After the acclaim we have received from both audiophiles and the press for our Performance model, we have decided to design and produce a new, smaller valve integrated amplifier called the Sinfonia. The Sinfonia is very close to the Performance amplifier in both technical characteristics and appearance, but at a lower price.
Faithful to Unison.Research tradition, this new amplifier is also an integrated design. We feel that integration offers several advantages both in terms of simplicity of use and attainable sound quality. Since an integrated amplifier requires less cabling than its separate counterparts, this allows a substantial reduction of the effect of cable impedance on timbre and dynamics. In addition, there is a significant saving in production costs as well.
On the other hand, designing an integrated amplifier is a much more challenging task than designing a separate pre-power combination. For example, we have to carefully consider all the possible interferences between different components and different stages such as the power supply, control, pre-amplification and the output stage. Our experience in the design and production of integrated amplifiers has grown over the years, however, allowing us to create legendary products which are still classics today such as the widely renowned Absolute 845.
As we have mentioned, the new Sinfonia is smaller than the Performance and reaches an output power of 27-30W per channel. The new model is laid out in dual-mono configuration according to the traditions of high-quality amplification: within a single chassis there are two identical and fully independent amplifiers, a design that prevents any possible electrical or electronic interference between the two channels.
Each amplification stage is entrusted exclusively to valves, and all operate in pure Class A.
The Sinfonia, like the Performance, is characterized by the presence of two large heat sinks mounted on the sides. These are required by the high voltage stabilized power supply circuits, which are protected by a wide stainless steel cover. The cover material is non-magnetic and has low thermal conductivity; it prevents the heat generated by the four KT88 from reaching the circuits located below. This improves the stability of the amplifier, which in turns affects the sound quality and the overall reliability of the system.
Since its beginning, Unison Research has been directly involved in the designing, developing and building of the output transformers for our devices. We feel that valve amplifier performance is closely connected to the quality of these complex components. Thanks to a particular design feature of the output transformers, it has been possible to design a power stage for the Preludio that is made up of two KT88 per channel in single-ended parallel ultra-linear configuration, in which the KT88 (beam power tetrodes) operate with good approximation like an ideal triode.