What is the ECF80-T vacuum tube?

The ECF80-T (ECF80 (Triode)) is a triode vacuum tube designed for preamp applications. Triode section..

What is a ECF80-T substitute or equivalent?

Direct equivalents to the ECF80-T include 6BL8. 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 ECF80-T?

Amplification factor μ ≈ 20, transconductance gm ≈ 5 mA/V, plate resistance rp ≈ 4.0 kΩ, max plate voltage 250 V, max plate dissipation 1.5 W, heater 6.3 V / 0.43 A.

Is the ECF80-T still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the ECF80-T as Common 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 ECF80-T sound like?

Triode section.. 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.

By Jean-Michel Falligan Devergne · Reviewed May 29, 2026

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ECF80-T ECF80 (Triode) Triode Vacuum Tube

Triode6.3V / 0.43A9-pin NovalSPICE

SourcePhilips ECF80 datasheetReviewed2026-05-29StatusDataModelCalcModelNorman KorenPDF

Medium-gain triode for driver and line stage applications

Datasheet ↗SPICE

ECF80 (Triode) — Philips — triode vacuum tube — (1955)

4.0kΩ

5.0mA/V

2.5pF

1.5pF

1.80pF

GAIN20%

POWER4%

DRIVE96%

LINEARITY90%

SPECIFICATIONS

Heater6.3 V · 0.43 A

Max Plate Voltage250 V

Pa max1.5 W

Gain Factor20

gm5 mA/V

rp4.0 kΩ

Inter-electrode capacitances

Cgk2.5 pF

Cgp1.5 pF

Cpk1.8 pF

Pinout9-pin Noval

Era1955

RarityCommon

HEATER6.3V / 0.43A

MAX PLATE250V / 1.5W

BASEnoval

Source datasheets

6 manufacturer datasheets cross-checked for ECF80 (Triode)

6 verified

TYPICAL OPERATING POINT

Va135V

Ia8.7mA

Vg-5V

Pd1.17W

RL8kΩ

Av23dB

EXECUTIVE SUMMARY

The ECF80-T is a indirectly-heated triode from Philips, introduced around 1955. It provides a gain factor (μ) of 20 with 4000Ω plate resistance. Commonly used in preamp applications. Triode section.

APPLICATIONS

Voltage amplifier

Generic triode preamp stage

• Hi-Fi stereo• Headphone amp

HISTORY

Introduced1955ManufacturerPhilips

Golden Age

ECF80-T Datasheet

Local mirror · PDF

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METRIX TESTER

Test this tube on a Metrix

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