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Floor Standing Loudspeakers

Price (in Poland): 24 000 zł

Manufacturer: ERYK S. CONCEPT

ul. Juliusza Kadena-Bandrowskiego 9/33
01-494 Warszawa | Polska


Country of origin: Poland

Manufacturer's website: ERYK S. CONCEPT

Text: Wojciech Pacuła
Pictures: Wojciech Pacuła | Eryk S. Concept
Translation: Krzysztof Kalinkowski

Report published:
∙ in Polish on Dec 1st 2011, No. 92
∙ in English on Jan 3th 2012, No.92

Usually in this place I tell you about the philosophy of the company, product, or the history of the brand preparing for the listening part. But because Mr. Eryk Smólski, the owner of Eryk S. Concept has interesting things to say, so I decided to give word to him:

“Ketsus Special is the newest version of the loudspeakers Ketsus, tested some time ago in “High Fidelity” in the version Superb, prepared thinking about two of the most difficult criteria (taking into account keeping the same size and shape, women love it).
It was about:
- Filling salons of about 50m2 with sound
- Be powered by SE/SET tube amplifiers, where we rarely have more than 10W power.
To achieve this, while keeping current power and impedance 4Ω 150/200W I succeeded in raising the effectiveness by 3dB to 91dB. It was a real challenge to me, because I needed to keep the frequency response, also because side woofers, despite the theory of “omnidirectional bass” have less pressure!

An additional thing was the flattening of the frequency response and a guarantee, that even with modern harsh/dry/too quick solid state amplifiers the sound will be balanced/musical.
As an effect the cabinet remained without major changes (except for the hidden woofers), the dimensions were slightly modified: 14x40.5x101cm (without spikes), the weight was increased to 30kg/piece. The thickness of the cabinet walls: 20/30/40mm. The finish is piano varnish white pearl (not auto varnish!), and the back and bottom panels are from ebony. The setup of damping in the low frequency chamber is changed, but the materials remained the same: sheep wool, key sponge, bitumen mattes and felt.

The decisive changes are: hiding of the woofers (suggestions of clients and a better visual effect). I also decided to remove the so called SuperTweeter Connector placed on the back, because it caused confusion with clients or was not used at all. I designed the woofers from scratch as well as the fullrange speakers and slightly modified the supertweeter. The cross-over frequency is at 200Hz and 14kHz, and the latter is done by an untypical adding of the supertweeter, because the fullrange reaches 20kHz with some decline. This is a very different 2.5-way system, based on double drivers (this is to fulfill the durability requirement: 2 times lower temperature and power load vs lower distortion).
In addition the woofers have, compared to the previous version, increased throw. Compression of the bass was lowered. On the back we have three bass-reflex tunnels – in this case even at high amplitudes of the woofers the ports do not get adjoined (what would result a setting of a leaky closed cabinet, and thus in significant distortion). The woofers have 100% carbon diaphragms and a very advanced motor (among other things built in circuits correcting the magnetic field and improved cooling).
The fullrange drivers have cellulose diaphragms with special correctors – the whole setup is new, only the external dimensions remained the same. Of course we also have a new cross-over, made from three sections. I used in it (based on listening tests) PIO capacitors for the supertweeter, foil capacitors, bipolar with smooth foil and metalized resistors 1%. The coils in the woofer section have low internal resistance in the range of 0.1Ω. With this construction the filters have especially profiled slopes.
With all that I did not forget about phase. This is one of the few constructions, where I could successfully get rid of any traps and corrective circuits, which help with one thing, but degrade music: attack, details, small three-dimensionality elements, etc. The loudspeaker works well with amplifiers with a damping factor of around 20.
KETSUS Special are factory tuned neutral (electronics, classics, rock, etc, the room medium damped), but at extra price the client can get fine tuning at home, because due to the used solutions the edges of the sound spectrum can be modified in some extent. Please remember, that the final effect is a combination of: the room, 60% of success, accompanying electronics + preferences regarding musical genres and the character of the sound).”

