The Buchardt Audio S400 is rated 4.4/5 for sound quality, #30 of 222 Large Size Bookshelf Speakers. See all Passive Home rankings for every top pick.
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Brand: Buchardt
#30 Buchardt Audio S400: €1,800 per pair Discontinued eBay
Newer model: the Buchardt S400 MK3, ranked lower, estimated 4/5, released Mar 2026. See every Buchardt S400 generation.
Pros: A compact bookshelf speaker with impressively deep bass for its size and smooth, broad dispersion, now discontinued but worth buying used. Compact passive design with a 6-inch aluminum woofer, rear passive radiator and waveguided 0.74-inch tweeter positioned below the woofer. Erin measured F3/F10 at 53Hz/38Hz, approximately 86dB/2.83V/1m sensitivity and smooth, broad horizontal directivity. The waveguide controls crossover handoff effectively, the passive radiator avoids port chuffing, and Erin heard no objectionable narrow-band distortion despite excellent extension for the enclosure volume. Measured bass extension of 53Hz (-3dB), with a measured sensitivity of 86dB.
Cons: The impedance reaches 3.7 ohms (Erin), so a genuinely four-ohm-stable separate amplifier is recommended rather than a basic AVR. Low-frequency distortion naturally rises at high output and the compact woofer cannot supply theater-level deep bass; crossing to a subwoofer protects headroom. Erin measured narrow distortion features above 8-9kHz and vertical lobing outside the intended axis. This is the original S400, distinct from the Buchardt S400 MKII already ranked. Discontinued.
| Released | Feb 2019 (7 years ago) |
|---|---|
| Bass Extension (-10dB) | 38Hz (measured, Erin’s Audio Corner) |
| Bass Extension (-3dB) | 53Hz (measured, Erin’s Audio Corner) |
| DIY Kit | No |
| Dimensions | 14.8”H x 7.1”W x 9.6”D (375 x 180 x 245 mm) |
| Drivers | 0.74” waveguided tweeter; 6” aluminum woofer |
| Impedance | 3.7 ohms minimum (measured, Erin’s Audio Corner) |
| Sensitivity | Approximately 86dB/2.83V/1m (measured, Erin’s Audio Corner) |
| Spinorama Preference Score | 5.23 |
| Spinorama Preference Score with Perfect Sub | 7.43 |
| Weight | 16.1 lbs (7.30 kg) each |
| Woofer Cabinet | sealed with rear passive radiator |
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