Short answer: the AsciLab C6B for better sound quality, the KEF Q350 for the lower price. The AsciLab C6B ranks #7 of 131 bookshelf speakers at $1145. The KEF Q350 ranks #106 at $699, $446 cheaper.
What the KEF Q350 offers: CEA2034 spinorama shows a reasonably flat on-axis response with excellent directivity, aided by the coaxial Uni-Q driver. Vertical directivity is better than most non-coaxial two-way speakers, another benefit of the concentric design. Watch for: Two resonances at 700Hz and 1.2kHz show up on-axis, alongside an upper-bass boost. Predicted in-room response looks a bit boomy as a result. Distortion climbs substantially in the 100Hz-1kHz range at 96dB SPL/1m, with a distinct resonance-driven peak around 900Hz-1kHz at both test levels.
What the AsciLab C6B offers: Two-way design pairing a 1” aluminum ceramic dome tweeter on a large waveguide with a 6” aluminum ceramic cone woofer, crossed over at 1.1kHz, plus a rear passive radiator. Unusual trait: horizontal radiation actually widens at higher frequencies instead of narrowing like most two-way designs, which keeps image focus and soundstage depth consistent whether you toe the speakers in or out (5-10° off-axis was the sweet spot in testing). Vertical radiation also stays wide straight through the 2kHz crossover region, so the sound doesn’t collapse when standing up - unusual at this price. CA2034 measurements show strong on-axis linearity, listening window, early reflections, and directivity. Midrange and tweeter distortion stay very low even at 96dB, holding up against a $5,900 Arendal speaker in that regard despite roughly a 5x price gap. At $935 (about $1,135 shipped to the US), the reviewer calls it the best-value bookshelf speaker he’s tested, rivaling speakers 2-5x the price. Watch for: Bass rolls off around 50Hz in-room (F3 54Hz, F10 35Hz), so a subwoofer is needed for real extension below that. Low-frequency harmonic distortion increases substantially at 96dB versus 86dB, though it’s second-order and less audible than it looks on paper. Minimum impedance dips to 2.6 ohms (EPDR as low as 1.2 ohms), so it wants an amplifier comfortable driving 4-ohm loads, ideally 100W or more. At 102dB, compression noticeably eats into midrange, bass, and some treble output. Shipping to the US adds roughly $200 on top of the $935 price. Against the reviewer’s reference Audiofirst Fidelia at a similar price, has slightly less lower-midrange body (about 1dB difference) and a smaller perceived soundstage size.
Buy the KEF Q350 if the price matters more than sound quality. Buy the AsciLab C6B if sound quality matters more than the price.
If sound quality matters at all to you, skip the KEF Q350. It ranks near the bottom of the 131 bookshelf speakers, so look higher up the list instead.
Specifications Side By Side
| KEF Q350 | AsciLab C6B | |
|---|---|---|
| Price | $699.00 Discontinued | $1145 |
| Ranked | #106 of 131 in Large Size Bookshelf Speakers | #7 of 131 in Large Size Bookshelf Speakers |
| Bass Extension (-10dB) | 38Hz (measured, Audio Science Review) | 35Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | 70Hz (measured, Audio Science Review) | 54Hz (measured, Erin’s Audio Corner) |
| Impedance | 4 ohms | 4 ohms nominal, 2.6 ohms minimum (measured, Erin’s Audio Corner) |
| Sensitivity | 86dB (measured, Audio Science Review) | 85.6dB (measured, Erin’s Audio Corner) |
| Drivers | 25mm tweeter + 165mm woofer | 6" Aluminium Ceramic Cone with cast Aluminium Chassis woofer, 1" Aluminium Ceramic Dome tweeter |
| Discontinued | Yes | - |
| Weight | 29.5 lbs / 13.4 kg | 18.5 lbs / 8.4 kg each |
| Dimensions | 14.1"H x 8.3"W x 12"D (358.0 x 210.0 x 306.0 mm) | 15.7"H x 8"W x 10.4"D (398.8 x 203.2 x 264.2 mm) |
| Woofer Cabinet | ported, rear | passive radiator |
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The Two Speakers In Full
KEF Q350: $699.00 Discontinued Amazon eBay
Pros: CEA2034 spinorama shows a reasonably flat on-axis response with excellent directivity, aided by the coaxial Uni-Q driver. Vertical directivity is better than most non-coaxial two-way speakers, another benefit of the concentric design.
