Unison Research S6, Simply Italy & Triode 25 Black Edition

KT77 has a unique history. GEC in England introduced the KT77 valve in the late 1950s as the ultimate medium-power audio power valve. KT77 valve was designed as a drop-in replacement for EL34. KT77 employed an internal construction resembling 6CA7 and GEC called it "Kinkless Tetrode" which is what the KT prefix stands for. Earlier power valves had "kink" in their power curve, resulting in non-linearity. GEC's marketing claim was that their design eliminated this non-linearity, thus optimizing the KT77 valve for high-fidelity audio applications. The KT77 was known as the ultimate EL34 for audiophile use. The current production Genalex Gold Lion KT77 was introduced in recent years to recreate the original magic of the KT77. Gold Lion KT77 has a smooth texture and wonderful balance and is worthy of consideration as a premium upgrade for any EL34 amplifier. KT77 valves offer a much deeper and more open sound with a cleaner high end. The re-issue of these valves allows you to experience their sound and find the perfect fit to suit your personal preference. Featuring gold-plated grid wire and beautiful artwork, these valves are built with heavy glass and ruggedized plates, ensuring they can handle substantial abuse while maintaining their performance. 

Cathode Capacitor Less (CCL) technology eliminates the need for electrolytic capacitors in valve power stages. Typically, auto-bias systems utilize a resistor on the cathode along with a high-value electrolytic capacitor bypass. However, these capacitors introduce distortion, low frequency signal phase shifts, and coloration into the sound. To overcome this issue, in the Black Edition series, we made the decision to completely eliminate the auto-bias system. In other words, there are no cathode capacitors used whatsoever! This enhancement enables us to extend the bandwidth towards the lower frequencies, resulting in a faster, more detailed sound. Additionally, it provides even more power to the valve, which would otherwise be dissipated by the resistor in the auto-bias configuration. 

In the Black Edition series, the input selector uses the same technology used in our flagship products - Reference Pre and Absolute. Modern audio sources often have output voltages that can vary significantly, leading to potential cross-talk between inputs when using a traditional input selector. The input audio signal is selected using armoured micro relays with gold-plated silver contacts. Ground connections have been completely redesigned using Return GND technology. Inputs not in use are connected to load resistors. This ensures that the signal path (and its ground) not in use is closed at the RCA connector, preventing the signal from propagating through the circuit board. These enhancements result in a significant reduction in cross-talk between channels, resulting in clearer and more defined sound. They also improve microdynamics and soundstage stability.

For the Black Edition series, Unison has chosen to apply the same surface treatment to the wood as that used for the wood in musical instruments like a stylish grand piano. Achieving this exquisite finish involves several meticulous steps. The panel is sprayed with a primer to fill all the micro-cracks and porosity of the wood. After drying for several hours, the panel is progressively sanded with increasingly fine sandpaper. Once this process is completed, the wood is carefully cleaned, and the first coat of black varnish is applied. After the initial varnish coat dries (within 16 hours), a layer of clear varnish is applied. Another layer of clear varnish is applied after 3 hours. The panel must then dry for at least 3 days before the polishing process begins. Once the high-gloss varnish is dry, the panel is rubbed down with very fine grit sandpaper and water to prepare it for polishing. The panel is polished using a special polishing cap, followed by re-polishing with a polishing paste and a synthetic polishing cap. Finally, all traces of polishing paste are removed with a microfiber cloth, and the panel is meticulously inspected by experienced craftsmen. To achieve a perfect result, all these processes must be carried out with extreme care and without the slightest error. 

The stainless steel undergoes a chemical nickel-plating process to achieve the characteristic Black Gun Metal color. To provide additional protection and ensure maximum resistance to external contaminants, a transparent acrylic coating is applied using cataphoresis. This coating offers unparalleled resistance to pollutants, oxidation, and other environmental factors. By creating a barrier between the metal substrate and the external environment, it renders the surface inert and nearly impervious to damage. 

In the Black Edition series, each amplifier includes a stereo sub output. This unfiltered line-level output is taken directly from the amplifier's output, ensuring consistent sound timbre. The new Black Edition series are equipped with 3 digital inputs - USB (PCM up to 384kHz, DSD native up to 256x and DoP up to 128x), Toslink, and SPDIF (up to 192kHz as standard). Info and photos by Unison Research.