TRIODE 25 Black Edition
Description
The Triode 25 is one of the most iconic models in Unison Research history. Born in Treviso as a celebration of the company's 25th anniversary, it quickly became a statement in its own right about what an affordable tube amplifier with serious ambitions should be. The Black Edition is not a cosmetic update. It's a reimagining of the circuitry from the signal path to the power supply, with new tubes, a new aesthetic and a digital interface that the original lacked.
The standard Triode 25 used EL34 tubes. The Black Edition switches to the KT77 Gold Lion — and this is not just a replacement: the KT77 is a bow tetrode with characteristics that are between the EL34 and KT88, but with its own harmonic structure. Compared to the EL34, it gives a slightly more controlled and extended bass, while maintaining the EL34’s inherent midrange density. Unison Research chose this particular tube after listening tests — and this decision determines the sound character of the entire model.
Output stage — four KT77 Gold Lion in a push-pull configuration, a pair for each channel. Signal stages: two ECC83 Gold Lion and one ECC82 Gold Lion. All tubes — selected, with confirmed characteristics.
The Triode 25 Black Edition is one of the few amplifiers that allows you to switch between modes directly while listening. In triode mode (30 W per channel), the amplifier sounds softer, with pronounced tube harmonics and a more “rounded” sound image - a classic choice for vocals, jazz, chamber music. In ultralinear mode with a 60% tap (pentode mode, 50 W), the dynamic range and control over the bass increase - an advantage when working with less sensitive acoustics or complex orchestral recordings. The feedback level is 10 or 12 dB, also switchable.
The most important innovation of the Black Edition is the input switching system. Microrelay with Return GND technology - the same scheme used in top Unison Research amplifiers. Unused inputs are grounded, which eliminates crosstalk between channels and switching noise. The audio signal, where technically possible, is transmitted in a shielded coaxial cable. Polypropylene capacitors in the power supply units are another detail borrowed from more expensive models. Bias adjustment is manual, individual for each output tube: this gives greater control over the sound and power compared to the automatic Bias in the standard version.
The entire Black Edition series has a built-in DAC3 DAC module. Inputs: USB-B (up to 32 bit / 384 kHz, DSD up to DSD256), optical Toslink and coaxial S / PDIF (up to 24 bit / 192 kHz). Three linear analog RCA inputs. Line output and output for an active subwoofer (stereo RCA). Bandwidth - 10 Hz - 50 kHz (-1 dB).
Black lacquered wooden front, dark anodized metal chassis, bronze accents, updated typography - the Black Edition looks like a separate model, and not a repainted version of its predecessor. Weight 20 kg with dimensions 30×45×20 cm. The amplifier works comfortably with speakers with a sensitivity of 87 dB and above, which makes it a much less capricious partner than single-ended SET amplifiers. A natural tandem is Opera Loudspeakers Classica line speakers or any high-quality bookshelf or floor-standing speakers with an impedance of 4–8 Ohms.
