This shows the contour response of S400 (how a speaker spreads the frequencies off.axis). S400 keeps and controls the directivity from 1000 hz and all the way up.

Contour response in 3D


The listener is exposed to: 1. Direct sound, 2. Early Reflections and 3. Sound Power.


On-axis response most speakers get right. But if they have an irregular off-axis response and directivity, the early reflections and sound power might be flawed, especially around the crossover point. S400 has nearly the same frequency response off-axis as on-axis. Meaning that at even extreme angles the sound will be authentic and the reflections bouncing around the room are not distorted. This gives improved imagining precision, larger soundstage, and transparency. It also widens the sweet spot drastically and you will notice that the sound doesn't change character no matter where you are in the room. For many rooms this is very desirable - especially in untreated rooms. Research suggest that the in-room response can be estimated from around 12% Direct sound, 44% Early reflections and 44% Sound Power – S400 will deliver exceptional in-room performance in any room.



The secret to the exceptional controlled directivity is in what we call Constant Directivity Control waveguide. It is designed/simulated with state of the art computation methods. It was tested with a new, very advanced holographic nearfield scanner, mapping the complete acoustic 3d output with 5402 measurements on each of the 5 prototypes we did. The result combined with the tiny 19mm tweeter is spot-on!. A challenge that had to be solved using such a deep waveguide that we ended up with, was the phase-shift between the woofer and the tweeter. This was solved by placing the waveguide under the woofer as well as a very discreet tilt of the cabinet at only two degrees. This aligns the drivers in phase. Because of the high directivity of the waveguide, the edge diffractions from the cabinet is reduced with 90% compared with standard tweeter placements most other speakers use. The sound does not “stick” to the box, but leaves it freely without audible artifacts. This helps even more with imagining and makes the loudspeaker disappear in the soundstage.




Normally we see 25 - 29mm tweeters. Small or large, both have advantage and disadvantages. A large tweeter can work at lower crossover points, but they will suffer with off-axis performance, and you can argue that they don't do as good of a job in the very high frequencies as well. The opposite replies for the smaller tweeters; better off-axis performance and better high frequency performance, but they need to have a higher crossover point. With the help of our very deep waveguide, the 19mm tweeter gets so much acoustic help, that we are able to set the crossover point extraordinary low, 2000hz.  


It’s no secret that the tweeter isn't an over expensive, exotic beryllium dome, no, it’s actually just a standard good textile dome that we customized a bit. The combination with this and the waveguide simply out-performed everything else we tested - including the beryllium.



Normally aluminum is only suitable for pure bass because of its break-up points in the midrange frequencies. However this has been fixed with break-up compensation in the cone. Look closely, and you can actually see the “stripes” in the cone itself. This lets us utilize the full potential of the aluminum without its normal drawbacks! It's a long stroke woofer design with amazing control and power! It's capable of playing extremely deep bass and quite loud as well!



A passive radiator is a way more expensive solution than a bass reflex port. It’s without a doubt the reason we don't see them often. But it's chosen for the following reasons:

+ 30% reduction of cabinet size

+ Amazing bass performance!

+ No port noise

+ No port compression

+ Can be placed very close to a wall (if necessary!)


What is a Passive Radiator?

A passive radiator looks like a normal driver (speaker) from the front, but on the backside, it have had all of its "guts" removed. A passive radiator is a speaker without the magnet, and electronic structure attached to it; it is just the cone, suspension, and frame.

Basically, a passive radiator is a reactionary device as the name suggests. When a driver (such as a subwoofer) is mounted to a sealed speaker box (enclosure), the physical forward/back movement of the speaker affects the internal air pressure of the enclosure. When a passive radiator is mounted to the same speaker box, the internal air pressure fluctuations (caused by the movement of the driving speaker) causes the passive radiator to begin moving forward/back as if it was also a driven speaker. When the passive radiator moves, it creates sound frequencies just as a normal driver does.


Advantages of Passive Radiators

Passive radiators allow woofers to produce deep tones, that otherwise may not have been possible. Depending on the tuning when incorporated, a passive radiator will start to move as the drive woofer begins to produce lower frequencies. By engaging at this point, the passive radiator absorbs energy from the drive woofer thus reducing the drive woofer's motion (we call this dampening). Since the drive woofer is now moving less, there is less risk of damage occurring, due to over excursion (speaker moves so far it breaks). There are two main advantages here:

1.   The motion of the drive woofer is dampened thus flattening the frequency response; this makes for smooth sound reproduction.

2.   Passive radiator systems can have the same sonic output as larger speaker cabinets, but in a much smaller size*.

In a nutshell, when a passive radiator is tuned properly, it can greatly enhance the sonic capabilities of a speaker in regards to low frequency production.



Most companies shrug when it comes to the crossover quality, it's mainly because you don't see it.

In a Buchardt speaker you will only find high-quality components that last for a long time. This means low tolerance, for matching L/R speakers. This also means that the components don’t deteriorate with time. The capacitors used is the metallized film type. They are much more expensive than the electrolytic types but these sound way better and does not dry out or change behavior with age. We don't accept iron core inductors in a 2 way speaker! Only high quality cobber air coils are used for their much lower distortion.


This speaker will work best in room sizes up to 60 sqm.



Operating principle:  2-way Passive radiator system

Tweeter:  1 x 0,74" Custom fine weave soft fabric textile with CDC aluminum waveguide

Mid / woofer:  1 x 6" Aluminum cone with break-up optimization  

Passive Radiator:  1 x 5x8" Long throw passive radiator with very low mass added

Impedance:  4 ohm

Sensitivity:  88 dB

Frequency response:  33 - 40.000 Hz +/- 3db

Crossover Point:  2000hz

Power recommendation:  40 - 200 W

Measurements (h x w x d):  365 x 180 x 240 mm

Weight:  18 kg / set