Glossary for Unison Research Amplifiers
Welcome to our comprehensive glossary of terms related to Unison Research amplifiers. This resource is designed to help audio enthusiasts, both newcomers and experienced audiophiles, navigate the specialized terminology associated with Unison Research's renowned tube amplifiers and audio equipment.
Founded in Italy in 1987, Unison Research has established itself as a premier manufacturer of high-quality valve amplifiers known for their exceptional sound quality, innovative design, and meticulous craftsmanship. This glossary covers technical specifications, proprietary technologies, audio terminology, and design elements specific to Unison Research products.
Whether you're researching your first Unison Research purchase or looking to deepen your understanding of your existing equipment, we hope this glossary serves as a valuable reference in your audio journey.
A • B • C • D • E • F • G •H • I • J • K • L • M • N • O • P • Q • R • S • T • U • V • W • X • Y • Z
Amplifier Classes (A, B, AB, C, D, E)
Design classifications that describe how amplifiers operate and their efficiency. For example, Class A amplifiers conduct output transistors throughout the entire input cycle, offering high fidelity but lower efficiency, while Class D amplifiers use switching technology for higher efficiency.
Anode
The positively charged electrode by which electrons leave a device. In a vacuum tube, the anode collects electrons emitted by the cathode.
B
Bandwidth
The range of frequencies an amplifier can process without significant loss of signal.
Biasing
The process of setting a transistor's or tube's operating point to ensure optimal performance.
Bypass Input (AV Bypass)
A direct input that allows integration with AV receivers for home theater setups (found in Simply Italy).
C
Cathode
The negatively charged electrode by which electrons enter a device. In a vacuum tube, the cathode emits electrons.
Clipping
A form of distortion that occurs when an amplifier is overdriven and attempts to deliver an output voltage or current beyond its maximum capability, resulting in a "clipped" waveform.
Chassis Resonance Control
Design aspects minimizing vibration and interference within the amplifier enclosure.
D
Distortion
Any alteration of an audio signal that degrades the sound quality.
Dynamic Range
The difference between the quietest and loudest parts of an audio signal that an amplifier can handle without distortion.
DAC Input
Digital-to-analog converter input; available in select models (optional or built-in for Unico Due).
E
ECC82 (12AU7)
A specific type of vacuum tube featuring two triode units in one envelope, commonly used in the input stages of Unison Research amplifiers for voltage amplification.
EL34
A classic power vacuum tube known for musical warmth and smooth midrange.
Efficiency
The ratio of useful power output to total power input, expressed as a percentage. Higher efficiency means less energy is wasted as heat.
F
Feedback
A portion of the output signal that is returned to the input to control the gain and linearity of an amplifier.
Frequency Response
The range of frequencies over which an amplifier can operate effectively, typically measured from the lowest to the highest frequency it can reproduce.
Front Panel Selector
Switches for input selection and volume, often minimal for aesthetic and sonic purity.
G
Gain
The ratio of output signal strength to input signal strength, indicating how much an amplifier increases the signal's amplitude.
Grid
In a vacuum tube, the electrode that controls the flow of electrons between the cathode and anode, effectively regulating the amplification process.
H
Harmonic Distortion
The presence of harmonics in the output signal that were not present in the original input signal, leading to a change in the sound's character.
Headroom
The amount by which an amplifier can exceed its nominal operating level without distortion. More headroom allows for better handling of transient peaks in audio signals.
Hexfet
A high-performance type of MOSFET used in the power stages of hybrid Unison Research amplifiers (e.g., Unico series).
I
Impedance
The resistance of an electrical circuit to the flow of alternating current, measured in ohms (Ω). Matching the impedance of speakers and amplifiers is crucial for optimal performance.
Input Sensitivity
The minimum input signal required to drive an amplifier to its full output.
Combines a preamp and power amp in one unit. All Unison Research models listed on our website are integrated amplifiers.
J
Jack
A socket or port on an amplifier used to connect input or output devices, such as instruments or speakers.
