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MartinLogan 20i vs MartinLogan 15i Comparison

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MartinLogan 20i

Passive Floor-standing | 46-25k Hz

MartinLogan Motion 20i
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MartinLogan 15i

Passive Bookshelf | 60-25k Hz

MartinLogan Motion 15i
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MartinLogan 20i MartinLogan 20i
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MartinLogan 15i MartinLogan 15i
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MartinLogan 20i
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MartinLogan 15i
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MartinLogan 20i vs MartinLogan 15i Speaker Comparison

In this review, we will be comparing two different type of speakers by MartinLogan. MartinLogan Motion 20i is a Floor-standing speaker whereas the Motion 15i is a Bookshelf speaker.

Let's have a brief look at the main features of MartinLogan 20i and MartinLogan 15i first before getting into our more detailed comparison.

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 )

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 )

Motion 20i and Motion 15i are members of MartinLogan's Motion series of speakers. Below you can find the loudspeakers from this series.

MartinLogan Motion Series History
Model Body Frequency SensitivityImpedance Woofer
MartinLogan 15i
Bookshelf 60-25k Hz 92 dB5Ω 1 x 5.25"
MartinLogan 35XTi
  
Bookshelf 50-25k Hz 92 dB4Ω 1 x 6.5"
MartinLogan 60XTi
  
Floor-standing 35-25k Hz 94 dB4Ω 2 x 8"
MartinLogan 50XTi
  
Center Channel 50-25k Hz 94 dB4Ω 2 x 6.5"
MartinLogan LX16
  
Bookshelf 60-25k Hz 92 dB5Ω 1 x 5.25"
MartinLogan 40i
  
Floor-standing 40-25k Hz 92 dB4Ω 2 x 6.5"
MartinLogan 20i
Floor-standing 46-25k Hz 90 dB4Ω 2 x 5.5"
MartinLogan 30i
  
Center Channel 65-25k Hz 91 dB4Ω 1 x 5.25"
MartinLogan 6i
  
Center Channel 120-23k Hz 89 dB6Ω 2 x 3.5"
MartinLogan 8i
  
Center Channel 70-23k Hz 89 dB4Ω 2 x 4"

What size room are the MartinLogan 20i and MartinLogan 15i 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 20i MartinLogan 15i
Near-field Bad Poor
Small Room Poor Average
Mid-size Room Good Good
Large Room Good 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 20i and MartinLogan 15i 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

Both Motion 20i and Motion 15i are 2-way speakers.

Driver MartinLogan 20i MartinLogan 15i
Driver Setup 2-way 2-way
Tweeter 1.0 x 1.4-inch 1.0 x 1.4-inch
Midrange - -
Woofer 2 x 5.5-inch 1 x 5.25-inch

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. On the other hand, the 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.

Frequency Response

Motion 20i has a frequency range of 46-25k Hz whereas Motion 15i has a frequency range of 60-25k 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.

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 Floor-standing class in our database.

Low Frequency

Floor-standing Speakers

Motion 20i
Motion 15i
Min
Average
Max
High Frequency

Floor-standing Speakers

MartinLogan 20i
MartinLogan 15i
Min
Average
Max

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 20i is a 4 ohms speaker compared to the Motion 15i which has a nominal impedance of 5 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 20i sensitivity is rated at 90 dB and the Motion 15i's is rated at 92 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

Floor-standing Speakers

Motion 20i
Motion 15i
Min
Average
Max

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 20i and Motion 15i has the same power range of 20-200 watts.

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 15i has a Custom 5-way tool-less binding posts which doesn't feature bi-amping/bi-wiring.

MartinLogan 20i Terminals
MartinLogan 20i's Custom 5-way bi-wire tool-less binding posts terminals allows Bi-amping or bi-wiring

MartinLogan 15i Terminals
MartinLogan 15i's Custom 5-way tool-less binding posts terminals

Cabinet Type and Port Position

Both Motion 20i and Motion 15i 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 20i's and MartinLogan 15i's external dimensions. 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) whereas MartinLogan 15i has external dimensions of 290.0 x 173.0 x 240.0mm ( 11.4 x 6.8 x 9.4inch) .

