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.

ECL84 Pentode Vacuum Tube

Also known as 6DX8

Triode + PentodeHeater 6.3 V · 0.72 A9-pin Noval2 sectionsPhilips 1960

Triode · Plate dissipation: 1W
Triode · Amplification factor: 65
Pentode · Plate dissipation: 4W
Pentode · Amplification factor: 36

ECL84

Characteristics

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

HeaterIndirectly heated

Specifications of ECL84 — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.72 A

Mechanical

Specifications of ECL84 — Mechanical
Base	9-pin Noval
Rarity	Common
Pinout

TriodeTriode

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of ECL84-T — Triode — Limiting values
Plate voltageVa max	250 V
Screen voltageVg2 max	250 V
Plate dissipationPa max	1 W
Cathode currentIk max	40 mA
Grid resistorRg1 max	1 MΩ
Peak plate voltageVao	550 V

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of ECL84-T — Triode — Small signal
Transconductance	4 mA/V
Plate resistance	16.3 kΩ
Amplification factor	65

Capacitances

Specifications of ECL84-T — Triode — Capacitances
Grid–cathode	3.9 pF
Grid–plate	2.7 pF
Plate–cathode	2.3 pF

Charactereditorial reading, not a measurement

Specifications of ECL84-T — Triode — Character
Gain	65%
Power	3%
Drive	84%
Linearity	68%

PentodePentode

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of ECL84-P — Pentode — Limiting values
Plate voltageVa max	250 V
Screen voltageVg2 max	250 V
Plate dissipationPa max	4 W
Cathode currentIk max	40 mA
Peak plate voltageVao	550 V

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of ECL84-P — Pentode — Small signal
Transconductance	10.4 mA/V
Plate resistance	130 kΩ
Amplification factor	36

Capacitances

Specifications of ECL84-P — Pentode — Capacitances
Input	8.7 pF
Grid–plate	0.1 pF
Output	4.2 pF

Charactereditorial reading, not a measurement

Specifications of ECL84-P — Pentode — Character
Gain	36%
Power	10%
Drive	0%
Linearity	82%

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

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

Design a stage →

Using this tube

Applications

Phase splitter

Generic pentode power stage

Replace or compare

Sources

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

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

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.

History

Introduced: 1960
Manufacturer: Philips
Era: Late Production

METRIX TESTER

Characteristics

HeaterIndirectly heated

Mechanical

TriodeTriode

Limiting valuesDatasheet maximum ratings — not to be exceeded

Small signalDatasheet parameters at the reference operating point — not limits

Capacitances

Charactereditorial reading, not a measurement?

PentodePentode

Limiting valuesDatasheet maximum ratings — not to be exceeded

Small signalDatasheet parameters at the reference operating point — not limits

Capacitances

Charactereditorial reading, not a measurement?

Typical operation

Using this tube

Applications

Replace or compare

Versus 12SJ7

Similar tubes

Sources

Manufacturer datasheets

SPICE models

Context

History

Test this tube on a Metrix

Charactereditorial reading, not a measurement

Charactereditorial reading, not a measurement