Kronos AV

Unison Research Sinfonia Integrated Valve Amplifier
Free Gift

  • Sale
  • Regular price £4,250.00


Inspired by the highly acclaimed Performance amplifier, the Sinfonia is designed to be as close to the appearance and technical ability of the Performance while achieving a lower price-point. By making this an integrated design Unison Research have stayed true to their traditions, supporting the philosophy that integrated amplifiers can achieve a better sound by taking away the need for external cables, as cable impedances can negatively effect the timbre and dynamics of a hi-fi system's delivery.

The Sinfonia is a dual-mono design, which effectively eliminates the possibility of cross-channel electrical interference. Each amplification stage inside the Sinfonia is pure Class A and operates exclusively with valves. The amplifier is able to deliver a very capable 27-30W (max.) output power, per channel.

The Sinfonia, like the Performance, is accented by two large heat-sink "wings" 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 top-plate is non-magnetic stainless steel and has low thermal conductivity, so it prevents the heat generated by the four KT88 from reaching the circuits located inside. This improves the stability of the amplifier, which in turn enhances the sound quality and the overall reliability of the system.

Thanks to Unison Research's extensive knowledge of output transformer production, the Sinfonia has been designed with a power stage that is made up of two KT88 valves per-channel in single-ended parallel ultra-linear configuration, in which the KT88 (beam power tetrodes) operate, with good approximation, like an ideal triode. This configuration provides very good results in terms of sound quality, however the natural drawbacks of valves (namely the non-uniform decline in performance over time due to drift) need to be addressed. So, after much testing, Unison Research developed an an original circuit design which, through the control of the KT88 bias, ensures a real-time compensation of the parameters affected by drift. This solution guarantees the best sound quality even after many years, and also contributes to a slight reduction in the time it normally takes for the tubes to warm up after switching on and reach the optimal temperature.

The pre-amplification and the power stage drive are based on the double triodes ECC83 and ECC82. These valves guarantee excellent linearity and offer a nearly complete absence of odd-order harmonic distortion components. Both the stages are made up of triodes in parallel and are biased by automatic bias circuits. In this way the output impedance of the two circuits can be slightly reduced, which in turn improves the linearity of the stages. The signal-to-noise ratio and the total harmonic distortion improve significantly in this design as well. The direct current on the preamplifier valve filaments is supplied by an interesting circuit configuration: it works by directing the power stage valves cathode current through a parallel regulator which operates like a zener diode to the filament’s terminal.

With audio amplifiers, the anodic voltage should ideally be supplied by a battery, but this is obviously not possible for a number of practical reasons. So, to compensate, the Sinfonia employs a special anodic power supply circuit that features an output capacitance that is much higher than usual, emulating the performance of a battery supply.

The appearance of Sinfonia is both striking and functional. The control knobs are machined from solid, non-magnetic stainless steel and are weighted and balanced to provide a smooth, precise performance when used. The wooden parts, aside from their obvious visual beauty, effectively dampen out induced resonance in the metal chassis. Thanks to this structural damping, the valves themselves, which like all vacuum tube devices are susceptible to microphony, are much less liable to generate unwanted resonance-related effects. For the best reliability and long term musical quality, all the components used in the Sinfonia have been chosen with care from the non-inductive resistors and the filter capacitors, to the pure ceramic valve bases and the vetronite printed boards. The dimensions, distribution and lay out of the PCBs have been accurately studied and optimized to limit electrical disturbances and prevent components from overheating.

The supplied infra-red remote handset allows for convenient control over input switching and the premium motorised volume pot from ALPS. The back panel is finished with six gold-plated speaker terminal connectors that allow the connection of 4Ω and 8Ω loudspeakers, alongside clearly marked gold-plated RCA inputs for multiple audio sources. Next to the "Tape Out" connector is an additional low-impedance output terminal for connecting an active subwoofer; this terminal is linked to the pre-amplifier stage directly for reliable sub-performance. The source inputs have a buffer-stage to eliminate any negative effects connecting a subwoofer could have on the performance of the amplifier. The back-panel also has a power cable connector for upgrading the basic power supply included with the Simply Phono phono stage.

The Sinfonia is available with a premium cherry wood finish (mahogany wood finish is available to special order).

Key Features:

  • Dual mono Stereo Integrated Valve Amplifier
  • Single-ended Parallel Class A output stage
  • KT88 valves used in sophisticated output stage design
  • Based on the superior Performance amplifier
  • 27-30W output
  • Subwoofer output
  • 4Ω and 8Ω loudspeaker terminals
  • Simply Phono power supply upgrade built-in
  • RC2 remote included
  • High-quality Cherry Wood finish*

 

Unison Research Sinfonia, What Hi-Fi?, February 2006 February 2006

 

 

Type: Dual-Mono Stereo Integrated Valve Amplifier
Output Stage: Single-Ended Parallel Ultra-Linear Class A
Output Power: 25W
Inputs: 4 x Line
1 x Tape
Input Impedance: 47kΩ
Outputs: 1 x Tape
1 x Subwoofer
Loudspeakers (bi-wiring)
Output Impedance: 4 - 8Ω
Feedback Factor: 14dB
Frequency Response: 20 - 30,000Hz
Valves: 4 x 6550 / KT88
2 x ECC82
2 x ECC83
Remote Control: IR control of inputs and volume
Power Consumption: 500W (max.)
Dimensions: 44 x 21 x 42cm
Net Weight: 55lbs.
We have several deomonstation areas in both of our branches. Please give us a call on 03435236169 or email support@kronosav.com to enquire about hearing products at your local branch. 

Please always contact us before to make sure the product(s) are available

Express Deliveries

Express Delivery is FREE on all orders over £50. Express Delivery offers delivery in 24-72 hours from time of purchase. We use premium couriers for this service, mainly DPD & Royal Mail. DPD will offer you a one hour window for delivery to make sure someone is at home, or you can reschedule the delivery if no one is around. 

Standard Deliveries

Here at Kronos AV, we have vast experience with e-commerce sales. Making sure that your parcel arrives undamaged is a huge priority for us. That’s why at Kronos AV, we only use premium couriers for all our orders. All our parcels are shipped with DPD or Royal Mail and are always sent Signed For to make sure it gets to the right person. 

If for any reason your parcel does arrived damaged, please get in touch, and we will be happy to get everything resolved for you. We are always on hand to help!

Details

Delivery is FREE on all orders over £50. In order to offer FREE delivery to UK customers, we use several premium couriers to ensure your delivery arrives safe.

Most large orders (over 2kg) ship using DPD or DHL courier and smaller orders (under 2kg) by Royal Mail signed for services.

The most appropriate courier will be chosen for the items ordered to ensure the quickest possible delivery.

We can offer very generous trade in offers across the majority of our product range. 

Why not ask and see how much you HiFi is worth!

To find out how much your HiFi is worth... Click Here

If you have any question, please feel free to call us on 03435236169 or email support@kronosav.com