Short answer: the KEF Q150. It ranks #26 of 87 bookshelf speakers by sound quality at $350; the MartinLogan Motion B10 ranks #36 and costs $649.99, so there is not much of a tradeoff to weigh.
What the KEF Q150 offers: Two-way coaxial (Uni-Q) design with a 1” dome tweeter and 5.25” mid-range time-aligned in a single driver assembly, available in ported or sealed configuration. Exceptional soundstage depth, a hallmark of KEF’s coaxial designs that the reviewer says few other speakers match. Bass extension reaches into kick-drum territory, respectable for a compact bookshelf speaker. Resonances present in measurements are consistent across on- and off-axis readings, meaning they can be effectively corrected with EQ. Distortion profile is essentially the same whether run sealed or ported, since a subwoofer crossover point sits above where the differences would matter anyway. At its sale price (around $300, sometimes seen at $400), the reviewer considers it a clear step up from his previous budget favorite in this range, the Emotiva B1+, mainly due to the superior soundstage depth. Watch for: A high-frequency lift in the estimated in-room response makes it sound noticeably brighter in an untreated room than in a heavily acoustically-treated one - a real preference factor depending on your room’s furnishings. A mild dip in the 1-2kHz region reduces vocal fullness somewhat. Unexplained resonances appear in measurements and persist in both sealed and ported configurations, pointing to enclosure or panel vibration rather than the port. Horizontal radiation is narrower than the reviewer generally prefers from KEF’s lineup, with directivity that widens somewhat around 1.2kHz (near a resonance) and again above about 5kHz. Compression testing at high output (102dB) shows significant nonlinearity, especially at lower frequencies - noticeably worse than a comparable Arendal bookshelf speaker costing over twice as much, which held up better until 80Hz. Not intended for loud listening without a subwoofer - the woofer will over-exert itself without a high-pass filter, and the reviewer recommends crossing over at 80-120Hz. At full retail price (around $600/pair), the value proposition is far less certain than at sale pricing.
What the MartinLogan Motion B10 offers: MartinLogan’s folded-motion tweeter technology (a 9.2 sq in diaphragm, larger than a typical dome) reaches this price point, with an excellent sound-power smoothness score of 0.111, meaning its off-axis output tracks its on-axis response unusually well. Sensitivity of 92dB makes it easy to drive. Watch for: On-axis deviation of 0.669dB is rough for the price, with a pronounced +0.32dB per octave upward tilt giving it a notably bright balance, and predicted in-room smoothness of just 0.16, the roughest of any speaker measured here. Bass extension is shallow too, a Harman in-room estimate of just 62Hz.
Buy the KEF Q150. It ranks higher for sound quality than the MartinLogan Motion B10 and costs less, so there is no real case for the other one.
Specifications Side By Side
| KEF Q150 | MartinLogan Motion B10 | |
|---|---|---|
| Price | $350 Discontinued | $649.99 each |
| Ranked | #26 of 87 in Medium Size Bookshelf Speakers | #36 of 87 in Medium Size Bookshelf Speakers |
| Bass Extension (-10dB) | 44Hz (measured, Erin’s Audio Corner) | - |
| Bass Extension (-3dB) | 51Hz (measured, Erin’s Audio Corner) | - |
| Dimensions | 11.9"H x 7.1"W x 10.9"D (303 x 180 x 278 mm) | 12.5H x 7W x 9.75D in |
| Impedance | 8 ohms nominal, about 4.7 ohms minimum (measured, Erin’s Audio Corner) | 5 ohms nominal |
| Sensitivity | ~85dB (300Hz-3kHz on-axis, measured, Erin’s Audio Corner) | 92dB |
| Drivers | 130mm (5.25") aluminium Uni-Q woofer, 25mm (1") vented aluminium dome tweeter | 1" x 1.4" Gen2 Obsidian Folded Motion tweeter, 5.5" woven fiberglass midrange |
| Discontinued | Yes | - |
| Weight | 12.3 lbs / 5.6 kg each | 14.5 lbs each |
| Woofer Cabinet | ported, rear | - |
| Enclosure | - | Rear-ported, 2-way |
| Country | - | United States (design) |
Related Speaker Comparisons
More useful head-to-heads from the same speaker class:
- Boston Acoustics A25 vs Dynaudio Emit M10
- Wharfedale Diamond 12.1 vs Boston Acoustics A25
- ELAC Uni-Fi 2.0 UB52 vs Boston Acoustics A25
- KEF Q150 vs PSB Alpha P5
- KEF Q150 vs Triangle Esprit Titus EZ
Prices on this page were last checked August 25, 2026 at 6:19 AM UTC. Product prices and availability are accurate as of that date/time and are subject to change; the price and availability shown on Amazon at the time of purchase will apply to the purchase of this product.
