Unison Research Dúe Integrated Tube Amplifier

Beautifully Crafted In Italy

This is the version with both DAC and phono stage
This is a flawless showroom demo.
 Unison Research Unico Dúe Tube Hybrid Amplifier with MM Phono and DAC Inputs
Factory sealed with ac cord, remote, all packing and double boxed.
Full 3 years Mfg warranty with local service in the USA.



Sales tax is 7.75% in California

Buy with confidence from one of the USA's longest existing, most knowledgeable audio dealers:
Gene Rubin Audio
Established way back in 1979!

Go ahead and google Gene Rubin Audio, read the forums, read the reviews, read my ebay feedback, you are dealing with the best customer service in the audio business

Franchised dealer for: LFD, Rega, Heed, Palmer, Pure Fidelity, Unison Research, LIO by Vinnie Rossi, Fyne Audio, Belles, Exposure, Aurender, Hana, Koetsu, Ortofon, Sutherland Engineering, Croft, Harbeth, Spendor,  Clearaudio, Acoustic Signature, Dynavector, Quadraspire, Chord Company, Fosgate, Sound Anchors, Music Hall, Audience, Dali, Audio Desk Systeme, Creek, Milty, KAB, Q-UP, Furutech, and more.!

"I just spent a few days listening to the new Due. This is a really great amp. It is very involving, beautifully built and  approaches the sound of the LFD amps. There is no doubt this amp is a bargain as it includes a fine DAC and built in phono stage!"--Gene Rubin

PLEASE NOTE: Both the Phono and Dac are INCLUDED with the new DUE.

Unico Due is the latest amplifier from Unison Research. Unico Due  benefits from Unison Research’s decades of experience in design and  production technology. It maintains all the best qualities that made its  predecessor a runaway success and introduces new and enhanced features.

Circuit

The electronic circuitry of the Unico Due has been completely  redesigned. While maintaining the qualities that made the Unico range  such a legend in the audio industry, key improvements have been made  that are nothing short of ground-breaking. Firstly, the power supply  circuits have been enhanced thanks to a substantial increase in  filter capacitance size and to a new high quality shielded and  encapsulated power transformer. The new power distribution system of the  audio power output stage combines space optimization, superior circuit  solutions and improved assembly and service solutions.

The heart of the preamplifier stage in based around two ECC83 double  triodes (one per channel), configured as a gain stage followed by a  cathode-follower. This circuit’s low output impedance efficiently drives  the power stage that follows. The final choice of the type of valve and  the circuitry used was made following extensive listening tests,  after we experimented many equally high performance valve-based  solutions and configurations in our test laboratory.

Features

The Unico Due aims to satisfy even the most demanding users and offers the following features:

• One USB input to the Unico Due’s internal DSD 128 bit DAC.

• One direct analogue line output from the Unico Due’s internal DAC, which allows it to be used as a stand-alone DAC.

• A low impedance subwoofer output (SUB) with variable output level from the preamp for connection to an active subwoofer.

• AV input that allows the Unico Due to be connected to a home  theatre system: pressing the “push” button on remote control, the Unico  Due will automatically select the chosen channel at a user-configured  volume level.

• Dynamic Class A power amplifier biasing where the power transistors  never turn off completely. This provides excellent sound results even  at low volume.

The Unico Due offers four inputs: three analogue inputs and one USB  digital input. The input selection uses sealed miniature relay switches  to preserve the delicate low-level signals, whereas the volume  regulation is based on an integrated high-precision,  high-performance resistor array followed by a set of digitally  controllable analogue switches, used in reference products and capable  of 120 dB of attenuation with 0.5dB steps. The power output stages are  solid state and use a completely original combination of bipolar and  MOSFET transistors. Furthermore, instead of designing in  standard differential input stages, a sophisticated symmetrical BJT  circuit is used that has moderate gain and very high intrinsic  linearity, with separate feedback loops for AC and DC signals.

Thanks to its low distortion, we were able to configure it to have a  very mild feedback level. The power output stages of the Unico Due  feature a non-switching bias control circuit which prevents the current  in the output transistors to reach zero. This greatly reduces distortion  at low and very low listening levels and guarantees the highest  sound transparency in any condition.

The power output devices are connected in a “super symmetrical”  configuration, i.e. negative and positive signal polarities are handled  separately by a combination of N and P type devices.

You may ask yourself why we should worry about minimizing the  distortion of the solid state power output stages when there is a valve  pre-amplifier section that will add a small amount of distortion. The  reason is very simple: our goal was to create an integrated amplifier  whose “sonic character” was mainly dominated by the valve section, but  with enough power to comfortably drive any loudspeaker system.

