Unison Research Unico Due Hybrid Integrated Stereo Amplifier at Vinyl Sound Buffalo, NY USA

The Unico Due is a hybrid integrated stereo amplifier from Unison Research (Treviso, Italy), available at Vinyl Sound in Buffalo, NY, USA. A completely redesigned evolution of the original Unico integrated that made Unison Research's hybrid amplifier range an international benchmark, the Unico Due introduces a substantially enlarged power supply filter capacitance of 80,000 µF, a new high-quality shielded and encapsulated power transformer, and a Dynamic Class A power BJT output stage in a "Super-Symmetric" double complementary pair configuration. It produces 100 watts per channel at 8 ohms, 180 watts per channel at 4 ohms, and 290 watts per channel at 2 ohms. The tube complement of two ECC83 valves establishes the Unico Due's sonic character in a pure Class A tube input stage feeding the high-current BJT output stage directly. A USB digital input and DAC output expand the amplifier's connectivity beyond pure analog integration.

Dynamic Class A BJT Output Stage and Super-Symmetric Configuration

The Unico Due's output stage departs from the MOSFET Hexfet topology used in the Unico 90 and Unico 150, employing instead a BJT (bipolar junction transistor) configuration in a "Super-Symmetric" double complementary pair arrangement. BJT output stages are distinguished from MOSFETs by their lower output impedance (contributing to tighter bass control) and their ability to source and sink current with very high speed -- characteristics Unison Research has optimized through the Super-Symmetric layout, which places complementary NPN and PNP transistor pairs in a geometrically symmetric circuit arrangement to minimize even-order distortion through signal-path symmetry. Dynamic Class A biasing adjusts the output stage's operating point dynamically in response to signal demands rather than maintaining a fixed high-current idle bias -- achieving Class A-like linearity in the operating region most frequently encountered in music reproduction without the full heat dissipation of a static Class A design.

Power Supply and Connectivity Improvements

The Unico Due's 80,000 µF filter capacitor bank is a substantive engineering upgrade over its predecessor, providing significantly greater charge storage for instantaneous high-current demands from complex loudspeaker loads. The shielded and encapsulated power transformer eliminates the magnetic field leakage that can couple noise into sensitive ECC83 tube circuits when transformer and audio board share an enclosure. Three RCA analog line inputs, one USB digital input, and a tape input cover the core source connectivity requirements. Analog outputs include tape (RCA), a stereo subwoofer (RCA), and a DAC output. The DAC output allows the Unico Due to serve as a high-quality DAC feeding an external amplifier or headphone stage. The output stage's current delivery capability into 2-ohm loads (290 W per channel) makes the Unico Due suitable for driving electrostatically loaded or very demanding loudspeaker designs.

Key Features

• 100 W/ch (8 ohm) / 180 W/ch (4 ohm) / 290 W/ch (2 ohm): High output power with current reserve sufficient for the most demanding loudspeaker loads, including electrostatic and ribbon designs.
• 80,000 µF Filter Capacitance: Substantially enlarged power supply reservoir provides high-current instantaneous delivery for complex musical transients.
• Super-Symmetric BJT Output Stage: Double complementary BJT pair in Dynamic Class A biasing minimizes distortion through topological symmetry and dynamic bias management.
• ECC83 Tube Input Stage: Two ECC83 valves in the input stage establish the amplifier's sonic character in pure Class A before the BJT output stage.
• USB Digital Input: Integrated USB DAC allows computer audio playback directly through the Unico Due without a separate DAC component.
• DAC Output: Dedicated DAC output allows the Unico Due's built-in digital conversion to feed external components.
• Shielded Encapsulated Power Transformer: New high-quality transformer with shielding eliminates magnetic field coupling into the tube input stage.

Technical Specifications

Frequently Asked Questions

What is the Unison Research Unico Due?

The Unison Research Unico Due is a hybrid integrated stereo amplifier from Treviso, Italy, using two ECC83 tube input valves driving a Super-Symmetric Dynamic Class A BJT output stage. It produces 100 W/ch at 8 ohms, 180 W/ch at 4 ohms, and 290 W/ch at 2 ohms, with an 80,000 µF power supply filter capacitor bank, a USB digital input, and DAC output.

How does the Unico Due differ from the Unico 90?

The Unico Due uses a BJT Super-Symmetric double complementary pair output stage with Dynamic Class A biasing, producing up to 290 W/ch at 2 ohms and featuring an 80,000 µF power supply. The Unico 90 uses a complementary MOSFET Hexfet output stage with three pairs per channel, producing 160 W/ch at 4 ohms. The Unico Due's BJT topology offers a characteristically tighter, faster bass response compared to the MOSFET stage, while its significantly larger power supply capacitance provides greater instantaneous current reserve for loudspeaker transients. The Unico Due also adds a USB digital input and DAC output absent from the Unico 90.

What is Dynamic Class A biasing?

Dynamic Class A biasing is a technique in which the output stage's idle bias current adjusts in response to the instantaneous signal demand. At low signal levels, the bias current is maintained high enough to keep the output devices operating in Class A -- where both devices conduct simultaneously throughout the signal cycle. As signal amplitude increases, the bias adjusts to allow the output stage to transition gracefully into Class AB operation, reducing heat dissipation without introducing the abrupt crossover distortion associated with conventional Class AB amplifiers. The result is Class A linearity in the normal listening range with Class AB efficiency at high output levels.

Where can I buy the Unison Research Unico Due in Buffalo, NY or the USA?

The Unison Research Unico Due is available at Vinyl Sound in Buffalo, NY, USA. Vinyl Sound is an authorized Unison Research dealer serving customers across western New York and the United States. Contact Vinyl Sound for current availability and system integration advice.