Short answer: the Ascend Sierra 1 v2 for better sound quality, the ELAC BS U5 for the lower price. The Ascend Sierra 1 v2 ranks #3 of 71 bookshelf speakers at $1000. The ELAC BS U5 ranks #44 at $856, $144 cheaper.
What the ELAC BS U5 offers: This slim three-way coaxial design (an Andrew Jones creation) shows a fairly even on-axis response up to 3kHz, with off-axis behavior notably smoother than the on-axis curve. Predicted in-room response looks like it should give good tonality. Vertical directivity is better than average, a benefit of the coaxial layout. Watch for: Distortion is very high right at both crossover points - around 270Hz (mid-range) and 2700Hz (tweeter) - at both 86dB and 96dB SPL/1m, exceeding 3% at the mid-range crossover. Minimum impedance dips to 3.4 ohms with a possible resonance around 500Hz visible in the impedance/phase curve.
What the Ascend Sierra 1 v2 offers: Formaldehyde-free layered bamboo ply cabinet with a 1” dome tweeter over a 5.25” midwoofer, mated by a 4th-order acoustic crossover rather than a stock textbook design. In-room response is extremely linear - the reviewer called it “textbook” - a clear step up from the earlier V1, which had boxiness around 700Hz-1kHz and sibilance around 4-6kHz. Preference score of 8.4 with a subwoofer (6.8 without), which the reviewer calls topnotch. Wide, even horizontal radiation of about ±70° up to 6kHz. Better vertical directivity than its tweeter-to-woofer spacing would suggest, thanks to the steep 4th-order crossover slopes. No mechanical noise, port chuffing, or woofer bottoming even driven to 96dB/1m. In a three-way comparison against the Dynaudio Emit 20 and a Revel bookshelf model (all around $1,000/pair), measured as the most linear of the three and was the reviewer’s personal pick over both, despite the Dynaudio’s deeper bass and higher output capability. Independent ASR Klippel measurements corroborate Erin’s findings: superb off-axis response with only slight on-axis variations, and an in-room response the reviewer called “incredibly smooth and accurate - amazing for a non-DSP speaker.” Distortion above 200Hz at 86dB/1m is very low for the class. Watch for: F3 of 55Hz and F10 of 39Hz mean in-room extension tops out in the mid-40s Hz; the reviewer still recommends a subwoofer for full-range material. Diffraction dips appear around 3kHz and 5-6kHz, and the 1” dome tweeter starts beaming above roughly 6.7kHz, narrowing the soundstage radiation in the top octave - a straightforward consequence of dome size rather than a design flaw. At 96dB/1m the 5.25” midwoofer shows increased distortion in the midrange, likely tied to motor topology; high-passing to a subwoofer around 80Hz largely clears it up. Moderate sensitivity (~81-82dB average) with a 7-ohm minimum impedance. ASR’s power-sweep testing found response holds steady up to 96dB SPL/1m, but pushing to 102dB causes midbass below 400Hz to sag with distortion “through the roof” - a harder output ceiling than the 96dB tests alone suggest. Vertical directivity also narrows above about 1kHz, so the reviewer recommends staying at tweeter-axis height for best results.
Buy the ELAC BS U5 if the price matters more than sound quality. Buy the Ascend Sierra 1 v2 if sound quality matters more than the price.
Specifications Side By Side
| ELAC BS U5 | Ascend Sierra 1 v2 | |
|---|---|---|
| Price | $856 Discontinued | $1000 |
| Ranked | #44 of 71 in Medium Size Bookshelf Speakers | #3 of 71 in Medium Size Bookshelf Speakers |
| Bass Extension (-3dB) | 78Hz (measured, Audio Science Review) | 55Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-10dB) | 60Hz (measured, Audio Science Review) | 39Hz (measured, Erin’s Audio Corner) |
| Drivers | 1" tweeter + 5.25" woofer | 5.25" proprietary mineral-filled polypropylene cone with cast aluminum frame woofer, 26mm aluminum/magnesium alloy dome tweeter with titanium former (SEAS Titan) |
| Discontinued | Yes | - |
| Weight | 13.2 lbs / 6 kg | 18.5 lbs / 8.4 kg each |
| Sensitivity | 83dB (2.83V/1m, measured, Audio Science Review) | 81.5dB (measured, Erin’s Audio Corner) |
| Impedance | 4 ohms nominal (3.4 ohms minimum) | 8 ohms nominal, 7 ohms minimum (measured, Erin’s Audio Corner) |
| Dimensions | 13.4"H x 7"W x 11.5"D (339.1 x 178.0 x 293.1 mm) | 14.2"H x 7.5"W x 10.5"D (361.9 x 190.5 x 266.7 mm) |
| Woofer Cabinet | ported, rear | ported |
Related Speaker Comparisons
More useful head-to-heads from the same speaker class:
- JBL Stage 2 250B vs Dynaudio X14
- KEF LS50 Meta vs Boston Acoustics A25
- Dynaudio Emit M10 vs JBL L52 Classic
- Ascend Sierra 1 v2 vs Philharmonic Ceramic Mini
- Dynaudio Emit M10 vs Ascend Sierra 1 v2
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The Two Speakers In Full
ELAC BS U5: $856 Discontinued eBay
Pros: This slim three-way coaxial design (an Andrew Jones creation) shows a fairly even on-axis response up to 3kHz, with off-axis behavior notably smoother than the on-axis curve. Predicted in-room response looks like it should give good tonality. Vertical directivity is better than average, a benefit of the coaxial layout.
Cons: Distortion is very high right at both crossover points - around 270Hz (mid-range) and 2700Hz (tweeter) - at both 86dB and 96dB SPL/1m, exceeding 3% at the mid-range crossover. Minimum impedance dips to 3.4 ohms with a possible resonance around 500Hz visible in the impedance/phase curve. Discontinued.