Cons: Two resonances at 700Hz and 1.2kHz show up on-axis, alongside an upper-bass boost. Predicted in-room response looks a bit boomy as a result. Distortion climbs substantially in the 100Hz-1kHz range at 96dB SPL/1m, with a distinct resonance-driven peak around 900Hz-1kHz at both test levels. Discontinued.
Full KEF Q350 review and specifications →
| Bass Extension (-10dB) | 38Hz (measured, Audio Science Review) |
|---|---|
| Bass Extension (-3dB) | 70Hz (measured, Audio Science Review) |
| Dimensions | 14.1"H x 8.3"W x 12"D (358.0 x 210.0 x 306.0 mm) |
| Discontinued | Yes |
| Drivers | 25mm tweeter + 165mm woofer |
| Impedance | 4 ohms |
| Sensitivity | 86dB (measured, Audio Science Review) |
| Weight | 29.5 lbs / 13.4 kg |
| Woofer Cabinet | ported, rear |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
AsciLab C6B: $1145 Ascilab eBay
Pros: Two-way design pairing a 1” aluminum ceramic dome tweeter on a large waveguide with a 6” aluminum ceramic cone woofer, crossed over at 1.1kHz, plus a rear passive radiator. Unusual trait: horizontal radiation actually widens at higher frequencies instead of narrowing like most two-way designs, which keeps image focus and soundstage depth consistent whether you toe the speakers in or out (5-10° off-axis was the sweet spot in testing). Vertical radiation also stays wide straight through the 2kHz crossover region, so the sound doesn’t collapse when standing up - unusual at this price. CA2034 measurements show strong on-axis linearity, listening window, early reflections, and directivity. Midrange and tweeter distortion stay very low even at 96dB, holding up against a $5,900 Arendal speaker in that regard despite roughly a 5x price gap. At $935 (about $1,135 shipped to the US), the reviewer calls it the best-value bookshelf speaker he’s tested, rivaling speakers 2-5x the price.
Cons: Bass rolls off around 50Hz in-room (F3 54Hz, F10 35Hz), so a subwoofer is needed for real extension below that. Low-frequency harmonic distortion increases substantially at 96dB versus 86dB, though it’s second-order and less audible than it looks on paper. Minimum impedance dips to 2.6 ohms (EPDR as low as 1.2 ohms), so it wants an amplifier comfortable driving 4-ohm loads, ideally 100W or more. At 102dB, compression noticeably eats into midrange, bass, and some treble output. Shipping to the US adds roughly $200 on top of the $935 price. Against the reviewer’s reference Audiofirst Fidelia at a similar price, has slightly less lower-midrange body (about 1dB difference) and a smaller perceived soundstage size.
Full AsciLab C6B review and specifications →
| Bass Extension (-10dB) | 35Hz (measured, Erin's Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 54Hz (measured, Erin's Audio Corner) |
| Dimensions | 15.7"H x 8"W x 10.4"D (398.8 x 203.2 x 264.2 mm) |
| Drivers | 6" Aluminium Ceramic Cone with cast Aluminium Chassis woofer, 1" Aluminium Ceramic Dome tweeter |
| Impedance | 4 ohms nominal, 2.6 ohms minimum (measured, Erin's Audio Corner) |
| Sensitivity | 85.6dB (measured, Erin's Audio Corner) |
| Weight | 18.5 lbs / 8.4 kg each |
| Woofer Cabinet | passive radiator |
- Links
- Reviews, Comparisons and Sound Samples
- Erin’s Audio Corner: STOP Wasting Money on Bad Speakers – AsciLab C6B Review More from Erin’s Audio Corner →
- Erin’s Audio Corner: I Tested 250 Speakers So You Don’t Have To!
- Erin’s Audio Corner Website: AsciLab C6B
- Erin’s Audio Corner Measurements (spinorama.org)
- Reddit Search for AsciLab C6B Review
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