Unison Research
Sinfonia Integrated Tube Amplifier
Since 1987, Italian manufacturer Unison Research has brought
great listening pleasure to those passionate about music with its fine hifi
components. Over the years, the company continued advancing and evolving its
product designs with the goal of achieving the highest level of sonic
performance. From the early days, the designers at Unison Research had a strong
belief in exemplary integrated amplifier designs and today that tradition is
still at the heart of the company. The company believes that by focusing on
integrated amplifier designs, it is able to attain a higher quality of sound
since they require less cabling than separate components, which significantly
reduces of the effect of cable impedance on timbre and dynamics. Plus
integrated designs cost less to implement and therefore translate into savings
for music listeners. Today, Unison Research offers an extensive range of
amplifiers, preamplifiers and integrated amplifiers based on vacuum tube, solid
state and hybrid designs. There are also a couple of phono stages, the Giro
turntable and the Malibran loudspeakers within its portfolio of products. My
first personal experience with Unison Research was in 2012 when I evaluated the
company’s entry level integrated tube amplifier simply named... Simply Italy
($2,700). This turned out to be a rather revelatory musical experience and I
quickly fell in love with the sound of this little integrated amplifier. It
also made me wonder how much better the company’s larger, more expensive tube
amplifiers would sound. My curiosity was answered when I finally had a chance
to spend a few months listening to the Unison Research Sinfonia integrated tube
amplifier ($6,200) earlier this year.
My first personal
experience with Unison Research was in 2012 when I evaluated the company’s
entry level integrated tube amplifier simply named... Simply Italy ($2,700)
Unlike the compact-sized Simply Italy, the Sinfonia is a
full width component, demanding the top position an audio rack. It measures 44
x 42 x 21 cm and weighs a hefty 55 lbs. Its exterior features many of the same
styling cues that I enjoyed dearly about the Simply Italy, from the fine wood
work to the stainless steel top plate and control knobs, to the flat black
metal casework. The build quality and finish is absolutely perfect. But that’s
where the similarities end between these two integrated amps. The Sinfonia is
actually much closer in design to the Performance integrated amp model
($13,000), which is just one spot shy of the top-of-the-line Absolute 845 model
($43,890).
From the outside,
the Sinfonia may appear to be a traditional tube amplifier but from a design
standpoint, it is a highly advanced instrument
Offering a power output of 25 watts per channel, the
Sinfonia features a dual-mono configuration, meaning that each of its two
channels is fully independent. This design prevents all electrical and
electronic interference between the two channels. All of the amplification
stages are powered by valves, all operating in pure Class A. The onboard output
transformers are designed and built in house by Unison Research, since valve
amplifier performance is closely related to these complex devices. A specific
design element of the output transformers has enabled the Sinfonia ‘s power
stage to use two KT88 valves per channel in a single-ended parallel ultralinear
configuration, allowing the KT88 (beam power tetrodes) to operate like an ideal
triode. This allows the Sinfonia to achieve a higher power output and excellent
sound quality. However it also means that the KT88 valve pairs have to be very
carefully matched. As tube amplifier fans know, the characteristics of valves
change over time in a non-uniform manner due to an effect called the drift
phenomena. Unison Research has designed a unique circuit to address this issue,
which compensates the parameters affected by the drift in real time. This
solution allows the Sinfonia to offer the very best sound quality for many
years. It also slightly reduces the amount of warm up time. The
pre-amplification and the power stage drive utilize ECC83 and ECC82 triodes.
These parallel triodes are automatically biased, and offer amazing linearity
and an almost complete absence of odd order harmonic distortion. Unlike some
amplifiers that have a cheap volume control, the Sinfonia is equipped with a
high quality analog ALPS RK27 stereo motorized potentiometer, which offers a
smooth and precise operation. To learn about even more of the technical design
details of the Sinfonia, I recommend checking out www.unisonresearch.com.
Visually, the Sinfonia is a traditionally styled but very attractive integrated
amplifier. The wooden front plate is adorned with four stainless steel control
knobs - for power, volume, source selection and source/monitor selection. Four
green LEDs in the middle identify the currently selected music source. Just
above them is a small round window exposing the infrared remote sensor and
above that is the ‘Sinfonia’ logo. The top middle of the front plate is
decorated with a brushed gold/silver Unison Research emblem. The rear panel of
the Sinfonia is outfitted outfitted with high quality 4 and 8 ohm bi-amp
speaker taps, as well as four pairs of RCA inputs (Tuner, AV, CD and Phono).
There is also a ‘Sub Out’ for those wishing to supplement the bass output with
a subwoofer, and tape input and output jacks. The supplied remote control is
the same as the one that comes with the Simply Italy integrated amplifier and
although its combination of wood and brushed steel looks attractive, I’m not a
fan of its small, rough feeling buttons that all look the same and lack a sense
of good arrangement.