Full ELAC BS U5 review and specifications →
| Bass Extension (-10dB) | 60Hz (measured, Audio Science Review) |
|---|---|
| Bass Extension (-3dB) | 78Hz (measured, Audio Science Review) |
| Dimensions | 13.4"H x 7"W x 11.5"D (339.1 x 178.0 x 293.1 mm) |
| Discontinued | Yes |
| Drivers | 1" tweeter + 5.25" woofer |
| Impedance | 4 ohms nominal (3.4 ohms minimum) |
| Sensitivity | 83dB (2.83V/1m, measured, Audio Science Review) |
| Weight | 13.2 lbs / 6 kg |
| Woofer Cabinet | ported, rear |
- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
- ELAC BS U5 vs JBL Stage 2 250B
- ELAC BS U5 vs Dynaudio Emit M10
- ELAC BS U5 vs Acoustic Energy AE100 Mk2
- ELAC BS U5 vs Dynaudio X14
- ELAC BS U5 vs Paradigm Monitor SE Atom
- ELAC BS U5 vs Pioneer SP-BS22-LR (Philharmonic AAM Mod)
- ELAC BS U5 vs JBL L52 Classic
- ELAC BS U5 vs Sony SS-CS5 M2
- See all 26 comparisons
Ascend Sierra 1 v2: $1000 Ascendacoustics eBay
Pros: Formaldehyde-free layered bamboo ply cabinet with a 1” dome tweeter over a 5.25” midwoofer, mated by a 4th-order acoustic crossover rather than a stock textbook design. In-room response is extremely linear - the reviewer called it “textbook” - a clear step up from the earlier V1, which had boxiness around 700Hz-1kHz and sibilance around 4-6kHz. Preference score of 8.4 with a subwoofer (6.8 without), which the reviewer calls topnotch. Wide, even horizontal radiation of about ±70° up to 6kHz. Better vertical directivity than its tweeter-to-woofer spacing would suggest, thanks to the steep 4th-order crossover slopes. No mechanical noise, port chuffing, or woofer bottoming even driven to 96dB/1m. In a three-way comparison against the Dynaudio Emit 20 and a Revel bookshelf model (all around $1,000/pair), measured as the most linear of the three and was the reviewer’s personal pick over both, despite the Dynaudio’s deeper bass and higher output capability. Independent ASR Klippel measurements corroborate Erin’s findings: superb off-axis response with only slight on-axis variations, and an in-room response the reviewer called “incredibly smooth and accurate - amazing for a non-DSP speaker.” Distortion above 200Hz at 86dB/1m is very low for the class.
Cons: F3 of 55Hz and F10 of 39Hz mean in-room extension tops out in the mid-40s Hz; the reviewer still recommends a subwoofer for full-range material. Diffraction dips appear around 3kHz and 5-6kHz, and the 1” dome tweeter starts beaming above roughly 6.7kHz, narrowing the soundstage radiation in the top octave - a straightforward consequence of dome size rather than a design flaw. At 96dB/1m the 5.25” midwoofer shows increased distortion in the midrange, likely tied to motor topology; high-passing to a subwoofer around 80Hz largely clears it up. Moderate sensitivity (~81-82dB average) with a 7-ohm minimum impedance. ASR’s power-sweep testing found response holds steady up to 96dB SPL/1m, but pushing to 102dB causes midbass below 400Hz to sag with distortion “through the roof” - a harder output ceiling than the 96dB tests alone suggest. Vertical directivity also narrows above about 1kHz, so the reviewer recommends staying at tweeter-axis height for best results.
Full Ascend Sierra 1 v2 review and specifications →
| Bass Extension (-10dB) | 39Hz (measured, Erin's Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 55Hz (measured, Erin's Audio Corner) |
| Dimensions | 14.2"H x 7.5"W x 10.5"D (361.9 x 190.5 x 266.7 mm) |
| Drivers | 5.25" proprietary mineral-filled polypropylene cone with cast aluminum frame woofer, 26mm aluminum/magnesium alloy dome tweeter with titanium former (SEAS Titan) |
| Impedance | 8 ohms nominal, 7 ohms minimum (measured, Erin's Audio Corner) |
| Sensitivity | 81.5dB (measured, Erin's Audio Corner) |
| Weight | 18.5 lbs / 8.4 kg each |
| Woofer Cabinet | ported |
- Links
- Reviews, Comparisons and Sound Samples
- Erin’s Audio Corner: NEW! Ascend Acoustics Sierra-1 V2 Review More from Erin’s Audio Corner →
- Erin’s Audio Corner Website Ascend Sierra 1 v2
- Audio Science Review Ascend Sierra 1 v2 More from Audio Science Review →
- Erin’s Audio Corner: 5 AWESOME SPEAKERS Under $1000 You Won’t Regret
- Erin’s Audio Corner: I Tested 250 Speakers So You Don’t Have To!
- Erin’s Audio Corner: My Top Picks of 2023: Must-Haves Under $3000
- Manufacturer Measurements (spinorama.org)
- Reddit Search for Ascend Sierra 1 v2 Review
- Head-to-Head Comparisons
- Ascend Sierra 1 v2 vs KEF LS50 Meta
- Ascend Sierra 1 v2 vs Philharmonic Ceramic Mini
- Ascend Sierra 1 v2 vs Audio First Fidelia
- Ascend Sierra 1 v2 vs Arendal 1961 Monitor
- Ascend Sierra 1 v2 vs Moondrop M4P MTM
- Ascend Sierra 1 v2 vs Emotiva B1+
- Ascend Sierra 1 v2 vs Klipsch RP-500M II
- Ascend Sierra 1 v2 vs Wharfedale Super Denton
- See all 24 comparisons