Short answer: both are discontinued, so this only matters if you are buying used. Used, the Emotiva B1+ is the better pick: it ranks #23 of 179 bookshelf speakers by sound quality (rated 4.1/5), against #48 (rated 3.7/5) for the KEF Q150. If you want one new, the Emotiva Airmotiv XB2 replaces the Emotiva B1+ and is rated 4.2/5 at $549.
The KEF Q150 is the deeper-bass option. Compact bookshelf speakers with a tweeter set in the center of the woofer, usable ported or sealed and easy to correct with EQ. Its bass reaches about 51Hz before falling 3dB, against 70Hz for the Emotiva B1+. The tradeoff: 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.
The Emotiva B1+ is the better-sounding choice. Highly rated budget bookshelf speakers with a folded ribbon tweeter, now discontinued but worth buying used. The tradeoff: It needs an external amplifier and thoughtful placement.
Buy the Emotiva B1+ only if you find one used in good condition; both are discontinued, and it is the better rated of the two. For a new speaker, buy the Emotiva Airmotiv XB2, which replaces the Emotiva B1+.
Still deciding? The full Passive Home rankings cover every ranked option.
Measured Differences
- Close enough not to matter: bass extension (44 Hz vs 49 Hz, 10 dB down).
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Specifications Side By Side
| KEF Q150 | Emotiva B1+ | |
|---|---|---|
| Price | $350 per pair Discontinued | $250 per pair Discontinued |
| Ranked | #48 of 179 in Medium Size Bookshelf Speakers | #23 of 179 in Medium Size Bookshelf Speakers |
| Bass Extension (-10dB) | 44Hz (measured, Erin’s Audio Corner) | 49Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | 51Hz (measured, Erin’s Audio Corner) | 70Hz (measured, Erin’s Audio Corner) |
| Dimensions | 11.9”H x 7.1”W x 10.9”D (303 x 180 x 278 mm) | 10.8”H x 7.1”W x 8.3”D (274 x 181 x 210 mm) |
| Impedance | 8 ohms nominal, about 4.7 ohms minimum (measured, Erin’s Audio Corner) | 8 ohms |
| Sensitivity | ~85dB (300Hz-3kHz on-axis, measured, Erin’s Audio Corner) | 85dB (measured, Erin’s Audio Corner) |
| Drivers | 130mm (5.25”) aluminium Uni-Q woofer, 25mm (1”) vented aluminium dome tweeter | 5.25” woven fiber cone with SBR surround woofer, 25x32 mm Airmotiv folded ribbon tweeter |
| Weight | 12.3 lbs (5.6 kg) each | 8.8 lbs (4.0 kg) each |
| Woofer Cabinet | ported, rear | ported, rear |
| Spinorama Preference Score | 4.86 | 5.34 (spinorama.org) |
| Spinorama Preference Score with Perfect Sub | 7.06 | 7.86 (spinorama.org) |
| DIY Kit | No | No |
Where the Ratings Come From
- KEF Q150: Spinorama.org measurements and reviews by Erin’s Audio Corner and GR-Research.
- Emotiva B1+: Spinorama.org measurements and reviews by Erin’s Audio Corner.
This comparison is generated from the ratings, specifications and measurements on each product’s own page, and it updates when that data changes. How we rank explains how each rating is decided.
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