Short answer: both are discontinued, and they are rated the same for sound quality, though neither ranks well in its class. (#118 and #119 of 179 bookshelf speakers). Either one is only an option used, so choose on condition and price. If you want one new, the ELAC Uni-Fi 2.0 UB52 replaces the ELAC BS U5 and is rated 2.4/5 at $799. Both are rated below 3.0/5 among the 179 bookshelf speakers, and the Philharmonic Ceramic Mini, ranked #2 at $900, is a better place to start if sound quality matters.
Why pick the ELAC BS U5: A slim discontinued bookshelf speaker with a coaxial driver for smooth off-axis sound and good listening-height flexibility. The tradeoff: 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.
Why pick the Acoustic Energy AE100 Mk2: A nicely finished discontinued bookshelf speaker with wide dispersion and consistent off-axis sound that responds well to EQ. The catch: 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 or the Acoustic Energy AE100 Mk2, whichever you find used in better condition; both are discontinued. For a new speaker, buy the ELAC Uni-Fi 2.0 UB52, which replaces the ELAC BS U5.
Still deciding? The full Passive Home rankings cover every ranked option.
Measured Differences
- Close enough not to matter: bass extension (63 Hz vs 63 Hz, 3 dB down).
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Specifications Side By Side
| ELAC BS U5 | Acoustic Energy AE100 Mk2 | |
|---|---|---|
| Price | $856 per pair Discontinued | $399 per pair Discontinued |
| Ranked | #118 of 179 in Medium Size Bookshelf Speakers | #119 of 179 in Medium Size Bookshelf Speakers |
| Bass Extension (-3dB) | 63Hz (measured, Audio Science Review) | 63Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-10dB) | 41Hz (derived, log-interpolated between spinorama.org -9dB/-12dB points) | 42Hz (measured, Erin’s Audio Corner) |
| Drivers | 1” tweeter + 5.25” woofer | 5.25” midwoofer, 1” soft fabric dome tweeter with waveguide |
| Weight | 13.2 lbs (6 kg) | 20.1 lbs (9.1 kg) each |
| Sensitivity | 83dB (2.83V/1m, measured, Audio Science Review) | 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 |
| Spinorama Preference Score | 4.71 (spinorama.org) | 4.96 |
| Spinorama Preference Score with Perfect Sub | 6.79 (spinorama.org) | 7.18 |
| DIY Kit | No | No |
| Crossover Frequency | - | 2.9kHz |
Where the Ratings Come From
- ELAC BS U5: Spinorama.org measurements and reviews by Audio Science Review.
- Acoustic Energy AE100 Mk2: Spinorama.org measurements and reviews by Erin’s Audio Corner.
This comparison is generated from the ratings, specifications and measurements on each product’s own page, and it updates when that data changes. How we rank explains how each rating is decided.
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