Unison Research – UNICO 150 – Class-A Hybrid Integrated Amplifier

Unison Research – Unico 150 – Class-A Hybrid Integrated Amplifier

The Unico 150 is a hybrid integrated amplifier developed according to specific sonic and scientific criteria set by the design team at Unison Research. These criteria led to a product completely different from anything else Unison Research has ever released. That means it’s also different from every other amplifier—valve or solid state—on the market.

The research at Unison Research led to two circuit performance standards that are considered essential for excellent performance: a 3-stage circuit and a 2-stage circuit, both in counter-zero. The first type, used in the new Unico 150, is more suitable for integrated amplifiers with higher-than average power. The second type is a more effective application for lower powered amplifiers. Both of these approaches allow Unison Research to reach a standard of linearity almost impossible with the usual technologies that are matched to single-ended driving capabilities. In fact, the linearity of these new designs is downright remarkable, and typical of the best solid-state amplification available.

Circuit
The heart of Unico 150 circuit is found in its hybrid structure. All of the gain is determined by the first two tube stages. These stages are made with the triodes configured so that they present limited gain with the least output impedance possible.

All capacitors touched by the signal are the types that exhibit very low loss and excellent behavior at high frequencies. The polypropylene used for these resistors has been widely used for supporting the speed and acceleration of the signal path. Four Mundorf capacitors with very low stray inductance are used in each channel to provide a final energy reserve. As usual for Unison Research, these electrolytic caps are constructed from very Italian Itelcond and have a low stray inductance, and are doubled on each branch to lower the inductance further.

Power
When designing the Unison Research Unico 150, consistency was one of the primary goals and is maintained practically at almost every level of power delivery, with the partial exception of the eighth highest at maximum power (a condition that no actual audio signal may take). This is due to the linearity the first two stages of valves, and direct coupling between these and the MOSFET output.

Preamplifier
The preamp section of the Unico 150 also incorporates a number of innovative solutions. The preamp section is totally passive. An ALPS potentiometer is shielded in four sections, parallel in pairs especially in the region of high attenuation. The selected sources are connected one at a time in order to interrupt the ground loops associated with the unused connections.

Switching is performed by purely mechanical miniature relays that are shielded and placed behind the sockets. The terminals of the hot springs not used are deflected toward their ground in order to eliminate the risk of capacitive coupling through the movable contacts. The balanced inputs are not obtained by electrical means; instead, transformers are used, which allows a truly balanced transmission of signals in addition to other types of galvanic isolation.

Construction
The Unico 150 is a dual mono amplifier with power transformers capable of delivering 400 + 400 VA continuously. The power MOSFET of each channel can handle power up to 1200W and stationary currents up to ±50A. These circuits, of course, are protected and are weighted on 70% of their maximum specifications so to maintain an adequate margin of safety without affecting driver capabilities.

Conclusion
Unison Research has accounted for every detail, and thousands of simulations have been carried out in our research labs, to arrive at the Unico 150 integrated amplifier. Unison Research has built dozens of prototypes to test every conceivable variation until they have realized our goals through extensive listening tests.