In this review, we will be comparing Airmotiv B2+ and Q150, two Passive Bookshelf speakers from Emotiva and KEF.
Let's have a brief look at the main features
of Emotiva Airmotiv B2+ and KEF Q150 first before getting into our more
detailed comparison.
| Key Specs | Emotiva Airmotiv B2+ | KEF Q150 |
|---|
| Brand | Emotiva
United States · founded 2003 | KEF
United Kingdom · founded 1961 |
|---|
| Design | 2-way | 2-way |
|---|
| Uni-Q driver | — | 11th Generation Uni-Q |
|---|
| Tweeter | 25×32 mm" folded ribbon | 1" Dome |
|---|
| Woofer | 6.25" woven fiber cone | 5.25" Aluminum |
|---|
| Frequency response | 40-28k Hz | 51-28k Hz |
|---|
| Sensitivity | 86 dB | 86 dB |
|---|
| Impedance | 4 ohms | 8 ohms |
|---|
| Power range | Up to 125 watts | 10-100 watts |
|---|
| Weight | 7.10kg / 15.6lbs | 5.60kg / 12.3lbs |
|---|
| Dimensions (H x W x D) | 12-3/4" x 8-1/2" x 11-1/2"
324.0 x 216.0 x 293.0mm | 11.9" x 7.0" x 10.9"
303.0 x 180.0 x 278.0mm |
|---|
What size room are the Emotiva Airmotiv 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:
| Listening Environment* |
Emotiva Airmotiv B2+ |
KEF Q150 |
| Near-field |
Average |
Average |
| Small Room |
Good |
Good |
| Mid-size Room |
Average |
Average |
| Large Room |
Poor |
Poor |
| Very Large Room |
Bad |
Bad |
(* 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.)
The sections below take each area in turn: drivers, frequency response, physical size and what you get in the box.
Drivers
Both Airmotiv B2+ and Q150 are 2-way speakers.
Emotiva Airmotiv B2+KEF Q150
TweeterWoofer
Front view, drawn to scale - cabinets and drivers share one scale, so sizes are directly comparable. Hover a driver for its size.
| Driver |
Emotiva Airmotiv B2+ |
KEF Q150 |
|
Driver Setup
|
2-way
|
2-way
|
|
Tweeter
|
25×32 mm-inch
|
1-inch
|
|
Midrange
|
- |
- |
|
Woofer
|
1 x 6.25-inch
|
1 x 5.25-inch
|
Airmotiv B2+ features a 25×32 mm" folded ribbon Tweeter and 1 x 6.25" woven fiber cone Woofer with a Crossover frequency at 2000Hz. 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
Airmotiv B2+ has a frequency range of 40-28k Hz whereas Q150 has a frequency range of 51-28k Hz. With a minimum frequency of 40Hz, the Airmotiv B2+ can go significantly deeper on the low side and provide stronger bass compared to the Q150's min frequency of 51Hz.
The graph below depicts how these two speakers compare with the max, min and average Low Frequency values of other speakers in the Bookshelf class in our database.
Low Frequency
Bookshelf Speakers
Neither pair reaches down to 20Hz, the usual definition of full-range, which is normal for speakers of this size. If you want the bottom octave for movies or bass-heavy music, add a subwoofer to whichever you choose. Visit our Powered Subwoofers section to find out more about the available options.
Impedance and Sensitivity
Airmotiv B2+ is a 4 ohms speaker compared to the Q150 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 Airmotiv B2+ can provide this impedance level.
On the other hand, they have the same sensitivity of 86 dBdB.
Sensitivity
Bookshelf Speakers
Power Range
Power
range is the range of input power in watts RMS that a loudspeaker is designed to handle. Staying
within that range gives nominal performance; driving the speaker beyond its maximum wattage can damage it.
Airmotiv B2+ can handle a max power of 125 watts RMS, whereas Q150 has a max power handling value of 100 watts RMS, 25 watts less than the Airmotiv B2+.
Note that higher power handling does not make a speaker louder: that depends mainly on
sensitivity and impedance. The calculator below shows how loud each of these actually plays
on a real amplifier.
Which plays louder on your amplifier?
Starting with a popular amplifier - change it to the one you own, or any you are
considering, and watch both numbers move.
Input Type and Bi-Amping / Bi-Wiring
Airmotiv B2+ features Binding post posts which make bi-amping or bi-wiring possible. Q150 has a Post which doesn't feature bi-amping/bi-wiring.
Emotiva Airmotiv B2+'s Binding post terminals allows Bi-amping or bi-wiring
KEF Q150's Post terminals
Cabinet Type and Port Position
Both Airmotiv 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.
Emotiva Airmotiv B2+ Port
KEF Q150 Port
Physical Specs
The size of a speaker can sometimes be an important decision factor due to space constraints or in some cases purely for esthetic reasons. In this section, we are going to compare Emotiva Airmotiv B2+'s and KEF Q150's external dimensions. Emotiva Airmotiv B2+ has external dimensions of 324.0 x 216.0 x 293.0mm (12-3/4-inch x 8-1/2-inch x 11-1/2-inch) whereas KEF Q150 has external dimensions of 303.0 x 180.0 x 278.0mm (11.9 x 7.0 x 10.9inch).
