What is the 6C45Pi vacuum tube?

The 6C45Pi is a triode vacuum tube designed for phono / preamp applications. Phenomenal Gm. Surgical..

What is a 6C45Pi substitute or equivalent?

Direct equivalents to the 6C45Pi include 6S45P-E. These share the same pinout and operating envelope, so they can usually be swapped without circuit changes — though batch-to-batch variations between manufacturers (NOS vs current production) may shift the sonic character noticeably.

What are the key specifications of the 6C45Pi?

Amplification factor μ ≈ 52, transconductance gm ≈ 45 mA/V, plate resistance rp ≈ 1.2 kΩ, max plate voltage 150 V, max plate dissipation 7.8 W, heater 6.3 V / 0.44 A.

Is the 6C45Pi still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 6C45Pi as Moderate availability. NOS (new-old-stock) examples from RCA, Mullard, Tung-Sol, GE, Sylvania and Telefunken trade among collectors; modern production where it exists comes mostly from JJ Electronic, Electro-Harmonix, Tung-Sol (New Sensor), Genalex, and a handful of small-batch makers.

What does the 6C45Pi sound like?

Phenomenal Gm. Surgical.. Sonic character also depends heavily on the circuit operating point, the surrounding tubes in the stage, and the output transformer when present — use the interactive loadline calculator on this page to explore the trade-offs.

6C45Pi Triode Vacuum Tube

Also known as 6S45P-E

Medium-gain triode for driver and line stage applications

TriodeHeater 6.3 V · 0.44 A9-pin NovalSovtek 1970

Plate dissipation: 7.8W
Max plate voltage: 150V
Max cathode current: 52mA
Transconductance: 45mA/V

6C45Pi

Characteristics

Datasheet values, once each. Every value cites its sheet.

HeaterIndirectly heated

Specifications of 6C45Pi — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.44 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 6C45Pi — Limiting values
Plate voltageVa max	150 V
Plate dissipationPa max	7.8 W
Cathode currentIk max	52 mA

Mechanical

Specifications of 6C45Pi — Mechanical
Base	9-pin Noval
Rarity	Moderate
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 6C45Pi — Small signal
Transconductance	45 mA/V
Plate resistance	1.2 kΩ
Amplification factor	52

Capacitances

Specifications of 6C45Pi — Capacitances
Grid–cathode	11 pF
Grid–plate	4 pF
Plate–cathode	1.9 pF

Charactereditorial reading, not a measurement

Specifications of 6C45Pi — Character
Gain	52%
Power	20%
Drive	99%
Linearity	74%

datasheet cited · model or editorial reading · catalogue value, no citation attached yet · nothing invented

Using this tube

Interactive loadline calculator not available for this tube yet — it needs calibrated Koren or Ayumi parameters.

Applications

Push-pull output
Voltage amplifier
Headphone output
High-gain preamp
Phono stage

Generic triode phono / preamp stage

Hi-Fi stereoHeadphone ampStudio/recording

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : Soviet-Tubes 6С45П-Е datasheet

Manufacturer datasheets

1 manufacturer datasheets cross-checked for 6C45Pi1 verified

6C45Pi DatasheetFrank's Electron Tube Pages · PDF

SPICE models

Revision and verification status

Source: Soviet-Tubes 6С45П-Е datasheet
Reviewed: 2026-05-29
Status: DataModelCalc
Model: under review

Context

The 6C45Pi is a Russian single triode with extraordinarily high transconductance (~45 mA/V) and very low plate resistance, originally designed for wideband video amplifier and pulse circuit applications. It is one of the most linear small-signal triodes available, with distortion figures an order of magnitude lower than conventional audio tubes at typical operating points. The tube's extreme transconductance makes it challenging to stabilize; careless layout will result in parasitic oscillation, and it demands rigorous power supply decoupling and short signal paths. When properly implemented, it delivers a level of transparency and speed that approaches the best solid-state while retaining dimensional qualities unique to vacuum tubes.

History

Introduced: 1970
Manufacturer: Sovtek
Era: Late Production

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