K
Kilohertz (kHz)
A unit of frequency equal to 1,000 hertz. Audio frequencies are often measured in kilohertz.
L
Line Level
The standard signal level used by audio equipment for transmitting audio signals between components, typically around 1 volt.
Line Inputs
RCA connections for external sources like CD players, streamers, or DACs.
Load
The component or device that consumes power from an amplifier, typically a speaker or set of speakers.
M
MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor)
A type of transistor used in amplifiers for its efficiency and thermal stability, often employed in the output stages of Unison Research's hybrid designs.
Monoblock Amplifier
An amplifier design where each unit amplifies a single audio channel, often used in high-end audio systems for improved channel separation and performance.
N
Negative Feedback
A technique where a portion of the output signal is inverted and fed back to the input to reduce distortion and improve stability.
Noise Floor
The level of background noise in an amplifier, below which the audio signal cannot be distinguished. A lower noise floor indicates a cleaner amplifier.
O
Ohm (Ω)
The unit of electrical resistance or impedance. Amplifiers and speakers are rated in ohms to indicate compatibility.
Output Transformer
A component in tube amplifiers that matches the high impedance of the tubes to the lower impedance of speakers, ensuring efficient power transfer.
P
Power Output
The amount of power, typically measured in watts, that an amplifier can deliver to the speakers.
Pre-Amplifier (Preamp)
An electronic amplifier that prepares a small electrical signal for further amplification or processing, often used to boost signals from audio sources to line level.
Phono Stage
Built-in or optional input to connect turntables (e.g., Unico Due supports MM/MC cartridges).
Q
Quiescent Current
The small amount of current that flows through an amplifier's output transistors when there is no input signal, important for setting the operating point in Class A and AB amplifiers.
R
RMS (Root Mean Square)
A statistical measure of the effective value of a varying signal, used to denote continuous power output of an amplifier.
Resistor
An electronic component that resists the flow of electric current, used in amplifiers to control voltage and current levels.
Remote Control
All current models include remote functionality for volume and input switching.
RCA Input/Output
Standard analog audio connection used on all Unison integrated amps
S
Single-Ended Triode (SET)
Amplification topology known for ultra-pure midrange, used in models like Simply Italy.
“Super-Symmetric” configuration
A high-performance circuit topology used in amplifier design to reduce distortion and improve signal purity.
T
Transformer-Coupled Output
Essential to all-tube designs, ensures signal integrity and power matching.
U
The Unison Research Simply Italy is a Class A integrated amplifier delivering 12W per channel into 8Ω. This minimalist design embodies audiophile-grade craftsmanship, utilizing vacuum tubes (valves) for its input stage to provide a smooth, rich, and highly detailed sound signature. With its small footprint, it is ideal for intimate listening spaces or pairing with high-efficiency speakers. The Simply Italy is perfect for those who appreciate the warmth and musicality of Class A amplification and tube technology.
The Unison Research Triode 25 is an integrated valve amplifier combining Class A and Class AB topologies to deliver 45W per channel into 8Ω. With a hybrid design, it features triode mode for the input stage with ECC83 valves and a Class AB output stage, offering a dynamic and engaging sound with both warmth and power. The Triode 25 is suited for audiophiles who want a balance between Class A’s richness and Class AB’s efficiency.
The Unison Research Preludio is a pure Class A tube amplifier, offering 14W per channel into 8Ω. Known for its musicality, it features ECC83 valves in the input stage, providing an exceptionally clean and natural sound. With a simplicity-driven design, the Preludio delivers warmth and an immersive audio experience ideal for smaller, high-sensitivity speakers. Whether you're playing vinyl or digital sources, the Preludio ensures a timeless, analog warmth that audiophiles love.
The Unison Research S6 is a pure Class A integrated amplifier delivering 35W per channel into 8Ω. This model is built for high-performance sound, featuring vacuum tubes in its input stage and a Class A output stage. The S6 offers deep, detailed, and highly engaging audio with an emphasis on midrange warmth and musical clarity. It’s the perfect amplifier for audiophiles who want to enjoy high-fidelity sound in a more powerful, pure Class A design.
