The Russian 6N13S (6Н13С) is a low-resistance dual power triode with two separate indirectly heated cathodes, housed in a glass envelope with an octal base. Manufactured by the Svetlana factory in St. Petersburg, it is the electrical equivalent of the 6AS7G and ECC230. The tube was originally designed as a control element in electronic voltage stabilizers, but its low internal resistance and high current capability have made it a favorite in OTL (output transformerless) headphone amplifiers and push-pull audio output stages. It is a New Old Stock (NOS) item, never used.

Key Features & Specifications

• Name: 6N13S / 6H13C / 6Н13С
• Type: dual power triode (low internal resistance)
• Application: voltage regulation, low-frequency power amplification
• Cathode type: oxide, indirect heating (separate cathodes)
• Envelope: glass
• Base: octal, 8-pin
• Filament voltage: 6.3 V ± 0.6 V
• Filament current: 2.5 A ± 0.25 A
• Anode voltage (nominal): 90 V
• Anode current (each triode, nominal): 80 mA ± 32 mA
• Grid voltage (nominal): −30 V
• Transconductance (each triode): 5.5 mA/V ± 1.6 mA/V
• Internal resistance (each triode): 460 Ω
• Input capacitance: 7 pF
• Output capacitance: 4.2 pF
• Grid reverse current: ≤ 2 µA
• Service life: ≥ 2,000 hours
• Dimensions: diameter ≤ 52 mm, seated height ≤ 126 mm

Maximum Ratings

• Max anode voltage: 250 V
• Max cathode current (each triode): 130 mA
• Max anode dissipation (each triode): 13 W
• Max grid circuit resistance (each triode): 1 MΩ
• Max cathode-heater voltage: 300 V

Applications & Compatibility

• Primary use: regulating valve in electronic voltage stabilizers; low-frequency power amplifier in push-pull output stages.
• Audio use: widely used in OTL headphone amplifiers (e.g., Darkvoice 336SE, Feliks Audio Elise & Euforia, Atma-Sphere OTL amplifiers) and as a pass element in tube power supplies.
• Equivalents: 6AS7G, ECC230, 6N5S; also close to 6080, 6080WA, 6AS7GA, 5998, 7236, CV2984, CV5008, CV8216, CV8232.
• Note: the 6N5S is a military-grade variant of the 6N13S.

Condition

• Status: NOS (New Old Stock). Never used.
• Origin: Made in the USSR by the Svetlana factory (St. Petersburg), typically 1970s–1980s production.

Why Choose This Tube?

The 6N13S offers a rare combination of low internal resistance (460 Ω per triode), high current capability (up to 130 mA per section), and robust construction. In OTL headphone amplifiers, it delivers the current swing needed to drive low-impedance headphones without an output transformer, avoiding transformer coloration and bandwidth limitations. In voltage stabilizer circuits, its two independent triodes allow precise regulation with excellent transient response. As a NOS Svetlana product, it is a direct replacement for the 6AS7G and ECC230, making it a practical choice for restoring vintage equipment or building new OTL designs. Its availability and moderate cost have made it a staple among DIY audio enthusiasts and restorers alike.