To date we tested:

  • Krakow Sonic Society Nuvo w Krakowie, reportage HERE
  • Stand mount loudspeakers Eryk S. Concept NUVO, test HERE
  • Floor standing loudspeakers Eryk S. Concept KETSU, test HERE
  • Floor standing loudspeakers Eryk S. Concept KETSUS SUPERB, test HERE


Recordings used for the listening session:

  • Audiofeels, UnFinished, Mystic Production, MYSTCD 198, CD (2011).
  • Depeche Mode, Sounds Of The Universe, Mute/EMI Music Japan, TOCP-66878, CD+DVD (2009).
  • Eva Cassidy, Songbird, Blix Street Records/JVC, VICJ-010-0045, XRCD24 (2010).
  • Glen Gould, Bach: The Art Of The Fugue, Sony Music/Sony Classical, SMK 52 595, The Glen Gould Edition, SBM CD (1997).
  • Jean Michel Jarre, Magnetic Fields, Epic/Sony Music, 488138 2, CD (1997).
  • Jeff Buckley, Grace+EP, Sony Music Japan, SICP-2245-7, mini LP, 3 x CD (2009).
  • Marek Biliński, Mały Książę, Bi.Ma, BiCD-09, CD (2010).
  • Marilyn Moore, Moody Marilyn Moore, Bethlehem/JVC, VICJ-61467, mini LP, K2HD CD (2007).
  • Miles Davis, Seven Steps To Heaven, Columbia/Sony Music/Analogue Productions, CAPJ-8851, SACD/CD (2010).
  • Nat “King” Cole, Love is the Thing, Capitol/Analogue Productions, CAPP 824 SA, SACD/CD (2010).
  • Pink Floyd, Wish You Were Here, Experience Edition, EMI Music Japan, TOCP-71169-10, 2 x CD (2011).
  • Radiohead, The King of Limbs, Ticker Tape Ltd., TICK-001CDJ, Blu-spec CD (2011).
  • The Doors, The Doors, Elektra/Warner Music Japan, WPCR-12716, mini LP, CD (2007).

Japanese versions of the discs are available on CD Japan.

Although we see a classic three-way loudspeaker, maybe a bit beefed-up, with somewhat different solutions than usual, but we hear something different. This is not a “different” sound, this is not it – similar as the looks suggest a classical loudspeaker, the sound at first glance suggest a classic construction – there is treble, there is bass, and stage and visualization of the virtual sources – with one word everything about what we talk describing normal loudspeakers.
But we know, that this is not a classic loudspeaker, yes? So I do not need to use any rhetorical figure to get to the point: the sound of the Ketsus Special we perceive differently than the sound of standard loudspeakers. Caution: I do not say better or worse, I just say DIFFERENT.

Those are constructions, where some elements clash together in different configurations than usual, placed and valued differently and due to that not easy to present in a synthetic way. They have a big sound. Those are not “point-like” loudspeakers, projecting a precise, but limited to a small area, sound. This is extended to the top and to the sides, also with monophonic recordings. With discs, such as Moody Marilyn Moore we get a big central picture, without suggesting stereophony (because this is a mono recording), but big and wide – and in effect a very natural one.

Also the instruments and effects in stereophonic recordings have similarly big size – regardless if it will be Welcome To The Machine Pink Floyd from the newest re-master Wish You Were Here, or Sounds of the Universe Depeche Mode. Especially in this first case, with the pulsating, synthetic bass, hitting one time in one channel, another time in the second one, it can be heard, that the loudspeakers can create a vast perspective, wide, without any holes, expansive.
This is mostly depending on the placement of the loudspeakers, meaning if we place the woofers to the inside or to the outside. This is a quite significant modification and there is no unanimous recommendation on how this should be done. With the woofers to the inside the timbre of the loudspeakers seems more even, the bass foundation is better, and with this the midrange is heavier. The stage becomes narrower, and the spaciousness of the sound, its expansion – smaller. When we place the loudspeakers with the woofers on the outside, we get w very wide perspective and that without thinning of the stage, this stays continuous. The tonal balance will go higher and bass will not be that strong. Of course – the most important variable will remain the room, and where the loudspeakers are placed in it. Will they be close to the side walls, to the back wall, what will be placed between them, etc. In my room it was just like I just wrote.