The Unison Research Sinfonia is a pure Class A integrated valve amplifier offering 25W per channel into 8Ω. Designed for audio purists, it uses vacuum tubes in both the input stage and the output stage to provide a smooth, musical sound with rich tonalities. Its low power output makes it ideal for high-sensitivity speakers, delivering crystal-clear audio reproduction. The Sinfonia is perfect for those seeking a beautifully balanced, natural listening experience with a focus on tone richness and clarity.
An integrated amplifier delivering 95W per channel into 8Ω. It features a hybrid design with a pure Class A input stage utilizing two ECC83 (12AX7) valves and a dynamic Class A POWER MOSFET output stage. The Unico Nuovo offers five line-level RCA inputs (with an optional phono stage), a tape output, and a subwoofer output with volume control. Its frequency response ranges from -0.1dB at 10Hz to -0.5dB at 100kHz, ensuring detailed and accurate audio reproduction.
This hybrid integrated amplifier provides over 80W per channel into 8Ω. It combines a Class A triode input stage with a single ECC83 valve and a Class AB output stage featuring four POWER MOSFETs. The Unico Primo includes five line-level RCA inputs (one optionally configurable as a phono input), a tape output, and a subwoofer output. Its frequency response is -0.1dB at 10Hz and -0.5dB at 100kHz, offering a wide and balanced soundstage.
A hybrid integrated amplifier rated at 100W per channel into 8Ω and 160W per channel into 4Ω. The Unico 90 features a pure Class A input stage with a double triode totem pole configuration using ECC83 and ECC81 valves, directly driving a Class AB thermostable output stage with six complementary HEXFETs per channel. It offers multiple inputs and outputs, catering to various audio setups.
An integrated amplifier delivering 100W per channel into 8Ω, 180W into 4Ω, and 290W into 2Ω. It incorporates a dynamic Class A output stage with a double complementary pair of BJTs in a "Super-Symmetric" configuration. The input stage features two ECC83 (12AX7) valves operating in pure Class A. The Unico Due provides versatile connectivity options, including three analog line inputs, a USB digital input, a tape input, a phono input supporting both MM and MC cartridges, and outputs for tape, subwoofer, and DAC.
This high-end hybrid integrated amplifier delivers 150W per channel into 8Ω and 250W per channel into 4Ω. It features a three-stage design: a pure Class A input stage with double triode totem pole ECC83 valves, a driver stage with 6H30 valves, and a Class AB thermostable output stage with eight HEXFETs. The Unico 150 offers six line inputs (three unbalanced, two balanced, and one "bypass" unbalanced), along with tape and subwoofer outputs.Its frequency response is -1dB at 12Hz and 45kHz, ensuring a broad and detailed audio performance.
A line of hybrid amplifiers by Unison Research that blend tube input stages with solid-state output stages, aiming to provide the sonic benefits of tubes with the power and control of solid-state technology.
An Italian manufacturer founded in 1987, renowned for producing high-quality tube and hybrid amplifiers that combine technical expertise with elegant design.
USB DAC Module
Optional feature on models like Simply Italy for high-resolution digital audio playback.
V
A valve (or vacuum tube) amplifier uses vacuum tubes instead of transistors to amplify sound. Tube amps are revered for their warm, rich, and harmonically complex tonal character. All models on the Unison Research Tube Amplifier page are handcrafted Italian tube designs.
W
Wattage (WPC)
Power output in watts per channel, typically between 10W to 100W depending on the model.
X
XLR (Balanced Input)
Not commonly found on Unison Research integrated amps, which focus on purist RCA designs.
Y
Yugoslavian/European Tubes
Premium NOS tubes from Europe are often used for tube rolling with Unison amps.
Z
Zero Feedback Design
Avoids negative feedback for a more organic and open soundstage (used in Unico 90).