What is the RE604 vacuum tube?

The RE604 is a triode vacuum tube designed for power (se) applications. Legendary German DHT. Cinema heritage..

What is a RE604 substitute or equivalent?

Direct equivalents to the RE604 include AD1. 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 RE604?

Amplification factor μ ≈ 4, transconductance gm ≈ 3.5 mA/V, plate resistance rp ≈ 1.5 kΩ, max plate voltage 200 V, max plate dissipation 12 W, heater 4 V / 0.65 A.

Is the RE604 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the RE604 as Legendary 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 RE604 sound like?

Legendary German DHT. Cinema heritage.. 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.

RE604 Triode Vacuum Tube

Also known as AD1

High-power directly-heated triode for single-ended amplification

TriodeHeater 4 V · 0.65 A4-pin EuropeanTelefunken 1929

Plate dissipation: 12W
Max plate voltage: 200V
Transconductance: 3.5mA/V

RE604

Characteristics

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

HeaterDirectly heated

Specifications of RE604 — Heater
Heater voltageVh	4 V
Heater currentIh	0.65 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of RE604 — Limiting values
Plate voltageVa max	200 V
Plate dissipationPa max	12 W

Mechanical

Specifications of RE604 — Mechanical
Base	4-pin European
Rarity	Legendary
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of RE604 — Small signal
Transconductance	3.5 mA/V
Plate resistance	1.5 kΩ
Amplification factor	4

Capacitances

Specifications of RE604 — Capacitances
Grid–cathode	4 pF
Grid–plate	5.5 pF
Plate–cathode	3 pF

Charactereditorial reading, not a measurement

Specifications of RE604 — Character
Gain	4%
Power	30%
Drive	99%
Linearity	95%

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

Using this tube

Interactive loadline calculator not available for this tube yet — it needs calibrated Koren or Ayumi parameters.

Applications

SET output
Push-pull output
Headphone output

Generic triode power (se) stage

Hi-Fi stereoHeadphone amp

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : Telefunken RE604 (radiomuseum.org)

Manufacturer datasheets

2 manufacturer datasheets cross-checked for RE6042 verified

RE604 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: Telefunken RE604 (radiomuseum.org)
Reviewed: 2026-05-29
Status: DataModelCalc
Model: under review

Context

The RE604 is a directly-heated triode from Telefunken, introduced around 1929. It provides a gain factor (μ) of 4 with 1500Ω plate resistance. Commonly used in power (se) applications. Legendary German DHT. Cinema heritage.

History

Introduced: 1929
Manufacturer: Telefunken
Era: Pre-War

METRIX TESTER