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 20i and MartinLogan 15i in scale.

MartinLogan 20i vs MartinLogan 15i Size Comparison - Front View
Comparison image of MartinLogan 20i and MartinLogan 15i 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 20i is approximately 537.3cm2 / 83.3inch2 and base area of the MartinLogan 15i is approximately 415.2cm2 / 64.4inch2. The Motion 20i requires 29% more surface area than the Motion 15i which gives it a small disadvantage on placement in tight spaces.

What's in the Box of MartinLogan 20i?

Here are the items that are included inside the box of Motion 20i:
  • Floorstanding loudspeaker
  • 2 Grilles
  • 4 Rubber feet (pre-installed)
  • 4 Spike feet (w/ nuts attached)
  • Users Manual
  • Warranty/Registration Information
  • What's in the Box of MartinLogan 15i?

    Here are the items that come with the Motion 15i:
  • Bookshelf loudspeaker
  • Grille
  • 4 Rubber feet
  • Users Manual
  • Warranty/Registration Information

  • Reasons to choose MartinLogan Motion 20i over MartinLogan Motion 15i
    Woofer Size 5.5 inches vs 5.25 inches Larger woofer
    Number of Woofers 2 vs 1 More woofers
    Low Frequency Response 46 Hz vs 60 Hz Generates deeper bass
    Bi-Amping and Bi-Wiring Yes vs No Allows bi-amping and bi-wiring connections

    Reasons to choose MartinLogan Motion 15i over MartinLogan Motion 20i

    Sensitivity 92 dB vs 90 dB Play louder with same amount of amplification power
    Nominal Impedance 5 ohms vs 4 ohms Less selective with amplifiers
    Height 290mm vs 905mm Easier to fit in smaller spaces
    Base Surface Area 415cm2 vs 537cm2 Takes less floor space
    Price per pair* 900USD vs 2000USD costs less (*prices may change depending on the seller, location and time)
    MartinLogan 20i vs MartinLogan 15i Specs Table
    Detailed comparison of specifications
    General MartinLogan Motion 20i MartinLogan Motion 15i
    Brand MartinLogan MartinLogan
    Speaker Type Floor-standing speaker Bookshelf speakers
    Power Range 20-200 watts 20-200 watts
    Sensitivity 90 dB 92 dB
    Impedance 4 ohms 5 ohms
    Frequency Response 46-25k Hz 60-25k Hz
    Drivers
    Woofer Quantity 2 1
    Woofer Size 5.5" 5.25"
    Woofer Composition Aluminum Aluminum
    Woofer Surround Material Rubber Rubber
    Tweeter Size 1.0 x 1.4" 1.0 x 1.4"
    Tweeter Type Folded Motion Folded Motion
    Aimable Tweeter No No
    Midrange Driver No No
    Crossover Frequency 500Hz and 2600Hz 2700Hz
    Firing Direction rear rear
    Suggested Break-in Period Allow 72 hours of break-in at 90 dB Allow 72 hours of break-in at 90 dB
    Physical Specs
    Height 905.0mm (35.6") 290.0mm (11.4")
    Width 175.0mm (6.9") 173.0mm (6.8")
    Depth 307.0mm (12.1") 240.0mm (9.4")
    Weight 15.00kg (33lbs) 5.40kg (11.9lbs)
    Enclosure Bass Reflex Bass Reflex
    Finish MDF/Lacquer MDF/Lacquer
    Available Colors Gloss Black, Matt White, Red Walnut Gloss Black, Matt White, Red Walnut
    Mounting Bracket No No
    Recommended Stand Height n/a 26-28"
    Grille Yes Yes
    Moisture Resistancy No No
    Connections
    Biamp Inputs Yes No
    Other
    Parts Warranty 5 Years 5 Years
    Labor Warranty 5 Years 5 Years

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