Comparison image of MartinLogan 15i and MartinLogan 50XTi 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 50XTi is approximately 2030.0cm2 / 314.7inch2. The Motion 15i requires 80% less surface area than the Motion 50XTi 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 50XTi?
Here are the items that come with the Motion 50XTi:
Center-channel loudspeaker Grille 4 Rubber feet Users Manual Warranty/Registration Information
Nominal Impedance 
Base Surface Area 
Price per pair* 
Max Input Power 
Driver Setup 
Sensitivity 
Woofer Size 
Bi-Amping and Bi-Wiring 
Height