To improve performance further, we added regulated power supplies not  only when it was absolutely necessary, but also in any part of the  circuit where this would bring sonic improvements over using simple  filtering. In the Unico Due there are no less than ten stabilized power  supplies with output voltages ranging from 15V for low  signal operational amplifiers to the 300V required by the valves in the  preamplifier stage.

Particular attention was paid to the output power stage supply.  Considering the high value, impulsive, almost intractable nature of the  current that the power stage has to handle, we decided to adopt a bold  solution. We used large-value, high-quality capacitor banks, some of  which are placed close to the power transistors to minimize the path to  the current pulses. The supply tracks on the PCB are generously sized,  having a thickness of 105um (3oz), and the ground return tracks have  been designed with extreme care. Obviously difficult choices like these  can create a number of design and realization difficulties which many  engineers may decide to give up on and find easier solutions, but the  engineers at Unison Research embraced these challenges and solved them  without compromising on quality and performance. The final result is a  design where almost 25% of the entire surface of all the PCBs in the  Unico Due is dedicated to supplying power to the output devices!

The same meticulous attention was paid to managing the low-level  audio signal. Starting with the gold-plated input connectors, to the  speaker sockets that are also gold-plated, robust, versatile and  completely insulated according to the latest regulations. Furthermore,  the audio signal is fed through circuitry using the highest available  quality of components: high-precision sealed micro-relay  switches, carefully selected Mundorf capacitors, low tolerance  metal film resistors, ceramic tube sockets with gold contacts, and much  more.

USER INTERFACE

INPUT SELECTION

You can select the input source by rotating the “selector” knob or  pressing the dedicated buttons on the remote handset. The selection  sequence is circular; the currently selected input is indicated by the  front panel LEDs.

VOLUME SELECTION

The volume setting can be varied by rotating the “volume” knob or  pressing the dedicated buttons on the remote handset; the level is  indicated by the front panel display which shows a number between 0.0  (min level) and 9.9 (max level).

TAPE/MONITOR MODE

Switching to tape/monitor mode makes another line-level input  available (see Notes about inputs); you can activate it with a short  press on the selector knob. Another short press switches it back to the  selected input.

MUTE

The mute function immediately applies the maximum attenuation to the  currently selected input. You can activate it by a short press on the  volume knob; the level shown on the display doesn’t change but the mute  status is indicated by the status LEDs. Another short press disengages  mute.

OSD

The OSD function puts only the output power stages in stand-by mode.  When switched back, the devices starts without requiring warm up. The  DAC line output remains active.

DISPLAY OFF

When the display is set to off, the display turns off after 20  seconds of inactivity and turns on automatically when any single  function is activated.

BALANCE

Hold the volume knob pressed for a few seconds to adjust the channel  balance; thedisplay will then show the balance level: the first digit  indicates the level of the left channel, the second digit indicates the  level of the right channel; turning the knob adjusts the balance level.

AV MODE

The AV function allows you to connect Unico Due to an AV playback system and you can

choose the AV input and pre-set the volume level. Once set, pressing the "Push" button

on the Unico Due handset will switch to the AV input selected and adjust the volume to

the previously pre-set level.

SETTING AV MODE

Select the desired channel and volume using the input and volume  selector knobs. Hold down the selector switch on the monitor, press the  OSD button until the display flashes, then release the button.

Pressing the "push" button on the Unico Due remote control will  automatically switch to the selected channel on the selected volume.

DISABLE AV FUNCTION

• Put Unico Due into mute with a short press of the volume knob;

• Hold down the input selector knob to activate the monitor function, then press the OSD button until the display blinks;

• Release the button; after this, pressing the “Push” button on the handset will not do anything.

POWER PROTECTION

Unico Due is equipped with a sophisticated microprocessor-controlled  system that monitors its power output. In case the power output is high  over an excessively long time, Unico Due gradually decreases the volume  level to a more sustainable level to protect the power devices.

Technical Specifications:

Output power: 100+100W RMS into 8 Ohms, 180+180W RMS into 4

Ohms, 290W+290W RMS into 2 Ohms

Filter capacitance: 80,000uF

Output stage: Dynamic Class A power BJT double complementary

pair, “Super-Symmetric” configuration

Biasing: Dynamic Class A

Valves: 2 x ECC83 (12AX7)

Inputs: 3 analogue line (RCA), 1 digital (USB), 1 tape RCA

Analogue line Outputs: 1 tape (RCA), 1 stereo subwoofer (RCA), 1 DAC

Speaker output connectors: 4 + 4 to allow for Bi-Wiring

Dimensions: 43.5 x 43 x 13 cm (W x D x H)