Q-tron Audio PA3B 2x8W Push-Pull Tube OTL Power Amplifier

The Q-tron PA3B is a high-end tube amplifier that achieves "over 10 times lower distortion" compared to other OTL (Output Transformer Less) amps thanks to its unique driver circuit. With its completely transformerless OTL design, it dramatically improves sound clarity, density, and speed. It reproduces a sound that retains the warm, supple texture of a tube amplifier while offering contemporary precision.
Each channel is equipped with two 6C41C tubes, and its unique driver stage ensures 8W output. The distortion rate at 0.5W is just 0.01%, and with the adoption of active noise reduction technology, hum and noise are kept extremely low. This amplifier offers high quietness, allowing the delicate nuances to emerge beautifully even at low volumes.

Optimized for modern use from the Futterman-style circuit—achieving both transparency and control

The PA3B uses a Futterman-style circuit optimized by Q-tron with modern components and analysis techniques.
The Futterman method is a transformerless OTL configuration that drives speakers directly and is known for wide bandwidth and excellent linearity.
Q-tron has added its own balance adjustments and stabilization techniques to this traditional design, delivering unwavering driving power against speaker load while maintaining high transparency.
It uses the same chassis size as the PA12, inheriting the PA12's expansive soundstage and powerful expression, while offering the soft, dense tonal character unique to 6C41C tubes.

Nordic craftsmanship for structural beauty and reliability

The main circuits are arranged on a high-quality PCB, with critical points for sound quality assembled point-to-point (PtP) by skilled technicians.
Ceramic solder supports capable of withstanding up to 5kV, along with a 10mm-thick aluminum chassis, thoroughly eliminate unnecessary vibrations and micro-noises.
All parts and assembly are made in Sweden and designed for durability and long-term stability.

Advanced auto bias adjustment - designed to always maintain optimal sound

Microprocessor-controlled auto-bias function automatically adjusts optimal bias and offset during operation.
Calibration works just before the amplifier stops, and the next time it starts up, it will start in ideal conditions.
It is automatically optimized when replacing vacuum tubes, eliminating the hassle of manual adjustment.

Dense and relaxed sound image - OTL power amplifier that inherits the ability inherited from PA12

PA3B is a model that combines the rich expression of a vacuum tube amplifier with the transparency and instantaneous power unique to the OTL system.
A spacious sound field, beautiful mid-high range, and tight low range harmonize naturally, expressing the essence of music as it is.

Overwhelming clarity and speed

• Like an OTL amplifier, it has an overwhelming "direct feel" without passing through an output transformer. There is really little turbidity in the signal, and the clarity of the mid-high range is outstanding. The sound comes through easily, and the response is quick. Even the smallest nuances could be heard clearly, and I was strongly impressed by the combination of speed and clarity that made this the OTL.

Rich musicality and beauty of harmonics

• smalloutput tubeThe beautiful overtones that are unique to this instrument are clearly present, and the sound has a natural warmth and density. Although it is clear, it is not cold, and the clarity and rich sound typical of vacuum tubes are perfectly balanced. It has an impressive "musical comfort" that makes you want to listen to it for a long time, and its appeal is especially noticeable in vocal and acoustic songs.

Ultimate localization and phase characteristics

• Thanks to the excellent phase characteristics provided by the OTL structure, the focus of the sound image is really sharp. The localization of instruments and vocals is determined clearly and clearly, and the depth and layers of the sound field can be clearly understood. For those who place importance on delicate localization expressions, I felt this would be a powerful feature.

Tight and agile low range

• The low range is not the type that produces a flashy volume, but it has a tight, agile, and sharp sound. It goes well with high-efficiency speakers, and the rhythmic increments are very clear. Each note responds quickly, and the crisp low range acts as the driving force of the music.