There is a moment in the life of stars when the glow of youth gives way to a subtler, more intense, and mysterious light. It is the moment of the white dwarf, an immortal remnant that keeps shining through the ages, a silent guardian of a stellar memory that does not fade. From this image comes Nyx Aeterna, my new single-ended tube amplifier, inspired by the Greek goddess of the night — Nyx, dark and majestic — and by the concept of eternity — Aeterna, like the light that still pulses from a fragment of a now-silent universe.
Nyx Aeterna is a tribute to pure sound, carved in the penumbra, wrapped in natural harmonics and timeless. A no-compromise project: 2A3 tubes in single-ended configuration for just 3.5 watts RMS of power, yet capable of sculpting every detail with grace and authority. The 6SL7 driver, with its warm, refined character, leads the whole apparatus like an invisible orchestra, while the vacuum rectifier — 5U4G or 5X4G — keeps the amplifier’s soul alive with a voltage that breathes like something ancient.
The sound? Silky, enveloping, twilight. Every note emerges naturally, as if floating in a timeless space, revealing nuances that conventional amplifiers only hint at. This isn’t about brute force, but intimacy — musical truth. It’s an experience to be heard in the dark, as one contemplates the starry sky: in silence, with respect.
Origins of Nyx Aeterna – From forgotten scrap to a new creature
Nyx Aeterna was born from what many would simply call “an old Chinese amp” — one of the many clones of the Single Ended Sun Audio SV2A3, like the Bowie SG-280SE or the Bowey 2A3C and similar others, sold in the past or even today on various bazaars for little money, now forgotten in dusty attics or damp basements. Abandoned objects, sometimes damaged, with slapdash circuits and cheap components. But with a chassis that, if desired, can become the foundation for something completely different.
In my view, there’s only one sensible way to “modify” these amplifiers: start from scratch. We’re not talking about swapping a couple of resistors or a pair of capacitors and hoping for audiophile miracles. When I take them on, the changes are so radical that, in the end, only the shell remains. It’s a total reconstruction, not a restyling.
So does it make sense to buy such an amp on purpose and then rebuild it from the ground up? Probably not, if you have to pay for it. But if you already own one, or you pick it up for little, reusing at least the chassis and some mechanical parts can be a smart choice: the enclosure is ready, the holes are drilled, the tube sockets are mounted — and that’s a nice saving in time and money.
Nyx Aeterna was born exactly this way: not from an upgrade, but from an act of technical rebirth. It is not a Sun Audio clone, nor a variation on its theme. The circuit is completely new, designed from scratch around SB-LAB output and power transformers, chosen to enhance the 2A3’s tone and to ensure stability, silence, and dynamic coherence. The wiring has been entirely redone by hand, following high-level construction criteria, with no compromises.
What began as a budget amplifier has been emptied, cleaned, and reassembled with a brand-new heart and soul. And today, Nyx Aeterna tells another story. Its own.
Disassemble, sandblast, be reborn
The first step was the most obvious: completely disassemble the starting amplifier. Screws, wires, sockets, components… everything removed until only the bare chassis remained, still bearing the marks of time. The original glossy paint of these devices, as often happens, was fragile and marred: deep scratches, indelible stains, dull halos, and in some spots even traces of rust beginning to creep out from under the finish. The classic fate of Chinese clones forgotten in some damp stairwell.
Before proceeding, I drilled a couple of additional holes to adapt the layout to my new circuit. Then, the chassis was sandblasted, to achieve a complete stripping and, above all, a slightly rough surface — ideal for giving grip to the new powder coating. The final result is a black, orange-peel effect finish, much more robust, scratch-resistant, and with a look that is both technical and elegant.
In the end, very little of the original amplifier remains: the chassis, with its characteristic transformer cans, the sockets, the RCA jacks, the banana posts for the speakers, a few power resistors, the IEC inlet, the LED indicator, the front knobs, and some small internal hardware. Everything else was removed, replaced, rethought from scratch.
In the following photos you can see the two SE2K5-2A3 output transformers, designed expressly for use with 2A3 tubes in single-ended configuration, and the 23S48 power transformer, sized to ensure stability and a silent background. For this build they were made with mounting frames instead of the usual covers — a functional choice necessary to house them inside the original sheet-metal boxes of the Chinese chassis without giving up robustness and shielding.
Alongside them, the 18S5200 choke, an integral part of the inductive power supply group that ensures clean, deep filtering. The entire transformer set — SE2K5-2A3, 23S48, and 18S5200 together with the complete schematic — is available as a premium schematic, for those who want to replicate a similar project starting from components selected and designed specifically for this topology.
In the next step, I created and installed a bakelite board on which all the sockets were mounted, ready to receive the point-to-point wiring. A neat, robust, and easily serviceable solution. The board was assembled together with the transformers and the chassis, marking the point of no return: from that moment on, Nyx Aeterna was taking concrete shape.
In the following photo you can see the complete wiring of the circuit, done strictly by hand, with careful attention to grounding paths, separation between signal and power, and an orderly, functional aesthetic. Every component was chosen for reliability, electrical characteristics, and sonic coherence, avoiding excessive fads as well as bargain-bin solutions.
Finally, the personal touch: the decorative front effigy. I laser-engraved a small piece of Italian walnut, cut from an ~80-year-old board, with an evocative decoration that echoes rococo style and the nocturnal mystery of the device’s name. At the center, the name Nyx Aeterna, accompanied by the SB-LAB logo. A signature, a statement of identity. An amplifier is not judged only by how it sounds, but also by how it tells its own story, even before the music begins.
Instrument measurements – Concrete data to support the listening
Nyx Aeterna is not just aesthetic and timbral suggestion: behind the craftsmanship and elegance of the sound lies a technically solid design, confirmed by instrument measurements carried out with laboratory equipment.
- Undistorted RMS power: 3 watts
- Clipping power: 3.7 watts
- Bandwidth at -1 dB: from 18 Hz to 38 kHz, a wide, well-extended response that delivers body and detail even to the most complex recordings
- Damping factor: 4.4 — a balanced value that ensures good control of reactive loads without sacrificing musicality
- THD @ 1 watt: 1% — a natural, pleasant harmonic distortion, perfectly in line with the single-ended triode philosophy
To complete the picture, the square waveforms at 100 Hz, 1 kHz, and 10 kHz show a well-controlled response, free from excessive resonances or phase shifts. The behavior of the output transformer is stable, with no marked overshoot, and with crisp, symmetrical transients — evidence of the high design and build quality of the magnetic section.
Nyx Aeterna – The end of one journey, the beginning of another
In the final images you can admire Nyx Aeterna in its finished form: elegant, solid, refined in the details. The device comes with CE marking, an instruction manual, a declaration of conformity, and a 2-year warranty, like any object designed and built with technical care and artisanal responsibility.
>>> But Nyx Aeterna is not just a one-off. It is also a possibility. <<<
If you have one of these little Chinese 2A3 amplifiers at home — perhaps forgotten for years, with marred paint and a hum you never got around to fixing — know that it can be reborn. Even if it’s off, even if you no longer use it. Entrust it to me, and it will become something completely different: not an upgrade, not a tweak, but a new creature. A Nyx Aeterna!
And if you’re starting from scratch or you’re a DIY builder, note that the complete set of transformers designed specifically for this circuit (power, output, choke) is available as a premium schematic along with the support needed to build your own version of the project.
