Dual low-noise triode.
The 6H1N (Cyrillic 6Н1П, often transliterated as 6N1P) is a rugged, Soviet-era miniature 9-pin (Noval) medium-mu dual triode designed primarily for low-frequency voltage amplification, line stages, and cathode drivers in high-fidelity audio equipment. Operating with a unipotential oxide-coated cathode, its filament requires a 6.3 V AC/DC supply drawing a hefty 600 mA of heater current—nearly double that of a standard 12AU7 or 6DJ8, providing robust thermal stability and high transient current capability. At a typical operating point of 250 V on the plate and a -2 V grid bias (or via a 600-ohm cathode resistor), each triode section exhibits a nominal amplification factor (\(\mu \)) of 33 to 35, a transconductance (\(g_{m}\)) of approximately 4.4 to 4.5 mA/V (4,400 to 4,500 \(\mu\mho\)), and an internal plate resistance (\(r_{p}\)) of around 4,400 ohms. Architecturally, it features an internal electrostatic shield tied to pin 9 to isolate the two triode sections for ultra-low crosstalk, alongside an increased plate dissipation rating of 2.2 Watts per section. While often used as a rugged substitute for the 6DJ8, ECC88, or 6922 in line-level circuits, its distinct electrical envelope offers significantly lower distortion profile and higher maximum anode voltage ratings when appropriately biased.
