In this review, we will be comparing Motion 35XTi and LS50, two Passive Bookshelf speakers from MartinLogan and KEF. Let's have a brief look at the main features
of MartinLogan 35XTi and KEF LS50 first before getting into our more
detailed comparison.
What size room are the MartinLogan 35XTi and KEF LS50 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:
In the following sections, we will get into more detail in order to better understand how the MartinLogan 35XTi and KEF LS50 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 35XTi and LS50 are 2-way speakers.
| Driver |
MartinLogan 35XTi |
KEF LS50 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1.25 x 2.4-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 6.5-inch
|
1 x 5.25-inch
|
Motion 35XTi features a 1.25 x 2.4" Folded Motion XT Tweeter and 1 x 6.5" Aluminum Woofer with a Crossover frequency at 2200Hz. On the other hand, the LS50 features a 1" Aluminum Vented dome Tweeter and 1 x 5.25" Magnesium/aluminum alloy Woofer with a Crossover frequency at 2200Hz.
Frequency Response
Motion 35XTi has a frequency range of 50-25k Hz whereas LS50 has a frequency range of 79-28k Hz. With a minimum frequency of 50Hz, the Motion 35XTi can go significantly deeper on the low side and provide stronger bass compared to the LS50's min frequency of 79Hz.
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 35XTi is a 4 ohms speaker compared to the LS50 which has a nominal impedance of 8 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 35XTi can provide this impedance level.
These two speakers also have different sensitivity levels. Motion 35XTi sensitivity is rated at 92 dB and the LS50's is rated at 85 dB. This 7 dB difference makes the MartinLogan 35XTi a more sensitive speaker compared to KEF LS50, 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 35XTi can handle a max power of 250 watts RMS from the amp the whereas LS50 has a max power handling value of 100 watts RMS, 150 watts less than the Motion 35XTi.
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 35XTi features Custom 5-way bi-wire tool-less binding posts posts which make bi-amping or bi-wiring possible. LS50 has a Post which doesn't feature bi-amping/bi-wiring.
MartinLogan 35XTi's Custom 5-way bi-wire tool-less binding posts terminals allows Bi-amping or bi-wiring
KEF LS50's Post terminals
Cabinet Type and Port Position
Both Motion 35XTi and LS50 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 35XTi's and KEF LS50's external dimensions. MartinLogan 35XTi has external dimensions of 343.0 x 192.0 x 300.0mm ( 13.5 x 7.5 x 11.8inch) whereas KEF LS50 has external dimensions of 302.0 x 200.0 x 278.0mm ( 11.8 x 7.8 x 10.9inch) .
KEF LS50 is 41mm shorter and 22mm less deeper than MartinLogan 35XTi but it is also 8mm wider.
Below you can see the front view size comparison of MartinLogan 35XTi and KEF LS50 in scale.
Comparison image of MartinLogan 35XTi and KEF LS50 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 35XTi is approximately 576.0cm2 / 89.3inch2 and base area of the KEF LS50 is approximately 556.0cm2 / 86.2inch2. The Motion 35XTi requires 4% more surface area than the LS50 which gives it a small disadvantage on placement in tight spaces.
Here is an another comparison that shows both speakers on a BDI Octave Media Cabinet, next to a standard size amplifier and turntable in scale:
Size Comparison image of MartinLogan 35XTi and KEF LS50 on a Media Console
Weight Comparison The weight of a loudspeaker can become an important factor if you need to move and reposition the unit often. Weight of a speaker can also "sometimes" be an indicator of the rigidity of the enclosure and the quality of the internal components used. The MartinLogan 35XTi weighs 8.40kg / 18.5lbs and the KEF LS50 weighs 7.20kg / 15.8lbs. This makes the Motion 35XTi 17% heavier than the LS50.
Here is a comparison of how Motion 35XTi and LS50's weights compare with the average, max and min weights in Passive Bookshelf class.
Weight
All Bookshelf Speakers
What's in the Box of MartinLogan 35XTi?
Here are the items that are included inside the box of Motion 35XTi:
Bookshelf loudspeaker Grille 4 Rubber feet 2 Jumper-straps (pre-installed) Users Manual Warranty/Registration Information
What's in the Box of KEF LS50?
Here are the items that come with the LS50:
2 Bookshelf loudspeakers 2 Foam port plugs 8 Self-adhesive rubber feet Owner's Manual Warranty Registration Card
 Max Input Power |
250 watts
vs
100 watts
|
Handle more power from your amplifier |
 Sensitivity |
92 dB
vs
85 dB
|
Play louder with same amount of amplification power |
 Woofer Size |
6.5 inches
vs
5.25 inches
|
Larger woofer |
| Low Frequency Response |
50 Hz
vs
79 Hz
|
Generates deeper bass |
 Bi-Amping and Bi-Wiring |
Yes
vs
No
|
Allows bi-amping and bi-wiring connections |
 Nominal Impedance |
8 ohms
vs
4 ohms
|
Less selective with amplifiers |
 High Frequency Response |
28k Hz
vs
25k Hz
|
Generates higher frequency |
 Height |
302mm
vs
343mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
556cm2 (200x278mm)
vs
576cm2 (192x300mm)
|
Takes less floor space |
| General |
MartinLogan Motion 35XTi |
KEF LS50 |
| Brand |
MartinLogan |
KEF |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
20-250 watts |
25-100 watts |
| Sensitivity |
92 dB |
85 dB |
| Impedance |
4 ohms |
8 ohms |
| Impedance |
n/a |
3.2 ohms |
| Frequency Response |
50-25k Hz |
79-28k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
6.5" |
5.25" |
| Woofer Composition |
Aluminum |
Magnesium/aluminum alloy |
| Woofer Surround Material |
Rubber |
Rubber |
| Tweeter Size |
1.25 x 2.4" |
1" |
| Tweeter Type |
Folded Motion XT |
Vented dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
2200Hz |
2200Hz |
| Firing Direction |
rear |
rear |
| Suggested Break-in Period |
Allow 72 hours of break-in at 90 dB |
n/a |
Physical Specs |
|
|
| Height |
343.0mm (13.5") |
302.0mm (11.9") |
| Width |
192.0mm (7.6") |
200.0mm (7.9") |
| Depth |
300.0mm (11.8") |
278.0mm (10.9") |
| Weight |
8.40kg (18.5lbs) |
7.20kg (15.8lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
MDF/Lacquer |
Polymer/Lacquer |
| Available Colors |
Gloss Black, Matt White, Red Walnut |
Black, High Gloss Piano Black, High Gloss Piano White |
| Mounting Bracket |
No |
No |
| Recommended Stand Height |
24-26" |
18-28" |
| Grille |
Yes |
n/a |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
Yes |
No |
Other |
|
|
| Parts Warranty |
5 Years |
5 Years |
| Labor Warranty |
5 Years |
5 Years |