Review: Buchardt Audio S400

Buchardt Audio's most ambitious - and best - speaker to date

Buchardt Audio S400 plays music excellently, it is extremely decor-friendly - and it plays bass in a way that should not have been possible in a passive speaker of that size.

Our verdict

Buchardt plays deep bass like no other in that size and at that price. And the sound is of high quality.
The S400 costs much more than its predecessors, and it increases the number of competitors. Requires a lot of effect.
  • Functional principle: 2-way with slave bass
  • Treble: 3/4 “textile dome with waveguide
  • Bass / midrange: 6 “aluminum diaphragm, 5×8” slave bass
  • Impedance: 4 ohms
  • Sensitivity: 88 dB
  • Frequency response: 33–40,000 Hz
  • Dimensions / weight: 36.5 x 18.0 x 24.0 cm / 9 kg
  • Colors: black / white / smoked oak, black oak
  • Web:
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Price: £ 1960

Buchardt Audio is a successful Danish entrepreneurial story. Since its inception in 2014, the midget company has gone from success to success with its speakers, which today are exported to many countries. In fact, the success has been so great that we have had to wait a long time to make a couple of the new model available. It has simply been sold out.

The recipe in the Buchardt Audio S400 is the same as in the predecessors S200 and S300: a two-way bookshelf speaker in a nice and unobtrusive design. The speakers are available in white and black, alternatively a smoky oak finish. There is also a signature version in black-stained oak, where the crossover filter must also be of higher quality.

The bass unit is 5″ with aluminum membrane, and the dome tweeter at ¾” is located behind a large waveguide, and is located at the bottom of the cabinet. The back is dominated by a large slave bass, which covers two thirds of the back plate. The terminals are of excellent quality.


The back is dominated by a large passive radiator, which covers two thirds of the back plate. Photo: Buchardt

Global mail order

The Buchardt speakers cannot be tried in traditional stores. Mads Buchardt has instead chosen to focus exclusively on direct sales from his online store. This makes it a little harder to hear them in advance, but the company offers free shipping and a 30-day free return policy – worldwide. The latter is relevant enough as Buchardt exports to about 50 countries.

A speaker of this size invites to be placed on a shelf. According to Buchardt, this is also perfectly fine, as long as the passive unit has some space to work. They still do best on a stand, a little away from the wall. It gives the soundscape a better perspective.

None of Buchard’s speakers are particularly large, but the S400 is actually significantly smaller than its little brother S300, especially in depth. The passive slave bass has made it possible to tune the cabinet to a lower cut-off frequency than a correspondingly large bass reflex speaker. That kind of thing does not normally happen with impunity. If you try to achieve deep bass in a small cabinet, the consequence is usually low sensitivity and imprecise impulse response. In Buchard’s case, however, it works excellently.


A speaker of this size invites to be placed in a bookcase. That, too, according to Buchardt, is perfectly fine. Photo: Buchardt

The Sound Quality

The S400 delivers a forward-leaning soundscape, where the sound comes out properly in front of the speakers and where the stereo perspective reaches far beyond their position. Please note as long as the recording offers sufficient room information. For example, on Roger Water’s Q-sound manipulative album Amused to Death: On Three Wishes, the resounding voice of the bottle spirit returns almost completely to the listening position. It testifies that Buchardt has control over the phase course.

The introduction to One Night in Bangkok from Chess also gives a real concert hall feeling, with good width and height. There is also plenty of feeling of space on the Telarc edition of the Bandit Gallop. And the tiny boxes actually manage to give the timpani credible weight. As if they stretch the 180 W powerful NAD M32 to the limit of what it can handle.

On the bass and vocal test Right Hand Man from the musical Hamilton, there is both a full level right down to the bottom and a completely relaxed nuance of the various male voices. And the bass remains precise, even if the slave diaphragm on the back moves up to one centimeter.

The Buchardt speakers manage to demonstrate the differences in the recordings clearly, which testifies to quality. A large hall sounds large, while an intimate recording is differently dense. And if you put on a bad recording, it is revealed mercilessly. I really like the bloody atmosphere on the album The Tyburn Jig with the London band Ghostfire. Here, too, the mix is ​​incredibly well connected.

More competitors

The first speakers from Buchardt cost the couple six thousand kroner. At that price, they swept everything else off the field. The S400 costs almost three times as much, which increases the number of competitors. Dynaudio Evoke 20 and Bowers & Wilkins 705 S2 are two examples of challengers. The Evoke 20 is hard to beat in atmosphere, and the B&W 705 S2’s carbon tweeter is outstanding. But none of them can catch up with the S400 in the bass area. And they also get challenges when it comes to nuance. That such a small business can deliver something that can compete with the big manufacturers is nothing short of impressive.

However, it is part of the story that Mads Buchardt has not been responsible for everything himself. Design and idea are his, but the calculation and measurement work is outsourced to “friends in the industry”, and the cabinets are built in the East (a working method that is also used by much larger manufacturers). But everything comes to Them in Central Jutland before the finished speakers are sent on to the buyers.


The Buchardt Audio S400 has the qualities that have made the company a success: It plays music excellently, it is extremely decor-friendly – and it plays bass in a way that should not have been possible in a passive speaker of that size. In terms of price, the bow is tightened a little harder than before, but fortunately the quality fully matches the larger investment. If you want a pair of small quality speakers in the mid-price range, the S400 should be on the list.

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