Imagine a beautiful blonde girl with a bright smile, gently holding a vintage pear-shaped vacuum tube in her hands. A deliberately symbolic image, created to represent the passion for those magnificent vacuum tubes of the 1920s and 1930s, when elegant design, mechanical simplicity, and functionality blended together naturally. From this inspiration comes Pyrus, a single-ended tube amplifier that does not chase impressive specifications or modern trends, but instead celebrates the timeless charm of early vacuum tubes and the magic of a direct, pure, and uncompromised sound.
In the world of high fidelity, some amplifiers are built not only to reproduce music, but also to tell a story. Pyrus is one of them. A single-ended tube amplifier whose roots reach back to the pioneering era of electronics, when pear-shaped vacuum tubes represented the very best technology available, and just a few carefully engineered watts could deliver a rich, lively, and remarkably natural listening experience.
Pyrus: The Amplifier That Tells a Story
Pyrus is the natural evolution of the Pollitos, based on the legendary 71A tube. Once again, the project was commissioned by the same passionate enthusiast, deeply fascinated by ultra-low-power amplifiers and pre-war vacuum tubes. The goal was not simply to build “another amplifier,” but to travel even further back in time, exploring the sonic character of the type 46 tube, one of the true icons of the first generation of audio power tubes.
Pyrus is designed for attentive listeners, for owners of high-efficiency loudspeakers, and for those who understand that a single well-designed watt can deliver more emotion than dozens of anonymous ones. It is an amplifier that encourages you to slow down, to truly listen, and to rediscover the three-dimensional soundstage and natural tonal balance that only the simplest circuits can provide.
The Type 46: A Forgotten Audio Tube from the 1930s
The type 46 vacuum tube was introduced in the United States in 1933 and remains one of the most interesting and unconventional audio tubes of its time. It features a dual-grid structure and was designed with remarkable versatility. According to the original datasheet, it could operate in Class B with both grids connected together, or in Class A by connecting the outer grid directly to the plate, an unusually sophisticated solution even by the standards of that era.
It is no coincidence that engineers of the early 1930s considered the type 46 an advanced tube. As early as 1933 it was employed in the Silvertone 1654, a sophisticated 12-tube receiver featuring three type 46 tubes in the audio section, following a configuration recommended by the manufacturer itself: one type 46 operating in Class A as a driver feeding a push-pull pair of type 46 tubes operating in Class B.
Its construction is equally fascinating. The filament uses an oxide-coated ribbon design, while the grids are supported by copper structures to improve heat dissipation. Looking through the upper mica, the filament loops and the perfectly aligned grid wires are clearly visible, revealing the precision of early vacuum tube manufacturing. The classic pear-shaped bulb, approximately 51 mm in diameter and 118 mm tall excluding the UX5 base pins, further enhances its unmistakable vintage appearance.
Despite its modest power capability, the type 46 has earned a lasting reputation for its excellent linearity, refined sonic character, and remarkably forward-thinking design. These qualities continue to make it a highly desirable choice for today’s most purist single-ended amplifier projects.
Technical Specifications
- Configuration: Class A single-ended tube amplifier
- Output tubes: Type 46 directly heated triodes, renowned for their linearity and musical presentation
- Driver tube: Type 27, selected for its tonal consistency and excellent driving capability in minimalist circuits
- Output power: approximately 1.2 W RMS per channel, optimized for high-sensitivity loudspeakers
- Output transformers: SE6K4-46, specifically designed for the type 46 tube and premium single-ended applications
The design philosophy behind Pyrus is straightforward: simple circuitry, carefully selected components, and uncompromising attention to sonic performance. It is not an amplifier designed to impress through sheer power or exaggerated effects, but one that focuses entirely on naturalness, micro-dynamics, and the ability to reproduce the subtle breathing of music. Every design choice was made to let the tubes express their true character, avoiding unnecessary complexity while preserving their unique sonic personality.
For DIY Enthusiasts
Pyrus is also intended for those who enjoy building, understanding, and experimenting with audio equipment. A dedicated transformer kit is available for DIY enthusiasts, designed to ensure electrical compatibility, safety, and sound quality consistent with the original amplifier.
The kit includes:
- Complete schematic diagram
- One dedicated power transformer
- Two SE6K4-46 output transformers
- One filter choke
Pyrus is more than simply a tube amplifier. It is a tribute to the history of audio engineering, honoring the pear-shaped vacuum tubes of the 1920s and 1930s and a design philosophy based on simplicity, technical expertise, and careful listening. It is a project for those who appreciate authenticity, value tradition, and wish to rediscover the sonic character of the great classic single-ended amplifiers. For further information about the project and the available components, feel free to contact me directly.