Short answer: the XMechanik Mechano23 DIY. It ranks #6 of 87 bookshelf speakers by sound quality at $48; the KEF Q150 ranks #26 and costs $350, 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 XMechanik Mechano23 DIY offers: The bass alignment is unusually well damped, with a measured Q of 0.336, among the lowest of any speaker in this catalog, so the -3dB point at 77.6Hz rolls off cleanly instead of building into a resonant bump the way many small ported designs do. On axis deviation measures a tight 0.195dB average, and Audio Science Review’s independent Klippel NFS review called the predicted in room response nearly perfect, with directivity matching that beats some commercial designs costing many times more, all from about $200 in parts. Watch for: This is a true DIY project. There is no assembled unit to buy, drivers come from Madisound, the crossover kit comes separately from EZ Speaker Solutions, and the birch plywood cabinet has to be built and finished by hand. Listening window smoothness measures a moderate 0.47 and the sound power directivity index has more variation (standard deviation 4.02) than the tightest speakers in this catalog, so off axis energy isn’t quite as evenly controlled as the excellent on axis figures suggest.
Buy the XMechanik Mechano23 DIY. It ranks higher for sound quality than the KEF Q150 and costs less, so there is no real case for the other one.
Specifications Side By Side
| KEF Q150 | XMechanik Mechano23 DIY | |
|---|---|---|
| Price | $350 Discontinued | ~$48 each |
| Ranked | #26 of 87 in Medium Size Bookshelf Speakers | #6 of 87 in Medium Size Bookshelf Speakers |
| Bass Extension (-10dB) | 44Hz (measured, Erin’s Audio Corner) | 42.4Hz (measured, Audio Science Review) |
| Bass Extension (-3dB) | 51Hz (measured, Erin’s Audio Corner) | 77.6Hz (measured, Audio Science Review) |
| Dimensions | 11.9"H x 7.1"W x 10.9"D (303 x 180 x 278 mm) | 11.4"H x 6.9"W x 10.4"D (290 x 174 x 263 mm) (11.4 x 6.9 x 10.4 in) |
| 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) | 85.1dB @ 2.83V/1m (measured, Audio Science Review) |
| Drivers | 130mm (5.25") aluminium Uni-Q woofer, 25mm (1") vented aluminium dome tweeter | Scan-Speak Discovery H2606/9200 1" horn loaded textile dome tweeter, SB Acoustics SB13PFCR25-4 5" fiber cone woofer |
| Discontinued | Yes | - |
| Weight | 12.3 lbs / 5.6 kg each | - |
| Woofer Cabinet | ported, rear | - |
| Enclosure | - | ported |
| Port Tuning | - | Approximately 45Hz |
| Cabinet Material | - | 18mm Baltic birch plywood |
| Country | - | Design origin: United States (ASR forum); assembled by buyer |
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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
XMechanik Mechano23 DIY: ~$48 each Madisound (Tweeter) Madisound (Woofer) eBay
Pros: The bass alignment is unusually well damped, with a measured Q of 0.336, among the lowest of any speaker in this catalog, so the -3dB point at 77.6Hz rolls off cleanly instead of building into a resonant bump the way many small ported designs do. On axis deviation measures a tight 0.195dB average, and Audio Science Review’s independent Klippel NFS review called the predicted in room response nearly perfect, with directivity matching that beats some commercial designs costing many times more, all from about $200 in parts.
Cons: This is a true DIY project. There is no assembled unit to buy, drivers come from Madisound, the crossover kit comes separately from EZ Speaker Solutions, and the birch plywood cabinet has to be built and finished by hand. Listening window smoothness measures a moderate 0.47 and the sound power directivity index has more variation (standard deviation 4.02) than the tightest speakers in this catalog, so off axis energy isn’t quite as evenly controlled as the excellent on axis figures suggest.
Full XMechanik Mechano23 DIY review and specifications →
| Bass Extension (-10dB) | 42.4Hz (measured, Audio Science Review) |
|---|---|
| Bass Extension (-3dB) | 77.6Hz (measured, Audio Science Review) |
| Cabinet Material | 18mm Baltic birch plywood |
| Country | Design origin: United States (ASR forum); assembled by buyer |
| Dimensions | 11.4"H x 6.9"W x 10.4"D (290 x 174 x 263 mm) (11.4 x 6.9 x 10.4 in) |
| Drivers | Scan-Speak Discovery H2606/9200 1" horn loaded textile dome tweeter, SB Acoustics SB13PFCR25-4 5" fiber cone woofer |
| Enclosure | ported |
| Port Tuning | Approximately 45Hz |
| Sensitivity | 85.1dB @ 2.83V/1m (measured, Audio Science Review) |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons