Unison Research Unico 90 Hybrid Integrated Stereo Amplifier at Vinyl Sound Buffalo, NY USA

The Unico 90 is a Class AB hybrid integrated stereo amplifier from Unison Research (Treviso, Italy), available at Vinyl Sound in Buffalo, NY, USA. A zero-global-feedback design using only two gain stages -- an ECC83 and ECC81 totem-pole tube input stage driving a complementary MOSFET Hexfet output stage directly -- the Unico 90 achieves what Unison Research describes as the simplicity of the finest valve amplifiers within a powerful solid-state output topology. It produces 100 watts per channel at 8 ohms and 160 watts per channel at 4 ohms, with THD below 0.15% at 1 kHz at 1 watt. Six line inputs including two balanced XLR, a tape output, a volume-controlled subwoofer output, and 4+4 bi-wiring output connectors provide comprehensive system integration for two-channel and home theater configurations.

Two-Stage Zero-Feedback Architecture

The Unico 90's defining characteristic is its two-stage circuit -- input tube stage followed directly by the MOSFET power output stage, with only local feedback within each stage and zero global feedback around the amplifier as a whole. The input stage combines an ECC83 and ECC81 in a multiple-parallel totem-pole Class A configuration: by placing the two tubes in a totem-pole arrangement with multiple parallel devices, Unison Research achieves sufficient transconductance and current drive to directly control the gate capacitance of three pairs of complementary Hexfet MOSFETs per channel without an intermediate driver stage. The elimination of a third gain stage reduces phase shift, reduces the number of signal-path components, and places the tube stage's tonal character in direct, unmediated control of the output transistors. The thermostable Class AB MOSFET output stage maintains consistent bias across a wide operating temperature range, contributing to long-term reliability and tonal consistency during extended listening sessions.

Connectivity and System Flexibility

The Unico 90's six input complement -- three unbalanced RCA, two balanced XLR, and one bypass unbalanced -- covers studio-format balanced sources, consumer electronics, and home theater AV processor pre-out connections simultaneously. The bypass input disables the Unico 90's volume control for seamless AV processor level governance during surround sound use. A tape output and a volume-controlled subwoofer output with RCA connectivity complete the analog output specification. The 4+4 bi-wiring output terminal arrangement -- four pairs of binding posts -- accommodates bi-wired and bi-amplified loudspeaker connections. Output resistance below 0.4 ohms across all audio frequencies ensures that the Unico 90's frequency response remains consistent with complex, reactive loudspeaker loads.

Key Features

• 100 W/ch (8 ohm) / 160 W/ch (4 ohm): High output power from a two-stage hybrid topology for a broad range of loudspeaker designs and room sizes.
• Zero Global Feedback: No global feedback loop preserves the tube input stage's tonal character and impulse response integrity across the full output power range.
• ECC83 + ECC81 Two-Stage Topology: Tube input stage directly drives the MOSFET output stage without an intermediate stage, minimizing the number of signal-path components.
• Six Line Inputs with Two Balanced XLR: Two XLR and three RCA line inputs plus one unbalanced bypass input for home theater pre-out integration.
• Volume-Controlled Subwoofer Output: RCA subwoofer output tracks the amplifier's volume control for proportional bass integration with powered subwoofers.
• 4+4 Bi-Wiring Outputs: Eight binding posts support bi-wired and bi-amplified loudspeaker configurations.
• Thermostable Class AB MOSFET Output: Three Hexfet pairs per channel maintain consistent bias and output character across wide temperature variations.

Technical Specifications

Frequently Asked Questions

What is the Unison Research Unico 90?

The Unison Research Unico 90 is a zero-global-feedback hybrid integrated stereo amplifier from Treviso, Italy, using an ECC83 and ECC81 tube input stage driving a Class AB MOSFET output stage directly. It produces 100 watts per channel at 8 ohms and 160 watts per channel at 4 ohms through a two-stage circuit with six inputs including two balanced XLR and a volume-controlled subwoofer output.

How does the Unico 90 compare to the Unison Research Unico Nuovo?

The Unico 90 uses two tube types (ECC83 + ECC81) in a totem-pole input stage and produces 100 W/ch at 8 ohms with six inputs including two balanced XLR. The Unico Nuovo uses a single ECC83 tube in a parallel valve stage and produces 95 W/ch at 8 ohms with five RCA line inputs and no balanced XLR option. The Unico 90 is the higher-specified design with greater input flexibility and marginally more power; the Unico Nuovo is the more compact and accessible entry into the Unico hybrid series.

What does "zero global feedback" mean in the Unico 90?

Global negative feedback is a technique in which a portion of an amplifier's output signal is routed back to the input, out of phase, to reduce distortion and extend frequency response. While effective at reducing measurable distortion, global feedback can introduce time-domain artifacts -- particularly at high frequencies -- that some audiophiles associate with a less natural sound. The Unico 90 uses zero global feedback, meaning no signal is returned from output to input across the entire amplifier circuit. Only local feedback within individual stages is applied. This preserves the tube input stage's immediate, open character while the MOSFET output stage provides power delivery and current control.

Where can I buy the Unison Research Unico 90 in Buffalo, NY or the USA?

The Unison Research Unico 90 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 broader United States. Contact Vinyl Sound for current availability and to discuss system-matching options.