Them, Denmark | 2026 – A new chapter for one of our most important speakers.
The S400 MK3 is a complete redesign with a larger cabinet, new drivers and improved dynamics – while keeping the balanced and natural sound the S400 series is known for.
The S400 has been a cornerstone of our product lineup since its first prototype in 2016. It was also the first HiFi speaker developed using the Klippel Near Field Scanner (NFS), which at the time represented the cutting edge of acoustic measurement technology. This allowed us to develop a waveguide with unprecedented precision – a design that remains fundamental to many of our speakers today.
Combined with its compact cabinet and the innovative use of passive radiators, the original S400 quickly earned worldwide recognition as a small speaker capable of delivering unexpectedly powerful sound.
Over the years, the S400 became one of the most frequently recommended stand-mount speakers in the €2,000 – €3,000 class. When the S400 MK2 was introduced in 2021, it further refined the concept with an improved crossover and exceptionally high-quality components, strengthening its reputation for performance far beyond its price. But in loudspeaker design, perfection does not exist. Every product is a balance of priorities, and we continuously listen to feedback from both customers and reviewers.
One insight became clear: while the S400 was designed to deliver maximum performance from a very compact enclosure, it was often compared to competitors that were significantly larger in size. Another consistent request was even greater treble resolution and increased dynamic authority. The S400 MK3 is our answer to that feedback.
This new generation is a complete redesign, reusing only a single component from its predecessor – the binding posts.
Larger Cabinet, Greater Capability
The first noticeable change in the S400 MK3 is its size. The cabinet volume has increased by 18%, allowing us to push the performance envelope further while maintaining the elegant proportions of the original design.
At the heart of the new system is a 7.5-inch woofer, specifically the SB Acoustics Satori PAPYRUS™ paper cone driver providing a wopping 65.5% greater displacement headroom compared to the S400 MK2.
Rather than developing a proprietary driver hidden behind branding, we chose one of the finest commercially available drivers in the world. This decision reflects our philosophy of transparency and value: we want customers to clearly see the level of engineering and component quality that goes into our speakers.
Drivers of this caliber are typically found in high-end DIY builds or far more expensive speakers. Seeing one in a finished branded speaker at this price point does not exist today.
The S400 have been completely redesigned!
| TECHNICAL SPECIFICATIONS | – |
|---|---|
| Operating principle | 2-way passive bass reflex system |
| Tweeter | 1 x 1″ waveguided custom aluminum dome with neodymium matrix motor. |
| Mid / woofer | 1 x 7.5″ SATORI EGYPTIAN PAPYRUS™ papercone with neodymium motor |
| Cabinet | 15mm fiberboard HMR.E2 Moisture-proof with internal bracing. Either painted or real wood veneered. |
| Impedance | 4 ohms |
| Sensitivity | 88 dB |
| Frequency response | 33 – 20.000 Hz +/- 3dB (in-room) |
| Crossover | 2400hz woofer (1st Order – 6dB/oct) tweeter (Quasi-1st Order) |
| Power recommendation | From 30 watts. Depends on use case, please ask us for recommendations. |
| Measurements (h x w x d) | 392 x 198 x 280 mm (15.4” x 7.8” x 11”) |
| Weight | 8.5 kg each / 18.7 kg shipped |
| Speaker grilles | 4 x 7.5″ Included black acoustical optimized fabric grilles |
| Warranty | 5 years (10 years locked to first buyer’s name) |
The new Woofer
The larger 7.5″ woofer and increased excursion capability significantly raise the dynamic potential of the S400 MK3. Compared to the MK2, the new design offers 65.5% greater displacement headroom, allowing the speaker to play louder, cleaner, and with greater authority. This translates directly into a stronger sense of impact and physical presence, particularly in bass and mid-bass reproduction.
The powerful neodymium motor system also provides a slight increase in sensitivity, making the MK3 easier to drive and more compatible with a wider range of amplifiers.
Some of the design features of this new woofer are :
– Vented aerodynamic cast aluminium chassis for optimum strength and low compression
– Proprietary cone material with EGYPTIAN PAPYRUS™ fibres made in-house
– Soft low damping rubber surround for optimum transient response
– Advanced BIMAX spider for improved linearity
– Powerful optimized low distortion neodymium motor system
– Non-conducting fibre glass voice coil former for minimum damping
– Extended copper sleeve on pole piece for low inductance and reduced distortion
– CCAW voice coil for reduced moving mass
– Long life silver lead wires attached 180° apart for improved stability
– Vented pole piece for reduced compression
– Low piston to chassis diameter ratio
– Gasket and bolt hole protrusions for reduced coupling to speaker cabinet
A new Generation Tweeter
If there was one area where the S400 received the most feedback over the years, it was the tweeter.
