Short answer: the ELAC BS U5 for better sound quality, the Acoustic Energy AE100 Mk2 for the lower price. The ELAC BS U5 ranks #21 of 34 bookshelf speakers at $856. The Acoustic Energy AE100 Mk2 ranks #23 at $500, $356 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. 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.
What the Acoustic Energy AE100 Mk2 offers: Good directivity linearity - on-axis and off-axis response track each other well despite an otherwise uneven overall response, which means the tonal problems can be EQ’d out with reasonably good success. Watch for: High-frequency level runs noticeably too hot regardless of placement - the reviewer tried four different setups (near/far from wall, on-axis, 30° off-axis) at two listening distances and couldn’t get it to sound right at any of them.
Buy the ELAC BS U5 if sound quality matters more than the price. Buy the Acoustic Energy AE100 Mk2 if the price matters more than sound quality.
Specifications Side By Side
| ELAC BS U5 | Acoustic Energy AE100 Mk2 | |
|---|---|---|
| Price | $856 Discontinued | $500 |
| Ranked | #21 of 34 in Medium Size Bookshelf Speakers | #23 of 34 in Medium Size Bookshelf Speakers |
| Drivers | 1" tweeter + 5.25" woofer | 5.25" midwoofer, 1" soft fabric dome tweeter with waveguide |
| Discontinued | Yes | - |
| Weight | 13.2 lbs / 6 kg | 20 lbs each |
| Sensitivity | 85dB | 84dB (measured average, Erin’s Audio Corner) |
| Impedance | 4 ohms nominal (3.4 ohms minimum) | 6 ohms nominal, 4.7 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) | 11.4"H x 6.5"W x 9.8"D (290 x 165 x 250 mm) |
| Woofer Cabinet | ported, rear | ported, rear slot port |
| Crossover Frequency | - | 2.9kHz |
| Bass Extension (-3dB) | - | 63Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-10dB) | - | 42Hz (measured, Erin’s Audio Corner) |
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- ELAC BS U5 vs JBL Stage 2 250B
The Two Speakers In Full
ELAC BS U5: $856 Discontinued
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 →
| 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 | 85dB |
| Weight | 13.2 lbs / 6 kg |
| Woofer Cabinet | ported, rear |
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- Reviews, Comparisons and Sound Samples
- Head-to-Head Comparisons
Acoustic Energy AE100 Mk2: $500 Amazon
Pros: Good directivity linearity - on-axis and off-axis response track each other well despite an otherwise uneven overall response, which means the tonal problems can be EQ’d out with reasonably good success. Wide horizontal radiation, about ±50°. Nicely finished cabinet - the reviewer specifically called out the fit and finish as a genuine positive. Both units of the review pair measured closely matched to each other.
Cons: High-frequency level runs noticeably too hot regardless of placement - the reviewer tried four different setups (near/far from wall, on-axis, 30° off-axis) at two listening distances and couldn’t get it to sound right at any of them. A mid-range dip that the reviewer attributes to internal cabinet resonance rather than intentional baffle-step compensation, reinforced by an internal inspection showing no cross-bracing and a slot port that may itself be resonating when tapped. Small tweeter waveguide magnet suggests limited power handling headroom. At this price and radiation pattern, the reviewer would pick the ELAC DBR62 (more neutral, similar ±60° pattern) or, for less money, the ELAC Debut 2.0 B6.2 over this speaker; the KEF Q150 and SVS Prime Bookshelf are also called out as more linear alternatives nearby in price.
Full Acoustic Energy AE100 Mk2 review and specifications →
| Bass Extension (-10dB) | 42Hz (measured, Erin's Audio Corner) |
|---|---|
| Bass Extension (-3dB) | 63Hz (measured, Erin's Audio Corner) |
| Crossover Frequency | 2.9kHz |
| Dimensions | 11.4"H x 6.5"W x 9.8"D (290 x 165 x 250 mm) |
| Drivers | 5.25" midwoofer, 1" soft fabric dome tweeter with waveguide |
| Impedance | 6 ohms nominal, 4.7 ohms minimum (measured, Erin's Audio Corner) |
| Sensitivity | 84dB (measured average, Erin's Audio Corner) |
| Weight | 20 lbs each |
| Woofer Cabinet | ported, rear slot port |
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