I mentioned the change in the tonal balance – the Ketsus do not have a timbre typical for fullrange loudspeakers, there is no cut-off treble or bass. And this is probably what Eryk wanted, when he added the tweeter and when he modified the woofers. I would say, that the extension of the sound spectrum on both extremes is very good. The bass is not reaching very low, this is not there, but it is very resolved. And at the same time it is not very selective. This is no contradiction. With the Ketsus Special following the line of the bass or contrabass is a child’s play. More – the timbre of this subrange is so interesting, that we notice elements, melodic line, details connected to the technique of playing, which are lost somewhere even with loudspeakers stronger on bass. Here we hear it as if it would reach us better, as if it would be closer to us. And this is not an underlined or enlarged bass, or – even less – a contoured one.
The bass from the Ketsus is – how to say that – melodic. Its selectiveness, as well as of the rest of the frequency range, is not highest, and this is exactly the thing that surprises most, because this should result in a unified, crumpled bass, completely not like the one I described above. We do not have a strong kick, contour is weak, attack is blunt, but when the sound stabilizes, when we have sustain, it is very clear, clean and pulsating. The sound of the bass instruments is rather soft, but its “core” is active.
The midrange is audible a bit different. Like I wrote, the sound is big and the virtual sources are expansive. But when we play recordings with a large amount of elements, where the voice is only one of them, then the vocal is withdrawn, it is not placed forward. This is a matter of taste, in fact we do not know what is recorded, or how this should in fact sound, because live the special relationships are completely different to any recording; a disc is only an attempt to force upon us the impression, that we listen to a live performer. Anyway, the vocals are a bit in the shadow of other instruments. Even if the voice is clearly to the front, like on the mentioned Marilyn Moore disc, then it is not presented just before our nose – the same thing is true for small ensembles, like on the disc Songbird Eva Cassidy.
Interestingly, as shown by the Moore disc, it is not about lack of depth, but – as we already established – about reducing the size of the virtual sources. The dimension in depth is very good, the instruments behind the vocal are vivid, with breath. This is not a “muffled” sound.
This is because the treble is active and clear. This part of the sound spectrum, the upper treble is similar to the one we get from classic loudspeakers. It is vivid and I do not hear limitations from the top, I mean in comparison to classic tweeters. Its resolution and selectiveness seem slightly higher than the rest of the sound spectrum. But is not a very saturated treble – nice, slightly delicate, despite the significant amount of it, but not very deep. The top and bottom are only a kind of “tool” for the midrange, something, that allows it to reach further, than it could without them. This was also the reason for their application here.

Those are not typical “fullrange” loudspeakers, loudspeakers with a fullrange driver. Maybe because those aren’t typical fullrange speakers. On the other hand those are absolutely no classic three-way loudspeakers, or even 2.5-way ones. Anyway, when we would like to be accurate, we should talk about “one and two times half-way” speakers. Because when loudspeakers, where a woofer playing from the bottom is helped by a second woofer, but cut sharply from above are called two and a half way (when there is also a tweeter), then the same thing should be done for the tweeter. And here the treble and bass are only supports for the fullrange drivers. This is only a digression. Anyway – those loudspeakers sound in a different way than anything else. They show a big volume of the sound, their sound is very direct and quick. Yet the attack is rounded, and the selectiveness is in best case good. The tonal balance is shifted upwards, and only connecting them to a warm tube amplifier should get rid of that. For example the JAG 300B MkII, or Xindak MT-2 should be well placed here. I would add the Leben CS-600 to that. It would be in agreement with what Eryk said in the introduction and with his beliefs.
The sound stage is incredible and that was something with what you would have to learn to live, dishabituating from the flat, lifeless perspective produced by most other loudspeakers. A combination of incredible directness of the sound and slightly withdrawn perspective results in a different sound than from most other loudspeakers. If this is something for you – you will have to sort out individually. But it is worth to take into consideration the absolutely brilliant external design of those loudspeakers – it reflects good taste of Eryk. So buying the Ketsus we buy a part of him…


