Short answer: the AsciLab C6B is the proven choice, measured and ranked among bookshelf speakers, while the newer SVS Ultra Evolution Bookshelf has no independent measurements yet and can only be compared on specs.
The case for the SVS Ultra Evolution Bookshelf: Two-way rear-ported standmount with a 6.5” composite glass fiber woofer and a 1” diamond-coated aluminium dome tweeter in a time-aligned cabinet.
On the AsciLab C6B side: 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.
Price: the SVS Ultra Evolution Bookshelf lists at $1,199.98 and the AsciLab C6B at $1,145.
Buy the AsciLab C6B if you want a speaker whose sound quality has been measured and ranked.
Buy the SVS Ultra Evolution Bookshelf if you prefer its design or features, and you can wait for measurements to confirm how it sounds.
Looking for alternatives? See the complete Passive Home rankings.
Specifications Side By Side
| SVS Ultra Evolution Bookshelf | AsciLab C6B | |
|---|---|---|
| Price | $1,199.98 per pair | $1145 per pair |
| Ranked | - | #6 of 131 in Large Size Bookshelf Speakers |
| Drivers | 6.5” composite glass fiber cone woofer, 1” diamond-coated aluminum dome tweeter | 6” Aluminium Ceramic Cone with cast Aluminium Chassis woofer, 1” Aluminium Ceramic Dome tweeter |
| Frequency Response | 40Hz-40kHz ±3dB (manufacturer specified) | - |
| Sensitivity | 87dB (2.83V/1m, manufacturer specified) | 85.6dB (measured, Erin’s Audio Corner) |
| Impedance | 6 ohms nominal (manufacturer specified) | 4 ohms nominal, 2.6 ohms minimum (measured, Erin’s Audio Corner) |
| Woofer Cabinet | ported, rear | passive radiator |
| Dimensions | 378H x 220W x 286D mm | 15.7”H x 8”W x 10.4”D (398.8 x 203.2 x 264.2 mm) |
| Weight | 8.6 kg each | 18.5 lbs (8.4 kg) each |
| Cabinet Color | piano gloss black, piano gloss white, black oak | - |
| Country | United States | - |
| Bass Extension (-10dB) | - | 35Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | - | 54Hz (measured, Erin’s Audio Corner) |
| Spinorama Preference Score | - | 6.33 |
| Spinorama Preference Score with Perfect Sub | - | 8.28 |
| DIY Kit | - | No |
Prices on this page were last checked September 29, 2026 at 3:43 PM 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
SVS Ultra Evolution Bookshelf: $1,199.98 per pair SVS eBay
Older model: the SVS Ultra Bookshelf (rated 3.9/5).
Pros: Two-way rear-ported standmount with a 6.5” composite glass fiber woofer and a 1” diamond-coated aluminium dome tweeter in a time-aligned cabinet. SVS rates it at 40Hz to 40kHz (±3dB), deep bass extension for a bookshelf, with 87dB sensitivity and a 6 ohm nominal load.
Cons: Measured by Stereophile and Audioholics, but not in the Spinorama format used for this ranking, so its tonal balance and directivity can’t yet be compared directly with ranked speakers. A rear port needs some space from the wall.
Full SVS Ultra Evolution Bookshelf review and specifications →
| Cabinet Color | piano gloss black, piano gloss white, black oak |
|---|---|
| Country | United States |
| Dimensions | 378H x 220W x 286D mm |
| Drivers | 6.5” composite glass fiber cone woofer, 1” diamond-coated aluminum dome tweeter |
| Frequency Response | 40Hz-40kHz ±3dB (manufacturer specified) |
| Impedance | 6 ohms nominal (manufacturer specified) |
| Sensitivity | 87dB (2.83V/1m, manufacturer specified) |
| Weight | 8.6 kg each |
| Woofer Cabinet | ported, rear |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
AsciLab C6B: $1145 per pair 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 $1145 shipped to the US, the reviewer calls it the best-value bookshelf speaker he’s tested, rivaling speakers 2-5x the price. Measured bass extension of 54Hz (-3dB), with a measured sensitivity of 85.6dB.
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 AsciLab’s list 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) |
| DIY Kit | No |
| 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) |
| Spinorama Preference Score | 6.33 |
| Spinorama Preference Score with Perfect Sub | 8.28 |
| Weight | 18.5 lbs (8.4 kg) each |
| Woofer Cabinet | passive radiator |
- Links
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons