Unison Unico 90 – Hybrid Dual Mono Integrated Amplifier

The Unison Unico 90 is a 100W dual-mono integrated amplifier into 8 ohms and 160W into 4 ohms, featuring a hybrid class AB circuitry that boasts zero feedback. In this case, the Italian brand used ECC83 and ECC81 valves to create a single stage to achieve the lowest possible output impedance.

The heart of this dual-mono class AB integrated amplifier is, as with the entire Unico line, a hybrid structure, characterized by the gain (and consequently the "character") due to a single valve stage. In this case, the valve complement is made up of ECC83 valves in a double triode totem configuration and ECC81 in a parallel totem configuration. The resulting circuit effectively provides six triodes per channel , positioned so as to form a single stage with adequate gain, while maintaining the lowest possible output impedance – a trademark of Unison Research.

Inside the output stage, three pairs of thermostable Class AB HEXFETs are used per channel.

These circuit choices are based on the experience of its bigger brother Unico 150 , which since 2015 has used many principles now also implemented on this integrated amplifier, obviously with lower power, but with a single two-stage circuit with zero global feedback.

In designing the Unico 90, the Italian company wanted to use as few active amplifier stages as possible. While the most powerful flagship, the Unico 150, has three active stages, the Unico 90 boasts lower power specifications but uses only a two-stage circuit.

Essentially, if we insert many amplification stages into a design, one after the other, the distortion structure becomes more complicated. This is why structural simplicity is a coveted goal in amplifier design.

Furthermore, in this Unico 90 innovative solutions have also been adopted for the preamplifier section which is completely passive , with a very low noise volume control, further reduced by an ALPS potentiometer which also improves the precision of the channel balance.

Input switching control decouples inactive source inputs, reducing crosstalk, using miniature, armored, purely mechanical relays positioned behind the connections.