Emotiva Airmotiv B2+ is clearly the larger of the two speakers. Its body is 36mm wider, 21mm taller and 15mm deeper than KEF Q150.
Below you can see the front view size comparison of Emotiva Airmotiv B2+ and KEF Q150 in scale.
Comparison image of Emotiva Airmotiv 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 Emotiva Airmotiv B2+ is approximately 632.9cm2 / 98.1inch2 and base area of the KEF Q150 is approximately 500.4cm2 / 77.6inch2. The Airmotiv B2+ requires 26% more surface area than the Q150 which gives it a small disadvantage on placement in tight spaces.
Here is 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 Emotiva Airmotiv 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 Emotiva Airmotiv B2+ weighs 7.10kg / 15.6lbs and the KEF Q150 weighs 5.60kg / 12.3lbs. This makes the Airmotiv B2+ 27% heavier than the Q150.
Here is a comparison of how Airmotiv B2+ and Q150's weights compare with the average, max and min weights in Passive Bookshelf class.
Weight
All Bookshelf Speakers
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
 Max Input Power |
125 watts
vs
100 watts
|
Handle more power from your amplifier |
 Woofer Size |
6.25 inches
vs
5.25 inches
|
Larger woofer |
|
Low Frequency Response |
40 Hz
vs
51 Hz
|
Generates deeper bass |
 Bi-Amping and Bi-Wiring |
Yes
vs
No
|
Allows bi-amping and bi-wiring connections |
 Price per pair* |
499USD
vs
600USD
|
costs less (*prices may change depending on the seller, location and time) |
 Nominal Impedance |
8 ohms
vs
4 ohms
|
Less selective with amplifiers |
 Height |
303mm
vs
324mm
|
Easier to fit in smaller spaces |
 Base Surface Area |
500cm2
vs
632cm2
|
Takes less floor space |
| General |
Emotiva Airmotiv B2+ |
KEF Q150 |
| Brand |
Emotiva |
KEF |
| Speaker Type |
Bookshelf speakers |
Bookshelf speakers |
| Power Range |
Up to 125 watts |
10-100 watts |
| Sensitivity |
86 dB |
86 dB |
| Impedance |
4 ohms |
8 ohms |
| Impedance |
n/a |
3.7 ohms |
| Frequency Response |
40-28k Hz |
51-28k Hz |
Drivers |
|
|
| Woofer Quantity |
1 |
1 |
| Woofer Size |
6.25" |
5.25" |
| Woofer Composition |
woven fiber cone |
Aluminum |
| Woofer Surround Material |
SBR |
Rubber |
| Tweeter Size |
25×32 mm" |
1" |
| Tweeter Type |
folded ribbon |
Dome |
| Aimable Tweeter |
No |
No |
| Midrange Driver |
No |
No |
| Crossover Frequency |
2000Hz |
2500Hz |
| Firing Direction |
rear |
rear |
Physical Specs |
|
|
| Height |
324.0mm (12.8") |
303.0mm (11.9") |
| Width |
216.0mm (8.5") |
180.0mm (7.1") |
| Depth |
293.0mm (11.5") |
278.0mm (10.9") |
| Weight |
7.10kg (15.6lbs) |
5.60kg (12.3lbs) |
| Enclosure |
Bass reflex |
Bass Reflex |
| Finish |
HDF |
MDF/Vinyl-wrapped |
| Available Colors |
Black |
Black, Walnut, White |
| Mounting Bracket |
No |
No |
| Recommended Stand Height |
n/a |
18-24" |
| 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 |
No single best speaker here - they are built to different priorities, and the right one depends on your room, your amplifier and what you listen to.
| Area | Better | Why |
|---|
| Bass | A | Emotiva Airmotiv B2+ digs deeper - 40Hz against 51Hz. |
| Amplifier needs | evenly matched | Similar sensitivity (86dB vs 86dB) - both want much the same power. |
| Amplifier match | B | KEF Q150 is the easier load at 8 ohms; the other is 4 ohms and wants an amplifier rated for it. |
| Headroom | A | Emotiva Airmotiv B2+ takes more power (125W vs 100W) - more in hand in a big room. |
| Size | depends | KEF Q150 is easier to place; Emotiva Airmotiv B2+ is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | A | Emotiva Airmotiv B2+: bi-amping. |
| Price | A | Emotiva Airmotiv B2+ is cheaper - $499 against $600, about 17% less. |
A Emotiva Airmotiv B2+ B KEF Q150
depends neither is better in the abstract - it turns on your room, your system or how you will use them. Only specs published for both speakers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
Emotiva Airmotiv B2+ is the easier recommendation: it leads on most of the measured areas and costs less. Take KEF Q150 if its size, looks or fit in your room suit you better. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 51Hz anyway, so judge these on the other rows instead. If your amplifier is modest, vintage or valve-based, KEF Q150 is the safer partner - the other will want more current or more watts to sound its best.
And remember what a spec sheet cannot show: how each looks in your room and whether the finish suits it, what dealer support and warranty are like where you live, and how they actually sound to you. If you can hear them first - ideally with your own music - that will tell you more than any number above.