In this review, we will be comparing two different type of speakers by MartinLogan. MartinLogan Motion 8i is a Center Channel speaker whereas the Motion 20i is a Floor-standing speaker.
Let's have a brief look at the main features
of MartinLogan 8i and MartinLogan 20i first before getting into our more
detailed comparison.
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 )
MartinLogan 20i Key Specs
- 2-way Design
- 1.0 x 1.4" Folded Motion Tweeter
- 2 x 5.5" Aluminum Woofer
- 46-25k Hz Frequency Response
- 90 dB Sensitivity
- Impedance: 4ohms
- Power Range:20-200watts
- Weight:15.00kg
- Dimensions (H x W x D): 905.0" x 6-7/8" x 12-1/16"( 905.0 x 175.0 x 307.0mm )
Motion 8i 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 8i 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 8i |
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.)
In the following sections, we will get into more detail in order to better understand how the MartinLogan 8i and MartinLogan 20i 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 8i and Motion 20i are 2-way speakers.
| Driver |
MartinLogan 8i |
MartinLogan 20i |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1.0 x 1.4-inch
|
1.0 x 1.4-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
2 x 4-inch
|
2 x 5.5-inch
|
Motion 8i features a 1.0 x 1.4" Folded Motion Tweeter and 2 x 4" poly cone woofers with rigid dust caps Woofer . 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 8i has a frequency range of 70-23k 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 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 Center Channel class in our database.
Low Frequency
Center Channel Speakers
High Frequency
Center Channel 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 8i and Motion 20i have the same Impedance of 4 ohms but where they differ is the sensitivity levels. Motion 8i sensitivity is rated at 89 dB and the Motion 20i's is at 90 dB. This 1 dB difference makes the MartinLogan 20i a more sensitive speaker compared to MartinLogan 8i, hence will play louder with the same amount of watts.
One thing to keep in mind that the lower impedance speakers, especially the ones that are rated at 4 ohms may put more pressure on the amplifier unit comared to higher impedance speakers especially at high volume levels, so make sure the amp you pair with the Motion 8i and the Motion 8i can provide this impedance level.
Sensitivity
Center Channel 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 8i 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 20i.
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 20i features Custom 5-way bi-wire tool-less binding posts posts which make bi-amping or bi-wiring possible. Motion 8i has a Spring post which doesn't feature bi-amping/bi-wiring.
MartinLogan 8i's Spring post terminals
MartinLogan 20i's Custom 5-way bi-wire tool-less binding posts terminals allows Bi-amping or bi-wiring
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 8i's and MartinLogan 20i's external dimensions. 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) 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 8i is 763mm shorter and 173mm less deeper than MartinLogan 20i but it is also 387mm 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 8i is approximately 753.1cm2 / 116.7inch2 and base area of the MartinLogan 20i is approximately 537.3cm2 / 83.3inch2. The Motion 8i requires 40% more surface area than the Motion 20i which gives it a small disadvantage on placement in tight spaces.
What's in the Box of MartinLogan 8i?
Here are the items that are included inside the box of Motion 8i:
LCR loudspeakerGrille2 Wall-bracket2 Shoulder bolts4 Rubber bumpersCleaning clothUser-feets Manual (En/Fr)Installation templateProduct Registration Card
What's in the Box of MartinLogan 20i?
Here are the items that come with the Motion 20i:
Floorstanding loudspeaker2 Grilles4 Rubber feet (pre-installed)4 Spike feet (w/ nuts attached)Users ManualWarranty/Registration Information
Height 
Price per pair* 
Max Input Power 
Sensitivity 
Woofer Size 
High Frequency Response 
Base Surface Area