Unison Research Simply 845 - Audiophile Integrated Tube Amplifier

The New Simply 845 ranks at the top of Unison Research’s line of integrated tube amplifiers, second only to the historic ABSOLUTE 845. The SIMPLY 845, like the ABSOLUTE 845, also employs the famous 845 direct-heated triodes, tubes well known for remarkable durability and extraordinary sonic qualities.

The great advantage of integrated amplifiers is the incorporation in a single chassis of the preamplifier and the power amplifier. This makes it possible to eliminate the need for high-cost interconnect cables that are never truly neutral to sound reproduction. It should be noted that in the renewed production of the Simply 845 its size has been reduced by bringing all input and output connectors, strictly gold-plated and of a new type, to the rear of the amplifier.

Transformer

As in all Unison Research tube amplifiers, the output transformers in the Simply 845 are of our exclusive design and made one by one, by hand.

A good output transformer is not only the result of a rigorous design, but also the choice of materials particularly suited to act linearly with the intense magnetic and electric fields interacting within it.

The Simply 845 uses very thin Mylar and Polypropylene insulators suitable to contain parasitic capacitance and dispersion of magnetic fluxes as much as possible thus achieving an extended frequency range and very low harmonic distortion.

In addition, the ferromagnetic core employed is considerably different from cores commonly used in audio products and consists of a stack of thin laminations of a special alloy of iron and silicon all insulated from each other, the molecules of which are oriented and fixed in a stable manner to facilitate the flow of the lines of force of magnetic fields.

Circuits

In the Simply 845 all stages, both the preamplifier and power output, operate in pure class A. The preamplifier circuits are fed by stabilized linear-type electronic power supplies designed specifically to minimize interference with mains noise.

In the electronic circuits, all capacitors affected by the audio currents are anti-inductive with armatures insulated by polypropylene dielectrics, the ultimate in current technology. The printed circuit boards used are not of the normal industrial type, but differ in having fiberglass backing, and pure electrolytic copper traces three times as thick as the standard.

The volume potentiometer plays a very important role in high sound quality, and for this reason our choice fell on the famous RK27 motorized Japanese-made ALPS.

Specifications

• Type Integrated tube amplifier
• Tubes 2 x 845 selected, 4 x ECC82/12AU7 selected
• Class Pure class A
• Output stage topology Single-ended
• Maximum power 23W
• Bandwidth 20Hz-50kHz, +0dB; -1dB @ 12W
• Feedback level 14 dB
• Output impedance 6 Ω
• Input impedance 47 kΩ/100pF
• Inputs 4 line level
• Outputs 1 tape, 1 subwoofer
• Power consumption 300VA
• Sizes (Without packaging) 37 cm x 26cm x 57 cm (LxHxD) 14 1/2 x 10 1/4 x 22 1/2  inch
• Weight 30.5 kg – 67 Ibs
• Mains fuses 5x20mm – 3.15 AT, 220V-240V