What is the ECL84 vacuum tube?

The ECL84 is a pentode vacuum tube designed for power applications.

What is a ECL84 substitute or equivalent?

Direct equivalents to the ECL84 include 6DX8. 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.

Is the ECL84 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the ECL84 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 ECL84 sound like?

Sonic character depends 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

ECL84 Pentode Vacuum Tube

Triode + Pentode6.3 V · 0.72 A9-pin Noval2 sectionsAlso known as6DX8

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : PCL84/ECL84 datasheet (DIYaudio thread) · PCL84/ECL84 datasheet

ECL84

In brief

TriodeTriode

μ: 65
gm: 4 mA/V
rp: 16.25 kΩ
Pa: 1 W

PentodePentode

μ: 36
gm: 10.4 mA/V
rp: 130 kΩ
Pa: 4 W

The ECL84-T is a indirectly-heated triode from Philips, introduced around 1960. It provides a gain factor (μ) of 65 with 16.3kΩ plate resistance. Commonly used in preamp applications. Triode section. The ECL84-P is a indirectly-heated pentode from Philips, introduced around 1960. It provides a gain factor (μ) of 36 with 130.0kΩ plate resistance. Commonly used in power applications. Pentode section.

Limits

Specifications of ECL84
Specification	Value	Source
Heater
Heater voltage	6.3 V	Datasheet
Heater current	0.72 A	Datasheet

Specifications of ECL84-T — Triode
Specification	Value	Source
LimitsDatasheet maximum ratings — not to be exceeded
Max Plate V	250 V	Datasheet
Pa max	1 W	Datasheet

Typical operation

Canonical operating pointModel

B+: 225 V
Load: 33 kΩ
Va: 135 V
Ia: 0.8 mA
Vg: -1.5 V
Pd: 0.11 W
Gain: 32.4 dB

At Q: Norman Koren
μ: 72.5
gm: 1.87 mA/V
rp: 38.7 kΩ

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Using this tube

Open the loadline calculator

APPLICATIONS

Phase splitter

Generic pentode power stage

Replace or compare

Sources

Manufacturer datasheets

Triode

3 manufacturer datasheets cross-checked for ECL84 — Triode3 verified

Pentode

3 manufacturer datasheets cross-checked for ECL84 — Pentode3 verified

ECL84 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: PCL84/ECL84 datasheet (DIYaudio thread) · PCL84/ECL84 datasheet
Reviewed: 2026-05-29
Status: DataModelCalc
Model: SPICE model

Context

HISTORY

Introduced: 1960
Manufacturer: Philips
Era: Late Production

METRIX TESTER