The Unison Research Unico 90 is a class AB hybrid integrated amplifier with zero feedback, as the most precious valve amplifiers use only two stages. The heart of the Unico 90 circuit is found in its hybrid structure. All of the gain, and subsequently the “character” of the amp, is determined by the only tube stage made with ECC83 and ECC 81in particular multiple-parallel-totem-pole.
Unison Research Unico 90 Specs:
Output power: 100+100 W RMS su 8Ω / 160+160 W RMS su 4Ω
Frequency response: -1dB @ 12Hz e 45kHz -3 dB
Input impedance: 21Kohm // 300pF
Input sensitivity: 860mV RMS
Input stage: Pure A class, double triode totem pole ECC83 and parallel totem pole ECC81 This single-stage due to the particular circuitry is able to amplify the input signal and drive directly the power stage.
Output stage: Class AB thermostable, complementary Hexfet (3 pairs for a channel)
Number of stages: 2, This amplifier due to the particular circuitry is realized by only two stages: input stage and output stage, and use only local feedback