What is the ECC85 vacuum tube?

The ECC85 is a triode vacuum tube designed for rf / preamp applications. VHF dual triode..

What is a ECC85 substitute or equivalent?

Direct equivalents to the ECC85 include 6AQ8. 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 ECC85?

Amplification factor μ ≈ 57, transconductance gm ≈ 6 mA/V, plate resistance rp ≈ 9.7 kΩ, max plate voltage 550 V, max plate dissipation 2.5 W, heater 6.3 V / 0.435 A.

Is the ECC85 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the ECC85 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 ECC85 sound like?

VHF dual triode.. 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

←ECC85

← ECC83 ECC88 →Compare → 6AQ8

ECC85 Triode Vacuum Tube

Dual triode6.3V / 0.435A9-pin NovalSPICE

SourcePhilips ECC85 datasheetReviewed2026-05-29StatusDataModelCalcModelNorman KorenPDF

Medium-gain triode for driver and line stage applications

Datasheet ↗SPICE

ECC85 — Philips — triode vacuum tube — (1955)

9.7kΩ

6.0mA/V

3.0pF

1.5pF

0.18pF

GAIN57%

POWER6%

DRIVE90%

LINEARITY72%

SPECIFICATIONS

Heater6.3 V · 0.435 A

Max Plate Voltage550 V

Pa max2.5 W

Gain Factor57

gm6 mA/V

rp9.7 kΩ

Inter-electrode capacitances

Cgk3 pF

Cgp1.5 pF

Cpk0.18 pF

Pinout9-pin Noval

Era1955

RarityCommon

HEATER6.3V / 0.435A

MAX PLATE550V / 2.5W

BASEnoval

SECTIONS2 (dual)

Source datasheets

7 manufacturer datasheets cross-checked for ECC85

7 verified

TYPICAL OPERATING POINT

Va150V

Ia4.5mA

Vg-2.13V

Pd0.68W

RL12kΩ

Av30.8dB

EXECUTIVE SUMMARY

The ECC85 is a dual indirectly-heated triode from Philips, introduced around 1955. It provides a gain factor (μ) of 57 with 9700Ω plate resistance. Commonly used in rf / preamp applications. VHF dual triode.

APPLICATIONS

Voltage amplifierHigh-gain preampPhase splitter

Generic triode rf / preamp stage

• Hi-Fi stereo• Headphone amp• Studio/recording

VS 6AQ8

μ 0%Rp +0%Pd 0%Full comparison →

HISTORY

Introduced1955ManufacturerPhilips

Golden Age