Balanced Audio Technology VK-56SE POWER AMPLIFIER
I had never been alone with a Russian-manufactured 6C33C tube. At least not at night, in the dark. The first night Balanced Audio Technology’s VK-56SE tubed amplifier was in my system, I sat on the floor studying the unusual shape and dark orange glow of its four 6C33C-B output tubes. I noticed their brightly lit, cathedral-like innards. My Russian neighbor told me they were used as regulator tubes in MIG jets during the Cold War. I could believe it—their exposed cathodes were the exact color of the Soviet flag. From more than a foot away, I could feel the heat from their high-amperage filaments.
The next morning, I pulled a cold 6C33C-B from its socket and examined it in sunlight. Its glass envelope seemed thick. It felt like a tube that wouldn’t break if I dropped it. I was fascinated by its vast crown of chrome-colored getter-flash, punctuated by three support-rod nipples. I was impressed by the thickness of the bronze side rods and the laminated graphite-titanium plate structure.1
Sitting at my desk in the winter sun, I remembered: Once upon a time I was skeptical of using industrial-strength series-regulator tubes as audio-frequency amplifiers. Why? Because in my DIY experiments, 6AS7/6080 dual-triode tubes had sounded clean, but decidedly not subtle or rich of tone.
I imagine Victor Khomenko dreaming about these hot-filament tubes at an early age.
Historically, smart engineers designed vacuum tubes to operate in specific ways under specific conditions. Rarely did tubes excel at they want more power than the few watts those Hall-of-Fame triodes can deliver. But in the case of the 6C33C-Bs in the VK-56SE, I suspect BAT had another, more relevant reason.
