In this review, we will be comparing MartinLogan Foundation B2 and Q150, two Passive Bookshelf speakers from MartinLogan and KEF. Let's have a brief look at the main features
of MartinLogan Foundation B2 and KEF Q150 first before getting into our more
detailed comparison.
What size room are the MartinLogan Foundation B2 and KEF Q150 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 Foundation B2 and KEF Q150 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 MartinLogan Foundation B2 and Q150 are 2-way speakers.
| Driver |
MartinLogan Foundation B2 |
KEF Q150 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
1-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 6-1/2-inch
|
1 x 5.25-inch
|
MartinLogan Foundation B2 features a 1" Gen2 Obsidian Folded Motion Ribbon Tweeter and 1 x 6-1/2" Aluminum Woofer with a Crossover frequency at 3800Hz. On the other hand, the Q150 features a 1" vented aluminum Dome Tweeter and 1 x 5.25" Aluminum Woofer with a Crossover frequency at 2500Hz.
Frequency Response
MartinLogan Foundation B2 has a frequency range of 42-23k Hz whereas Q150 has a frequency range of 51-28k Hz. With a minimum frequency of 42Hz, the MartinLogan Foundation B2 can go significantly deeper on the low side and provide stronger bass compared to the Q150's min frequency of 51Hz.
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
MartinLogan Foundation B2
High Frequency
Bookshelf Speakers
MartinLogan Foundation B2
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
MartinLogan Foundation B2 is a 5 ohms speaker compared to the Q150 which has a nominal impedance of 8 ohms.
These two speakers also have different sensitivity levels. MartinLogan Foundation B2 sensitivity is rated at 90 dB and the Q150's is rated at 86 dB. This 4 dB difference makes the MartinLogan Foundation B2 a more sensitive speaker compared to KEF Q150, hence will play louder with the same amount of watts.
Sensitivity
Bookshelf Speakers
MartinLogan Foundation B2
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.
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
MartinLogan Foundation B2 features Post type posts and Q150 has a Post type posts. None of these speakers feature bi-amping/bi-wiring.
MartinLogan Foundation B2's Binding post terminals
KEF Q150's Post terminals
Cabinet Type and Port Position
Both MartinLogan Foundation B2 and Q150 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.
KEF Q150 Port
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 Foundation B2's and KEF Q150's external dimensions. MartinLogan Foundation B2 has external dimensions of 381.0 x 197.0 x 242.0mm ( 15inch x 7-3/4inch x 9-1/2inch ) whereas KEF Q150 has external dimensions of 303.0 x 180.0 x 278.0mm ( 11.9 x 7.0 x 10.9inch) .
KEF Q150 is 17mm narrower and 78mm shorter than MartinLogan Foundation B2 but it is also 36mm deeper.
Below you can see the front view size comparison of MartinLogan Foundation B2 and KEF Q150 in scale.
Comparison image of MartinLogan Foundation B2 and KEF Q150 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 Foundation B2 is approximately 476.7cm2 / 73.9inch2 and base area of the KEF Q150 is approximately 500.4cm2 / 77.6inch2. The MartinLogan Foundation B2 requires 5% less surface area than the Q150 which gives it a small advantage 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 Foundation B2 and KEF Q150 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 Foundation B2 weighs 5.23kg / 11.5lbs and the KEF Q150 weighs 5.60kg / 12.3lbs. This makes the Q150 7% heavier than the MartinLogan Foundation B2.
Here is a comparison of how MartinLogan Foundation B2 and Q150's weights compare with the average, max and min weights in Passive Bookshelf class.
Weight
All Bookshelf Speakers
MartinLogan Foundation B2
What's in the Box of KEF Q150?
Here are the items that come with the Q150:
2 Bookshelf loudspeakers 2 Foam port plugs 8 Self-adhesive rubber feet Owner's Manual Warranty Registration Card
 Sensitivity |
90 dB
vs
86 dB
|
Play louder with same amount of amplification power |
 Woofer Size |
6-1/2 inches
vs
5.25 inches
|
Larger woofer |
| Low Frequency Response |
42 Hz
vs
51 Hz
|
Generates deeper bass |
 Base Surface Area |
476cm2 (197x242mm)
vs
500cm2 (180x278mm)
|
Takes less floor space |
 Nominal Impedance |
8 ohms
vs
5 ohms
|
Less selective with amplifiers |
 High Frequency Response |
28k Hz
vs
23k Hz
|
Generates higher frequency |
 Height |
303mm
vs
381mm
|
Easier to fit in smaller spaces |
 Price per pair* |
600USD
vs
799USD
|
costs less (*prices may change depending on the seller, location and time) |
| General |
MartinLogan Foundation B2 |
KEF Q150 |
| Brand |
MartinLogan |
KEF |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
up to 100 watts |
10-100 watts |
| Sensitivity |
90 dB |
86 dB |
| Impedance |
5 ohms |
8 ohms |
| Impedance |
n/a |
3.7 ohms |
| Frequency Response |
42-23k Hz |
51-28k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
6-1/2" |
5.25" |
| Woofer Composition |
Aluminum |
Aluminum |
| Woofer Surround Material |
n/a |
Rubber |
| Tweeter Size |
1" |
1" |
| Tweeter Type |
Folded Motion Ribbon |
Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
3800Hz |
2500Hz |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
381.0mm (15") |
303.0mm (11.9") |
| Width |
197.0mm (7.8") |
180.0mm (7.1") |
| Depth |
242.0mm (9.5") |
278.0mm (10.9") |
| Weight |
5.23kg (11.5lbs) |
5.60kg (12.3lbs) |
| Enclosure |
Bass Reflex |
Bass Reflex |
| Finish |
n/a |
MDF/Vinyl-wrapped |
| Available Colors |
Walnut,Black,Satin White |
Black, Walnut, White |
| Mounting Bracket |
|
No |
| Recommended Stand Height |
n/a |
18-24" |
| Grille |
Yes |
Yes |
| Moisture Resistancy |
No |
No |
Connections |
|
|
| Biamp Inputs |
No |
No |
Other |
|
|
| Parts Warranty |
5 years |
5 Years |
| Labor Warranty |
5 years |
5 Years |