Buchardt Audio S400 MK3 - Bigger and More Powerful Than Before

Danish company Buchardt Audio has released the third version of its most well-known bookshelf loudspeaker, the S400 MK3. The updated model features a larger cabinet, new drivers, and a redesigned crossover, while also undergoing significant structural changes compared with previous versions. Although Buchardt Audio cannot boast a century-long history like some other Scandinavian manufacturers, the brand has built a solid reputation in recent years. This was made possible by a successful concept: relatively compact loudspeakers capable of delivering a bigger and fuller sound than their size would suggest. It was precisely this philosophy that made the original S400 so well known, followed by the S400 MKII with an updated crossover and higher-quality internal components, and later the S400 MKII Signature with additional tuning refinements. Now, in 2026, the company takes the next step and brings the platform to a new level with the release of the S400 MK3.

According to Buchardt Audio, this is not a minor upgrade but a deep redesign of the entire construction. The new model retains the overall sonic character for which the S400 series has been valued – a natural, balanced, and musical presentation – yet the system has been almost completely rethought from a technical perspective. The manufacturer even emphasizes that, in essence, only the speaker terminals remain from the previous generation.

One of the key changes is the enlarged cabinet. Internal volume has increased by around 18%, giving the engineers more freedom to improve bass extension and raise the system’s overall dynamic potential. At the same time, the company notes that the speaker has retained the recognizable restrained aesthetic and neat proportions that have made the S400 series so easy to identify.

High frequencies in the S400 MK3 are handled by a new 26 mm aluminum dome tweeter working in combination with a revised waveguide. The developers did not aim to make the treble brighter or more aggressive – on the contrary, the focus was placed on greater refinement, better detail, and subjectively higher resolution. According to Buchardt, the new tweeter is intended to provide more precise high-frequency dispersion and a more seamless blend with the main driver, while preserving the brand’s characteristic smoothness and long-term listening comfort without sounding fatiguing.

Midrange and bass are reproduced by a 7.5-inch SB Acoustics driver featuring a paper cone made using the company’s proprietary Satori PAPYRUS technology. Compared with the driver used in the S400 MKII, the new unit offers 65.5% greater linear excursion capability, meaning it can move a significantly larger volume of air. In practice, this should deliver freer dynamics, weightier and more confident bass, and a more tangible physical presentation, which is especially important for bookshelf speakers of this size. Combined with the enlarged cabinet, this reportedly gives the speaker deeper low-frequency extension and a more expansive sound.

Another important change concerns the acoustic loading. Whereas previous S400 versions used a passive radiator, the S400 MK3 adopts a rear-firing port and a classic bass reflex design. This approach is said to provide tight, deep, and energetic bass while making full use of the advantages offered by the larger cabinet and the long-throw woofer. As with any bass reflex system, port noise is theoretically possible under very specific operating conditions, although during normal listening it will most likely remain virtually inaudible. As for placement, the model still offers a degree of flexibility, although the manufacturer recommends leaving at least 5 cm between the rear port and the wall to allow proper airflow and correct bass performance.

In developing the crossover for the S400 MK3, Buchardt Audio once again collaborated with Jantzen Audio. The updated network uses high-grade components throughout, although the overall topology has been simplified somewhat compared with the solution used in the S400 MKII. At its core are first-order filters, a choice often associated with better phase coherence and a more natural transition between drivers. Despite the simpler structure, Buchardt emphasizes that component quality and tuning precision remain priorities, because tonal balance and musical cohesion have always been an essential part of the S400 character.

The new Buchardt Audio S400 MK3 is already available for pre-order through the manufacturer’s official website. Deliveries are expected to begin by the end of summer 2026. Recommended pricing is $2,400 USD per pair in black or white finishes, and $2,574 USD for the version finished in natural veneer.