Fezz Audio Lybra 300B Evolution Integrated Amplifier, designed for the most demanding enthusiasts of 300B tube sound. With PSE class A structure and high-quality toroidal transformers, it ensures linearity and wide frequency response. Features include 2x15W max output power, 4Ω/8Ω output impedance, and 3xRCA inputs. The unique tone of the 300B tubes is free, spacious, and very involving.
High-End 300B Class A Tube Amplifier | Parallel Single-Ended Design | 2 x 15W | Toroidal Transformers | Automatic Bias
The Fezz Audio Lybra 300B Evolution Integrated Amplifier is a high-end Class A vacuum tube amplifier developed for discerning music enthusiasts who appreciate the unique musical qualities of the legendary 300B directly heated triode.
Featuring a sophisticated Parallel Single-Ended (PSE) output architecture and custom-designed toroidal transformers, the Lybra Evolution combines the tonal beauty traditionally associated with 300B amplification with the increased power available from a parallel tube configuration.
Delivering 2 x 15 watts, the amplifier uses four 300B power tubes, two 6SN7 driver tubes and one 12AX7 preamplifier tube, supported by an automatic bias system.
Manufactured by Fezz Audio in Poland, Lybra 300B Evolution is designed to offer natural tonal expression, an expansive soundstage and an intimate connection with the musical performance.
Available through Chameleon Audio, the Fezz Lybra 300B Evolution is an excellent choice for audiophiles building a carefully matched high-end stereo system around Class A triode amplification.
The Musical Character of the 300B Triode
The 300B is one of the most respected directly heated power triodes in the history of high-fidelity audio reproduction.
Originally developed for professional electronic applications, the 300B became especially popular in specialist single-ended audio amplifiers because of its distinctive operating characteristics.
Many music enthusiasts value 300B amplification for its expressive midrange, natural vocal textures and sense of musical flow.
The Fezz Audio Lybra Evolution builds on these characteristics with a circuit specifically designed around four 300B output tubes.
Its sound is described by the manufacturer as spacious, involving and exceptionally expressive, with an emphasis on the natural character of acoustic instruments and voices.
Parallel Single-Ended Class A Amplification
At the heart of the Fezz Lybra 300B Evolution is a Parallel Single-Ended output circuit operating in Class A.
Unlike a conventional single-ended amplifier using one output tube per channel, the Lybra employs two 300B power triodes in parallel for each stereo channel.
This configuration allows Fezz to achieve a maximum rated output of 15 watts per channel while retaining the fundamental characteristics of single-ended triode amplification.
Parallel Single-Ended topology is particularly attractive to listeners seeking greater output capability without moving to a conventional push-pull circuit.
The result is a distinctive amplifier architecture that combines the musical character of the 300B with enhanced system flexibility.
Four 300B Directly Heated Triodes
The Lybra Evolution uses four 300B output tubes, arranged as two parallel pairs.
Each stereo channel benefits from its own pair of directly heated power triodes.
The amplifier also incorporates two 6SN7 valves and one 12AX7/ECC83 tube in its preceding amplification and driver stages.
The complete vacuum tube complement is:
4 x 300B: Power output tubes
2 x 6SN7: Driver tubes
1 x 12AX7 / ECC83: Small-signal amplification
The manufacturer also offers compatible premium tube options, depending on product configuration and availability.
Custom-Designed Toroidal Output Transformers
Transformer engineering is central to the performance of a single-ended vacuum tube amplifier.
The Fezz Audio Lybra 300B Evolution Integrated Amplifier uses high-quality toroidal output transformers designed specifically for its Parallel Single-Ended circuit.
Fezz draws on the transformer expertise associated with Toroidy, the Polish specialist whose technology plays an important role in the company’s amplifier designs.
The output transformers are engineered to provide appropriate impedance matching between the 300B output stage and compatible loudspeakers.
The manufacturer’s published frequency response of 12Hz to 60kHz (-3dB) illustrates the bandwidth achieved by the complete amplifier design.
Transformer design, magnetic core characteristics and winding construction are particularly important in achieving controlled low-frequency and high-frequency performance in single-ended amplifiers.
Evolution Series Power Supply Improvements
The Lybra 300B Evolution features a revised power supply incorporating a more powerful main transformer compared with the earlier design.
A carefully engineered power supply is essential for maintaining the operating conditions required by Class A vacuum tube circuits.
