Unison Research Simply 845 Integrated Valve Amplifier at Vinyl Sound Buffalo, NY USA

The Simply 845 is a Class A single-ended integrated valve amplifier from Unison Research (Treviso, Italy), available at Vinyl Sound in Buffalo, NY, USA. Sitting at the top of Unison Research's Simply series, the Simply 845 deploys the same 845 directly-heated triode as the company's legendary ABSOLUTE 845, in a more accessible single-chassis integrated configuration. Two 845 triodes operate in self-biasing single-ended Class A alongside four selected ECC82 tubes in the preamplifier stage, producing 23 watts per channel with a bandwidth of 20 Hz to 50 kHz at -1 dB. Hand-wound in-house output transformers using Mylar and polypropylene insulators, a motorized ALPS RK27 volume potentiometer, and triple-thickness copper PCB traces reflect Unison Research's commitment to component quality at every level of the signal chain.

The 845 Triode in a Single Chassis

The 845 directly-heated triode was designed for broadcast transmitter applications and repurposed for audio by Unison Research, among other pioneering firms, in the early 1990s. In the Simply 845, two 845 tubes operate in self-biasing mode -- requiring no manual bias adjustment by the user -- in a single-ended Class A output stage. The self-biasing circuit monitors and maintains each 845's operating point automatically as the tubes age, ensuring consistent performance over the tube's lifespan without the need for periodic bias measurement. The preamplifier stage employs four ECC82/12AU7 tubes operating in pure Class A, fed by a stabilized linear electronic power supply designed specifically to reject mains-borne noise before it reaches the audio signal.

Hand-Wound Transformers and Premium Circuit Components

Unison Research regards the output transformer as the single most critical component in a valve amplifier design. The Simply 845's output transformers are wound by hand in-house at the Treviso factory using very thin Mylar and polypropylene dielectric insulators, chosen to minimize parasitic capacitance and magnetic flux dispersion. The core material is a special iron-silicon alloy laminated in very thin layers with each lamination electrically insulated from its neighbors, a construction that aligns molecular domains to facilitate low-reluctance magnetic field propagation and reduces eddy current losses at high frequencies. All signal-path capacitors use polypropylene dielectrics in anti-inductive construction. PCB traces are pure electrolytic copper at three times the standard industrial thickness, reducing series resistance in the signal path. Volume control uses the motorized ALPS RK27 potentiometer -- a precision Japanese component specified for its channel matching and audio-grade tracking law.

Key Features

• Two 845 Self-Biasing Triodes: The 845 directly-heated triode operates in automatic self-bias mode, requiring no user adjustment as tubes age, and delivers 23 watts per channel in single-ended Class A.
• Pure Class A Throughout: Both preamplifier and output stages operate in pure Class A, eliminating crossover distortion at every gain stage.
• Hand-Wound In-House Output Transformers: Mylar and polypropylene insulators, iron-silicon alloy laminated cores, and in-house winding ensure the transformers match the output stage's sonic requirements precisely.
• Triple-Thickness PCB Copper Traces: Three times the standard copper trace thickness on fiberglass-backed boards reduces signal path series resistance and improves current delivery consistency.
• Motorized ALPS RK27 Volume Control: Japanese precision audio-grade potentiometer for accurate channel balance and smooth tracking.
• Anti-Inductive Polypropylene Capacitors: All signal-path capacitors use polypropylene dielectrics in anti-inductive construction for minimal capacitive reactance in the audio band.
• Four Line Inputs plus Subwoofer Output: Four RCA line inputs and a dedicated subwoofer output for integration with a low-frequency supplement system.
• Tube Cage Included: A protective tube cage is supplied as standard, given the substantial heat output of the 845 triodes during operation.

Technical Specifications

Frequently Asked Questions

What is the Unison Research Simply 845?

The Unison Research Simply 845 is a Class A single-ended integrated valve amplifier from Treviso, Italy, producing 23 watts per channel through two 845 self-biasing directly-heated triodes with four ECC82 preamplifier tubes. Its bandwidth extends from 20 Hz to 50 kHz at -1 dB and it features hand-wound in-house output transformers, four RCA line inputs, and a subwoofer output. It is the top model in Unison Research's Simply series.

How does the Simply 845 compare to the Unison Research ABSOLUTE 845?

The Simply 845 uses two 845 tubes to produce 23 watts per channel in a single-chassis integrated design. The ABSOLUTE 845 uses four 845 tubes in a dual mono stereo configuration to produce 40 watts per channel and includes five line inputs plus two tape loops -- a considerably more comprehensive connectivity specification. The ABSOLUTE 845 is approximately six times heavier (199 lbs vs 30.5 kg), reflecting its dual mono power supply and dual output transformer topology. The Simply 845 is the more accessible entry into 845 triode amplification from Unison Research; the ABSOLUTE 845 is the reference-level statement in the integrated amplifier category.

What does "self-biasing" mean for the 845 tubes in the Simply 845?

Self-biasing (also called cathode biasing or autobiasing) means that the operating point of each 845 tube is established by a resistor in its cathode circuit rather than by a fixed external voltage applied to its grid. As the tube ages and its transconductance changes, the cathode resistor automatically adjusts the effective bias current, maintaining the tube's operating point within an acceptable range without user intervention. In practice, this means the Simply 845 does not require periodic bias adjustment with a meter, which simplifies ownership compared to fixed-bias amplifiers.

Why does the Simply 845 include a tube cage?

The 845 triode tube measures nearly 8 inches from base pins to top and operates at very high plate voltages and temperatures during normal use. The included tube cage is a safety accessory that protects against accidental contact with the exposed glass envelope of the tubes during operation. Unison Research strongly recommends using the cage, particularly in households with children or pets, or in any environment where the amplifier may be touched accidentally during listening sessions.

What loudspeakers are recommended for use with the Simply 845?

At 23 watts per channel, the Simply 845 pairs optimally with loudspeakers of 90 dB sensitivity or higher. The Unison Research MAX 2 (96 dB), MAX 1 (94 dB), and MAX MINI (93 dB) are all natural partners within the brand range. High-sensitivity loudspeakers from DeVore Fidelity, Zu Audio, Klipsch Heritage series (La Scala, Klipschorn, Cornwall), and similar high-efficiency designs also pair exceptionally well. The 6-ohm output impedance is best matched to 8-ohm loudspeakers for optimal damping and power transfer.

Where can I buy the Unison Research Simply 845 in Buffalo, NY or the USA?

The Unison Research Simply 845 integrated amplifier is available at Vinyl Sound in Buffalo, NY, USA. Vinyl Sound is an authorized Unison Research dealer serving western New York and the United States. Contact Vinyl Sound for current availability and to schedule an in-store demonstration.