Интегральные усилители — Unison Research Triode 25 Black Edition

The Triode 25 Black Edition is a valve integrated amplifier from Unison Research, the Italian maker from the Treviso area. It belongs to a special Black Edition series that the maker created around three of its most successful products - Simply Italy, S6 and Triode 25. The cosmetic changes include a piano black wooden front panel, a black gun metal finish and updated lettering, while the circuit was revised in the signal path and in power management to lower distortion and raise output compared with the standard Triode 25.

Key specs that matter

Rated output is 50 W per channel in pentode mode and 30 W per channel in triode mode, against 45 W and 25 W for the regular version, which Unison Research describes as gains of 10% and 20% respectively. Power valves operate push-pull in Class AB, and bandwidth at -1 dB runs from 10 Hz to 50 kHz. Sources connect through three RCA line inputs together with USB, coaxial SPDIF and Toslink, a stereo RCA subwoofer output and one line output. The chassis measures 30 x 45 x 20 cm and weighs 20 kg.

Engineering and use context

All valves are Gold Lion types - two ECC83 and one ECC82 triodes in the preamplifier section and four KT77 in push-pull for the power stage, supplied as matched sets. The pentode setting is an ultralinear connection with the screen tap at 60%, while the triode setting trades power for the triode operating character. A front switch sets global feedback at 10 dB or 12 dB, and the maker notes that this changes damping factor, bandwidth and distortion. Output bias is fixed but partly adjustable by the owner for both channels through a bias selector. The power supply was reworked so that the anode voltage of each valve is decoupled, with polypropylene capacitors added at selected points. Input switching uses micro relays with gold-plated silver contacts to stop crosstalk from unselected sources, and Return GND technology gives every input its own short ground return path. Where possible the signal travels inside coaxial cable. The internal DAC3 module accepts PCM up to 384 kHz and native DSD up to DSD256 over USB, DoP up to DSD128, and up to 192 kHz on Toslink and SPDIF.

Pairing

The unfiltered subwoofer output is intended for an active subwoofer and keeps the full signal from the amplifier rather than a crossed-over feed. With a computer or streamer on USB and a CD transport on the coaxial or optical input, no separate converter box is required.

Alternatives

Unison Research also makes the S6, a pure class A valve integrated amplifier built around six EL34 output valves.