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The Two Speakers In Full
KEF Q150: $350 Discontinued Amazon eBay
Pros: Two-way coaxial (Uni-Q) design with a 1” dome tweeter and 5.25” mid-range time-aligned in a single driver assembly, available in ported or sealed configuration. Exceptional soundstage depth, a hallmark of KEF’s coaxial designs that the reviewer says few other speakers match. Bass extension reaches into kick-drum territory, respectable for a compact bookshelf speaker. Resonances present in measurements are consistent across on- and off-axis readings, meaning they can be effectively corrected with EQ. Distortion profile is essentially the same whether run sealed or ported, since a subwoofer crossover point sits above where the differences would matter anyway. At its sale price (around $300, sometimes seen at $400), the reviewer considers it a clear step up from his previous budget favorite in this range, the Emotiva B1+, mainly due to the superior soundstage depth.
Cons: A high-frequency lift in the estimated in-room response makes it sound noticeably brighter in an untreated room than in a heavily acoustically-treated one - a real preference factor depending on your room’s furnishings. A mild dip in the 1-2kHz region reduces vocal fullness somewhat. Unexplained resonances appear in measurements and persist in both sealed and ported configurations, pointing to enclosure or panel vibration rather than the port. Horizontal radiation is narrower than the reviewer generally prefers from KEF’s lineup, with directivity that widens somewhat around 1.2kHz (near a resonance) and again above about 5kHz. Compression testing at high output (102dB) shows significant nonlinearity, especially at lower frequencies - noticeably worse than a comparable Arendal bookshelf speaker costing over twice as much, which held up better until 80Hz. Not intended for loud listening without a subwoofer - the woofer will over-exert itself without a high-pass filter, and the reviewer recommends crossing over at 80-120Hz. At full retail price (around $600/pair), the value proposition is far less certain than at sale pricing. Discontinued.
Full KEF Q150 review and specifications →
| Bass Extension (-10dB) | 44Hz (measured, Erin's Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 51Hz (measured, Erin's Audio Corner) |
| Dimensions | 11.9"H x 7.1"W x 10.9"D (303 x 180 x 278 mm) |
| Discontinued | Yes |
| Drivers | 130mm (5.25") aluminium Uni-Q woofer, 25mm (1") vented aluminium dome tweeter |
| Impedance | 8 ohms nominal, about 4.7 ohms minimum (measured, Erin's Audio Corner) |
| Sensitivity | ~85dB (300Hz-3kHz on-axis, measured, Erin's Audio Corner) |
| Weight | 12.3 lbs / 5.6 kg each |
| Woofer Cabinet | ported, rear |
- Links
- Reviews, Comparisons and Sound Samples
- Erin’s Audio Corner: Kef’s Cheapest Bookshelf. Is the Q150 worth your money? More from Erin’s Audio Corner →
- Erin’s Audio Corner Website KEF Q150
- GR-Research: KEF Q150… can it get any BETTER? More from GR-Research →
- Erin’s Audio Corner: 5 AWESOME SPEAKERS Under $1000 You Won’t Regret
- Erin’s Audio Corner: Budget Stereo Systems You Will Love
- Erin’s Audio Corner Measurements (spinorama.org)
- Reddit Search for KEF Q150 Review
- Head-to-Head Comparisons
MartinLogan Motion B10: $649.99 each Crutchfield eBay
Pros: MartinLogan’s folded-motion tweeter technology (a 9.2 sq in diaphragm, larger than a typical dome) reaches this price point, with an excellent sound-power smoothness score of 0.111, meaning its off-axis output tracks its on-axis response unusually well. Sensitivity of 92dB makes it easy to drive.
Cons: On-axis deviation of 0.669dB is rough for the price, with a pronounced +0.32dB per octave upward tilt giving it a notably bright balance, and predicted in-room smoothness of just 0.16, the roughest of any speaker measured here. Bass extension is shallow too, a Harman in-room estimate of just 62Hz.
Full MartinLogan Motion B10 review and specifications →
| Country | United States (design) |
|---|---|
| Dimensions | 12.5H x 7W x 9.75D in |
| Drivers | 1" x 1.4" Gen2 Obsidian Folded Motion tweeter, 5.5" woven fiberglass midrange |
| Enclosure | Rear-ported, 2-way |
| Impedance | 5 ohms nominal |
| Sensitivity | 92dB |
| Weight | 14.5 lbs each |
- Links
- Reviews, Comparisons and Sound Samples