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This review first appeared in the December 2011 issue of hi-end hifi magazine High Fidelity of Poland. You can also read it in its original Polish version here. We publish its English translation in a mutual syndication arrangement with publisher Wojciech Pacula. As is customary for our own articles, the writer's signature at review's end shows an e-mail address should you have questions or wish to send feedback. All images contained in this review are the property of High Fidelity or Eryk S. Concept. - Ed

Reviewer: Wojciech Pacula
CD player: Ancient Audio Lektor Air V-edition
Phono preamplifier: RCM Audio Sensor Prelude IC
Cartridges: Miyajima Laboratory Shilabe, Miyajima Laboratory Kansui
Preamplifier: Ayon Audio Polaris III Signature Version with Regenerator power
Power amplifier: Soulution 710
Integrated amplifier/headphone amplifier: Leben CS300 XS Custom Version
Loudspeakers: Harbeth M40.1 Domestic
Headphones: Sennheiser HD800, AKG K701, Ultrasone PROLine 2500, Beyerdynamic DT-990 Pro 600Ω version
Interconnects: CD-preamp: Acrolink Mexcel 7N-DA6300, preamp-power amp Acrolink 8N-A2080III Evo
Speaker cable: Tara Labs Omega Onyx
Power cables (on 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 player, Acoustic Revive RAF-48 platform under the CD player and preamplifier. Pro Audio Bono platform under Leben CS300
Review component retail: 24.000zł in Poland
Usually at this opening juncture of a review I cover company philosophy, brand history and product specifics. But since Eryk Smólski of Eryk S. Concept had interesting things to say, I decided to give him the microphone. "The Ketsus Special is the newest version of the Ketsus designed whilst considering two of the most difficult criteria yet maintaining the original size and shape which women love. The criteria were filling rooms of about 50m² with sound; and be able to accommodate SETs which rarely produce more than 10 watts. To achieve this versus the 150/200w previously recommended and 4Ω impedance I had to raise sensitivity by 3dB to 91dB. This was a real challenge as I needed to maintain the frequency response and because the sidefiring woofers despite theoretically ‘omnidirectional bass’ produce less pressure.


"An additional goal was to flatten the response and guarantee that even with modern harsh/dry/fast transistor amplifiers the sound will remain balanced and musical. Practically speaking the enclosure remained mostly unchanged save for the now concealed woofers and small adjustments to the dimensions (now 14 x 40.5 x 101cm without spikes) and a weight increase to 30kg/ea. The cabinet walls are a combination of 20/30/40mm thickness. The finish is white pearl piano gloss (not an automotive varnish) and the back and bottom panels are Ebony. The damping in the woofer chamber changed but the materials themselves are still sheep’s wool, sponge, bitumen mats and felt.


"The decisive changes include hiding the woofers as suggested by our customers for improved cosmetics. I also decided to remove the so-called SuperTweeter connector on the back because it caused confusion or was not used at all. I designed the new woofers from scratch as well as the widebander and slightly modified the super tweeter. The crossover frequency is at 200Hz and 14kHz, the latter achieved with an atypical connection of the super tweeter since the widebander makes 20kHz with some rolloff. This is a very different 2.5-way system based on paralleled drivers to fulfil the reliability requirement with 2 times lower operating temperature and better power load vs. distortion behavior.

"In addition the woofers have greater throw than before and bass compression is lower. On the back we have three bass-reflex ports where even at high woofer amplitudes the ports don’t overload which could otherwise result in a leaky sealed cabinet with significant distortion. The woofers have 100% carbon diaphragms and very advanced motors (among other things built-in magnetic field correction circuits and improved cooling). The widebanders have cellulose diaphragms with special correctors so the entire speaker design really is new, just the external dimensions remain. Of course we also had a new crossover made in three sections. Based on auditions I settled on PIO capacitors for the super tweeter, bipolar foil capacitors and metalized 1% resistors. The woofer coils have low internal resistance in the range of 0.1Ω. With this construction the filters have especially profiled slopes."