Fezz developed the Evolution platform with attention to power delivery, mechanical construction and long-term operational consistency.
The amplifier also incorporates anti-vibration feet adapted to the weight of the chassis.
Delayed Anode Voltage Activation
The Lybra Evolution incorporates a delayed anode voltage switching system.
This feature allows the tubes to undergo an appropriate initial warm-up period before the high anode voltage is applied.
The delayed activation process is designed to protect the vacuum tubes during startup and support their service life.
This is a useful convenience for owners who want the qualities of directly heated triodes combined with carefully engineered modern operating functions.
Automatic Bias Control
The Fezz Lybra 300B Evolution includes automatic bias adjustment.
The system manages the operating bias of the output tubes without requiring routine manual user adjustment.
Automatic bias simplifies everyday ownership and supports consistent operation within the manufacturer’s specified tube configuration.
Any replacement output tubes should be of an approved type and installed according to the Fezz Audio instructions.
15 Watts per Channel: Choosing the Right Loudspeakers
The Lybra Evolution produces 15 watts per channel, making loudspeaker matching particularly important.
For many listeners, amplifier power alone does not determine the listening experience. Loudspeaker sensitivity, impedance behaviour, room size and listening distance are equally relevant.
The Lybra is particularly suitable for consideration with efficient loudspeakers that can achieve the desired listening levels from a moderate amplifier output.
Its dedicated 4-ohm and 8-ohm speaker connections allow appropriate matching with loudspeakers within the manufacturer’s supported impedance ranges.
For very inefficient or electrically demanding loudspeakers, a higher-power amplifier may be the more suitable choice.
Chameleon Audio can advise on suitable loudspeaker matching before purchase.
Ideal for Vocals, Jazz, Acoustic and Classical Music
The musical appeal of the Fezz Lybra 300B Evolution is particularly relevant to listeners who appreciate natural tone and expressive detail.
The manufacturer’s presentation emphasises openness, spatial character and a highly involving listening experience.
With compatible loudspeakers, its single-ended triode architecture makes it an interesting option for vocal recordings, acoustic instruments, chamber music, jazz ensembles and classical performances.
These are listening characteristics rather than guaranteed outcomes, since the complete system and listening environment influence the final result.
Three Analogue RCA Inputs
The Lybra 300B Evolution provides three stereo RCA line-level inputs.
These connections can accommodate compatible audio sources including:
High-end CD players
Digital-to-analogue converters
Network music streamers with analogue outputs
External phono preamplifiers
For vinyl playback, a separate phono stage is required unless the connected turntable or associated source already provides suitable line-level output.
The amplifier does not include a dedicated phono input as standard.
Optional System Integration Features
Fezz Audio offers several optional features for the Lybra 300B Evolution, depending on the selected configuration.
These may include:
Remote volume control
Protective tube cage
HT / preamplifier input
Bluetooth module
Subwoofer pre-output
Premium vacuum tube set
Optional features are not necessarily included in the standard amplifier price.
Availability should be confirmed with Chameleon Audio before ordering.
Optional HT Input
When specified with the appropriate optional HT input, the Lybra Evolution can be integrated into compatible external preamplifier or home theatre systems.
This input arrangement should only be used according to the manufacturer’s instructions and with appropriate upstream volume control.
Optional Subwoofer Output
An optional subwoofer pre-output can provide additional system flexibility when using a compatible active subwoofer.
Successful integration requires suitable adjustment of subwoofer level, crossover frequency and phase.
Elegant Evolution Series Construction
The Fezz Lybra Evolution combines exposed vacuum tubes, carefully engineered internal transformers and the clean industrial design of the Evolution Series.
Its substantial chassis weighs approximately 23.5kg, reflecting the mechanical construction and transformer assemblies required by its Class A design.
The amplifier measures 420 x 380 x 226mm with the tubes installed.
Its available finishes allow the amplifier to complement a variety of high-end listening environments.
As with all exposed-tube amplifiers, adequate ventilation and sufficient clearance around the valves are essential during operation.
Fezz Lybra Evolution vs Conventional Single-Ended 300B Amplifiers
A conventional stereo single-ended 300B amplifier normally uses one 300B output tube per channel.
The Lybra Evolution instead uses two 300B tubes in parallel per channel, creating its Parallel Single-Ended architecture.
This arrangement provides a rated output of 2 x 15 watts while maintaining Class A single-ended operation.
The Lybra therefore offers an alternative for music enthusiasts who appreciate 300B amplification but require more output power than certain lower-powered single-ended designs provide.