While the previous generation tweeter measured exceptionally well, some listeners desired greater perceived clarity and resolution.
The MK3 introduces a completely new tweeter designed specifically for this system.
Its 26 mm ultra-light aluminum dome is powered by a high-efficiency matrix neodymium motor with copper in the magnet system for low impedance. An optimized back chamber that allows for a low resonance point that enables the use of a quasi-first-order tweeter crossover while keeping the crossover frequency at only 2400hz. The tweeter is bonded directly into the newly developed 7.5-inch aluminum waveguide.
At first glance, the use of an aluminum dome may seem like a departure from the soft-dome heritage of earlier S400 models. However, careful engineering ensures that the typical aluminum breakup modes are pushed far beyond the audible band – well above 20 kHz.
This allows the tweeter to deliver the speed and transient precision of a hard dome while maintaining the smooth, fatigue-free presentation that S400 owners have always appreciated. The goal was not to create a brighter speaker, but a more refined one.
Crossover without Compromise
High-performance drivers deserve equally high-quality parts behind them. The S400 MK3 crossover continues our collaboration with Jantzen Audio, utilizing carefully selected components throughout the signal path.
Key elements include:
– Air-core inductors up to 1.6 mm (14 AWG) made with high-purity copper and baked bonding lacquer for extremely low distortion.
– Jantzen Cross Cap polypropylene capacitors, known for their neutral sonic character and minimal distortion.
– Superes wire-wound resistors, selected for their reliability and audio-grade performance.
While the crossover topology is somewhat simpler than the MK2 design, the commitment to component quality remains unchanged.
Our philosophy is simple: we don’t compromise on part quality, even if they are hidden inside the speaker.
From passive Radiatior to Bass Reflex
With the increased cabinet volume, the S400 MK3 can transition from the passive radiator design of earlier generations to a bass reflex system. This allows us to maintain the deep and controlled bass performance that the S400 is known for while simplifying the acoustic system and spending the savings elsewhere. The result is bass that remains tight, extended, and powerful with the only downside of having minimal port noise audible under very specific conditions. The speakers does still work well close to walls, just be sure to leave a minimum of 5cm space for the port to breathe.
Sound Signature
The S400 MK3 is designed around a balanced and natural presentation.
It is neither overly warm nor overly bright – neither forward nor laid back. Instead, it aims for a carefully judged middle ground that allows music to sound engaging across a wide range of recordings and genres.
The paper-cone woofer contributes natural warmth and body to the midrange while maintaining excellent clarity and articulation. Compared with the MK2, the MK3 offers noticeably improved midrange resolution and openness. The bass has the same linearity as the MK2, but the output, impact and physicality of the bass have improved in the MK3 significantly due to the increased cone size and stroke distance.
The new tweeter introduces a greater sense of detail and refinement, particularly in transient information such as cymbal strikes and subtle spatial cues. Hard-dome tweeters excel at presenting the leading edge of transients with exceptional precision, and this quality adds realism without introducing harshness.
Our goal was to enhance detail while preserving the effortless listenability that defined earlier S400 generations.
Soundstage and Imaging
One of the defining strengths of the S400 platform has always been its soundstage performance. The waveguide provides precise directivity control, ensuring smooth integration between the tweeter and woofer while minimizing edge diffraction. This helps the speaker interact more naturally with the listening room. The result is a presentation where the speakers seem to disappear, leaving behind a wide, holographic soundstage with precise image placement.
Controlled Directivity and why it´s important
So the good news is that most present-day loudspeakers tend to sound pretty good on-axis. What’s also true is that there are still many loudspeakers that perform rather poorly as soon as you move off-axis. Since most research results suggest that what we hear in-room is estimated to be around 12% Direct Sound (from your speakers), 44% Early Reflections (from your room), and 44% Sound Power (how the sound loads your room), we strive to create solutions that’ll deliver predictable, consistent, and excellent results both on and off axis – regardless of the living space!
Note how the S400 possesses nearly the same frequency response on-axis as it does in the off-axis.
What this translates to is a non-distorted, evenly distributed in-room frequency response that allows the S400’s to sound balanced even at extreme angles, which in turn allows the enthusiast to enjoy sundry benefits like improved imaging, a bigger soundstage, and better transparency. This excellent off-axis response will also result in a drastically widened ‘sweet spot’ and most importantly, a character that will remain steadfast even as you move around your home as the music plays.
We’ve found that this trait is best suitable for most people’s rooms and lifestyles. Especially those with untreated rooms. The bottom line? The S400 is capable of delivering exceptional in-room performance in any room.