The loudspeakers were tested with the reference amplifier Soulution 710 and the Leben CS-300 [Custom Edition]. The source was the player Lektor AIR V-edition Ancient Audio and the CD player Burmester 089. The loudspeakers were placed on platforms Acoustic Revive RST-38, report HERE. The woofers were placed on the outside. The loudspeakers turned out to be sensitive to positioning – they sounded better, when the axes crossed quite far behind the listener.


Loudspeakers Ketsus Special, is a evolution of the loudspeakers Ketsus Superb, which we tested some time ago (HERE), with a worked out cross-over, slightly different drivers, etc, but still with the same, fantastic external design and chased detail.
Those are loudspeakers based on two fullrange drivers, supported from the bottom and top – respectively with two woofers made from woven carbon fiber and a metal dome tweeter. The woofers are placed on the side, this is the reason that you need to experiment at home, placing them on the inside and outside, and then decide which setting sounds better, and which set of characteristics suits us best. The tweeter, with a neodymium magnet is placed in a small enclosure in the shape of a water drop – something started by the company B&W and then also used by KEF. The driver is a bit inserted into the top side of the cabinet.
The cabinet is very narrow and deep. Two fullrange drivers are bolted to a fragment of the front baffle reinforced with aluminum, recessed a little into the loudspeaker. That was done to fit the grilles – those are on the level of the front baffle. In the place, where usually we find the dust cup, two felt rings were placed. The sides were milled in such a way, that they mimic wooden planks. The loudspeakers is covered by a high quality varnish, with the exception of two garnish rails – from the top and back, remaining in contrast to the rest of the cabinet. Those two elements are made from wood, and can be stained in various colors. The woofers are on the side and are also on the level of the side panel. Those are covered by a silver grille, placed in such a way, that I could not remove it. Those drivers work in a bass reflex chamber, with three ports on the back panel. On the back we have single wire terminal, quite mediocre (the same as in my Harbeth). The loudspeakers are placed on four, not very high, spikes.


  • CD player: Ancient Audio Lektor Air V-edition, review HERE
  • Phono preamplifier: RCM Audio Sensor Prelude IC, review HERE
  • Cartridges: Miyajima Laboratory SHILABE, review HERE), Miyajima Laboratory KANSUI, review HERE
  • Preamplifier: Ayon Audio Polaris III [Signature Version] with Re-generator Power Supply
  • Power amplifier: Soulution 710
  • Integrated amplifier/headphone amplifier: Leben CS300 XS Custom Version, review HERE
  • Loudspeakers: Harbeth M40.1 Domestic, review HERE
  • Headphones: Sennheiser HD800, AKG K701, Ultrasone PROLine 2500, Beyerdynamic DT-990 Pro; 600 Ω version, review HERE, HERE, and HERE
  • Interconnect: CD-preamp: Acrolink Mexcel 7N-DA6300 (article HERE, preamp-power amp: Acrolink 8N-A2080III Evo, review HERE
  • Speaker cable: Tara Labs Omega Onyx, review HERE
  • Power cables AC (all equipment): Acrolink Mexcel 7N-PC9300
  • Power strip: Acoustic Revive RTP-4eu ULTIMATE
  • Stand: Base; under all components
  • Resonance control: Finite Elemente Ceraball under the CD, Audio Revive RAF-48 platform under the CD and preamplifier
  • Pro Audio Bono platform under Leben CS300