In this review, we will be comparing two different type of speakers by MartinLogan. MartinLogan Motion 15i is a Bookshelf speaker whereas the Motion 8i is a Center Channel speaker.
Let's have a brief look at the main features
of MartinLogan 15i and MartinLogan 8i 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 8i Key Specs
- 2-way Design
- 1.0 x 1.4" Folded Motion Tweeter
- 2 x 4" poly cone woofers with rigid dust caps Woofer
- 70-23k Hz Frequency Response
- 89 dB Sensitivity
- Impedance: 4ohms
- Power Range:20-180watts
- Weight:3.86kg
- Dimensions (H x W x D): 142.0" x 22-1/8" x 5-1/4"( 142.0 x 562.0 x 134.0mm )
Motion 15i and Motion 8i 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 8i 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 8i |
| Near-field |
Poor |
Poor |
| Small Room |
Average |
Average |
| Mid-size Room |
Good |
Good |
| Large Room |
Average |
Average |
| 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.)
In the following sections, we will get into more detail in order to better understand how the MartinLogan 15i and MartinLogan 8i compare and hopefully end up with enough arguments to decide which one of these loudspeakers is the better choice for you.
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Drivers
Both Motion 15i and Motion 8i are 2-way speakers.
| Driver |
MartinLogan 15i |
MartinLogan 8i |
|
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 4-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 8i features a 1.0 x 1.4" Folded Motion Tweeter and 2 x 4" poly cone woofers with rigid dust caps Woofer .
Frequency Response
Motion 15i has a frequency range of 60-25k Hz whereas Motion 8i has a frequency range of 70-23k Hz. With a minimum frequency of 60Hz, the Motion 15i can go significantly deeper on the low side and provide stronger bass compared to the Motion 8i's min frequency of 70Hz.
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 8i 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 8i can provide this impedance level.
These two speakers also have different sensitivity levels. Motion 15i sensitivity is rated at 92 dB and the Motion 8i's is rated at 89 dB. This 3 dB difference makes the MartinLogan 15i a more sensitive speaker compared to MartinLogan 8i, 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 200 watts RMS from the amp the whereas Motion 8i has a max power handling value of 180 watts RMS, 20 watts less than the Motion 15i.
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 15i features Spring post type posts and Motion 8i has a Spring post type posts. None of these speakers feature bi-amping/bi-wiring.
MartinLogan 15i's Custom 5-way tool-less binding posts terminals
MartinLogan 8i's Spring post terminals
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 8i'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 8i has external dimensions of 142.0 x 562.0 x 134.0mm ( 5-9/16 x 22-1/8 x 5-1/4inch) .
MartinLogan 8i is 148mm shorter and 106mm less deeper than MartinLogan 15i but it is also 389mm wider.
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 8i is approximately 753.1cm2 / 116.7inch2. The Motion 15i requires 45% less surface area than the Motion 8i 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 8i?
Here are the items that come with the Motion 8i:
LCR loudspeakerGrille2 Wall-bracket2 Shoulder bolts4 Rubber bumpersCleaning clothUser-feets Manual (En/Fr)Installation templateProduct Registration Card
Max Input Power 
Sensitivity 
Nominal Impedance 
Woofer Size 
High Frequency Response 
Base Surface Area 
Height 
Price per pair*