S400 MK3

Why it is renowned

The S400 has been at the centre of Buchardt's range since its first prototype in 2016, and became one of the most often recommended compact stand-mounts in its class for the scale of sound it drew from a small box.¹² StereoLife covered the MK3 at its launch in 2026, reporting Buchardt's account that it answers what owners and reviewers had asked of the earlier versions: more dynamic authority and more treble detail.¹

The story

The first S400 was the first hi-fi speaker developed with a Klippel Near Field Scanner, which let Buchardt shape its waveguide precisely, and it used passive radiators for its bass; the MK2 followed in 2021.² The MK3 is a complete redesign that keeps only the binding posts.²

Its cabinet holds 18 per cent more air, which allowed a change from passive radiators to a rear bass-reflex port.²¹ The woofer is a 7.5-inch SB Acoustics Satori with a cone of Egyptian papyrus fibre and 65.5 per cent more displacement headroom than the MK2's, and a new 26 mm aluminium dome tweeter sits in a 7.5-inch aluminium waveguide.² The crossover, at 2.2 kHz, uses air-core coils and Cross Cap capacitors from Jantzen Audio, and the cabinet is moisture-proof fibreboard with internal bracing.²