What is the ECC99 vacuum tube?

The ECC99 is a triode vacuum tube designed for driver / power applications. Modern powerhouse..

What are the key specifications of the ECC99?

Amplification factor μ ≈ 22, transconductance gm ≈ 9.5 mA/V, plate resistance rp ≈ 2.3 kΩ, max plate voltage 400 V, max plate dissipation 5 W, heater 6.3 V / 0.4 A.

Is the ECC99 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the ECC99 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 ECC99 sound like?

Modern powerhouse.. 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.

ECC99 Triode Vacuum Tube

Medium-gain triode for driver and line stage applications

Dual triodeHeater 6.3 V · 0.4 A9-pin Noval2 sectionsJJ Electronic 2000

Plate dissipation: 5W
Max plate voltage: 400V
Transconductance: 9.5mA/V

ECC99

Characteristics

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

HeaterIndirectly heated

Specifications of ECC99 — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.4 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of ECC99 — Limiting values
Plate voltageVa max	400 V
Plate dissipationPa max	5 W

Mechanical

Specifications of ECC99 — Mechanical
Base	9-pin Noval
Rarity	Common
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of ECC99 — Small signal
Transconductance	9.5 mA/V
Plate resistance	2.3 kΩ
Amplification factor	22

Capacitances

Specifications of ECC99 — Capacitances
Grid–cathode	5 pF
Grid–plate	1.4 pF
Plate–cathode	2.3 pF

Charactereditorial reading, not a measurement

Specifications of ECC99 — Character
Gain	22%
Power	13%
Drive	98%
Linearity	89%

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

Using this tube

Applications

Push-pull output
Phase splitter

Generic triode driver / power stage

Hi-Fi stereoHeadphone amp

Classic circuits

ECC99 Headphone Output
Headphone Amp0.5W
JJ ECC99 as headphone output stage. High-current dual triode designed for low-impedance loads. Drives headphones directly without OPT.
SEVb 200V · Vg -12V · RL 600ΩJJ ECC99 Datasheet

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : JJ Electronic ECC99 OEM datasheetActive model : Norman Koren

Manufacturer datasheets

ECC99 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: JJ Electronic ECC99 OEM datasheet
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Norman Koren

Context

The ECC99 is a modern dual triode designed by JJ Electronic specifically for audio driver applications, with no direct vintage equivalent. It features a mu of ~22 and unusually low plate resistance (~2.4k ohms per section), giving it exceptional current delivery and load-driving capability for a small-signal tube. The ECC99 can swing large voltages while sourcing significant current, making it an ideal driver for power triodes like the 300B or 2A3 in transformer-coupled or interstage-coupled designs. Its modern design and robust construction make it a practical choice for new amplifier designs that need a strong octal-based driver stage.

History

Introduced: 2000
Manufacturer: JJ Electronic
Era: Modern

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