Technical specifications refer to the Fezz Audio Lybra 300B Evolution. Optional equipment and finishes depend on the selected product configuration.
Download the Fezz Lybra 300B Evolution User Manual
For safe installation, correct tube placement, speaker connections and operating instructions, download the Lybra 300B Evolution User’s Manual.
Why Buy from Chameleon Audio?
At Chameleon Audio, we specialise in high-end audio equipment, carefully selected vacuum tube amplifiers and personalised system-matching advice for music enthusiasts worldwide.
Free Worldwide Shipping with Full Transport Insurance
All brand-new products purchased from Chameleon Audio include FREE SHIPPING WITH FULL TRANSPORT INSURANCE.
Your new amplifier is carefully packed and insured during transportation for additional peace of mind.
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The Lybra Evolution is a high-end Class A stereo integrated amplifier using four 300B output tubes in a Parallel Single-Ended configuration.
How much power does the Lybra 300B Evolution deliver?
The amplifier provides a maximum rated output of 15 watts per channel.
What does Parallel Single-Ended mean?
Parallel Single-Ended describes an output circuit in which multiple power tubes operate together within each single-ended channel. The Lybra uses two 300B output tubes per channel.
How many 300B tubes does the amplifier use?
The Lybra uses four 300B power triodes, along with two 6SN7 driver tubes and one 12AX7 small-signal valve.
Does the Lybra operate in Class A?
Yes. Fezz specifies Class A operation with Parallel Single-Ended circuit architecture.
Does the Lybra require manual bias adjustment?
No routine manual bias adjustment is required because the amplifier features automatic bias control.
Does it have a tube warm-up protection system?
Yes. Delayed anode voltage activation helps manage the startup process and protects the tubes.
Can the Lybra drive 4-ohm or 8-ohm loudspeakers?
Yes. The amplifier provides connections for compatible 4Ω and 8Ω loudspeakers. Sensitivity and impedance behaviour should be considered when matching a 15W amplifier.
Is the Lybra suitable for low-sensitivity speakers?
It depends on the speakers, listening distance, room size and required volume. More efficient loudspeakers are generally a better starting point for a 15W Class A amplifier.
Does the Lybra have a built-in phono stage?
No dedicated phono input is specified as standard. A separate compatible phono preamplifier is required when connecting a conventional turntable cartridge.
Can I connect a DAC or network streamer?
Yes. A compatible DAC, CD player or streamer with analogue line outputs can connect to one of the three RCA inputs.
Does it include remote control?
Remote control is listed among the optional features and should be confirmed for the selected configuration.
Can I add Bluetooth?
Fezz lists Bluetooth functionality as an optional feature on compatible Lybra Evolution configurations.
Can I connect an active subwoofer?
An optional subwoofer output may be available. Confirm that the selected amplifier configuration includes this feature.
How heavy is the Fezz Lybra 300B Evolution?
The published net weight is approximately 23.5kg.
Where can I buy the Fezz Lybra 300B Evolution?
The amplifier is offered through Chameleon Audio with specialist advice on loudspeaker matching, optional equipment and international ordering.
Explore High-End Tube Amplifiers at Chameleon Audio
Fezz Audio Lybra 300B Evolution at Chameleon Audio
The Fezz Audio Lybra 300B Evolution Integrated Amplifier combines four legendary directly heated 300B triodes, Class A Parallel Single-Ended amplification and custom-designed toroidal transformers in a distinctive high-end stereo component.
Its 15 watts per channel, automatic bias system, delayed anode voltage activation and optional connectivity features make it a compelling choice for enthusiasts of expressive vacuum tube amplification.
Contact Chameleon Audio for Fezz Lybra 300B Evolution availability, available finishes, optional upgrades, loudspeaker matching and worldwide delivery information.
Specifications
Type:
Stereo vacuum tube amplifier
Model:
Lybra
Max. output power:
2x15W
Circuit type:
PSE parallel single ended
Output impedance:
4Ω/8Ω
Inputs:
3xRCA
Harmonic distortions THD:
<0,25%
Frequency response:
12Hz-60kHz (-3dB)
Power consumption:
180W
AC fuse:
3,15A T
Net weight:
23,5 kg
Dimensions:
420x380x226 mm
Tubes:
4x 300B, 2x 6sn7, 1x 12AX7, autobias
Colours:
black, white, burgundy, red
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