Unison Research Simply Italy Integrated Class A Valve Amplifier

The Unison Research Simply Two was certainly one of the worlds most successful integrated valve amplifiers, a product widely acclaimed both by audiophiles and the specialist press.

Taking our cue from the Simply Two, we decided to redesign and produce a new, small, integrated valve amplifier: called SIMPLY ITALY. It is similar in many aspects of the electronic design to the earlier model, but with a new, more modern appearance than the famous Simply Two.

Faithful to Unison Research tradition, this new amplifier is also  an Integrated. We are convinced that integrated amplifiers can offer many advantages, not only by simplifying the whole music replay system, but more importantly because of the improvements to sound quality that can be obtained by this method. Another important aspect lies in the considerable cost reduction (a single chassis, less cabling, both for power supply and interconnects).

The design of an integrated amplifier is considerably more complex and critical that that of a  separate pre or power amplifier.  Consider for example the fundamental importance of avoiding interference between each single component and between each stage (power supply, control, preamplifier, power output). Our experience over many years in designing and producing integrated amplifiers has enabled us along the way to create models which have become highly-valued classic pieces;  one example amongst many being the famous Unison Research ABSOLUTE.

Compared to its predecessor the Simply Two, the new  SIMPLY ITALY presents a number of modifications and changes,  however it maintains the same musical balance, functionality and is still extremely reliable. The output power - approximately 12 watts per channel - remains the same, however the output impedance is now 6-Ohms, making the amplifier suitable for use with both 4-Ohm and 8 Ohm loudspeakers.

The appearance in design, as noted, has undergone a radical change. The wood detailing is now confined to the front panel, but embellished by the addition of contrasting circular inserts , also of wood, which give a more attractive look to the controls.

Two satin stainless-steel bands beneath the valves add a touch of refinement, and also assist the thermic isolation of the electronic circuit and output transformers which gives a clear benefit to sound quality and overall reliability of the amplifier.

All amplifying stages are strictly valve-based, and the  circuit design adopted ensures that all the valves operate in pure Class-A.

Since the very beginning Unison Research has dedicated itself to the design, development and manufacture of output transformers, conscious of the vital importance of these complex elements in the pursuit of the best sound quality. Very few manufacturers in the world can boast of being able to produce high-quality transformers. Thanks in large measure to these particular transformers it has been possible to create an output stage for Simply Italy consisting of one EL34 in single-ended ultra linear configuration. Indeed this mode of operation is made possible by a particular development of the output transformers which in practice allows the pentode EL34s to operate almost as if they were triodes.

The preamp and driver stage of the power output is entrusted to ECC82 twin triodes. These valves provide excellent linearity and an almost complete absence of uneven order harmonic distortion.

The first amplifying triode of the input stage has zero feedback, both global and local. To obtain this, the classic cathode auto-bias circuit was eliminated and replaced by ionic bias, the only type able to guarantee absence of feedback and minimum phase rotation of the amplified signal.

It is interesting to note that this allows the possibility to choose the level of overall feedback of the amplifier, which in turn provides a better interface with the loudspeaker, the cables and the listening environment.

The preamplifier valve filaments are DC - supplied in order to prevent any residual AC component from interacting with the signal to be amplified.

The same care and attention reserved for the amplifying stage design was also given to the power supply. The Sinfonia power-supply  transformer is not a normal toroidal transformer, but the result of a project aimed at reducing electrical loss and containing dispersed magnetic flux.

The ideal power supply would be dual-mono, a solution however requiring space and adding weight. In the Simply Italy a type of power supply which might be called  Quaso-Dual-Mono has been adopted. In fact, apart from the power transformer and first filter stage the power supply is doubled, separating all preamp stages to the benefit of low crosstalk and low distortion.

The Simply Italy is supplied with an infra-red remote handset which allows the user to interface with the microchip control circuit; this manages control of analogue volume via an ALPS motorized potentiometer of the prestige RK27 series.

Four large gold-plated terminal connectors  allow any kind of loudspeaker cable to be used, and the loudspeakers can be between 4 and 8 ohms impedance.

In the Simply Italy nothing has been left to chance; the control knobs for example, turned from non-magnetic stainless-steel of large diameter and weight give a smooth flywheel effect  with excellent `feel` and rotational precision. The wood parts, important for the aesthetic design also play an important role in damping chassis resonance, and thus assist the delicate electronic parts, valves etc to perform at their best.

The adoption of refined circuit solutions which are out of necessity, complex; the generous size of components such as capacitors and transformers, and the decision to make Simply Italy a very compact amplifier have required that special attention in this project be paid to the chassis and internal layout.

As in all Unison Research projects, great care has been taken with the fundamentals such as power-supply track sizing, careful routing of both earthing and signal runs; the overall robustness, the ease of  build and servicing, and the provision of adequate ventilation for the internal circuit.

To ensure the best performance and best reliability over time of all the components used in Simply Italy have been carefully chosen and selected, from resistors, many of which are anti-inductive, to electrolytic capacitors, valve sockets in pure ceramic, to the printed circuit boards in vetronite.

Specifications

• Type: Stereo Integrated Valve Amplifier
• Output stage: Single-ended, ultralinear, Class-A
• Output power: Approx. 12 watts per channel
• Output impedance: 6 Ohm
• Input impedance: 47kohm / 50 pF
• Negative feedback: 5 dB or 1.8 dB
• Valve complement: 2 x ECC82 (12AU7)
  2 x EL34 (6CA7)
• Power consumption: 85 watt
• Fuses: T2A from 100V to 130V
  T1A from 220V to 240V
• Dimensions (mm.): 26 cm x 35 cm x H. 19cm
• Net weight: 15kg