What is the 3A5 vacuum tube?

The 3A5 is a triode vacuum tube designed for portable power applications. Battery power tube..

What is a 3A5 substitute or equivalent?

Direct equivalents to the 3A5 include DL94 equiv. 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 3A5?

Amplification factor μ ≈ 15, transconductance gm ≈ 1.8 mA/V, plate resistance rp ≈ 8.3 kΩ, max plate voltage 135 V, max plate dissipation 0.5 W, heater 1.4 V / 0.22 A.

Is the 3A5 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 3A5 as Moderate 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 3A5 sound like?

Battery power tube.. 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.

3A5 Triode Vacuum Tube

Also known as DL94 equiv

Medium-gain triode for driver and line stage applications

Dual triodeHeater 1.4 V · 0.22 A7-pin Miniature2 sectionsRCA 1950

Plate dissipation: 0.5W
Max plate voltage: 135V
Amplification factor: 15
Transconductance: 1.8mA/V
Plate resistance: 8.3kΩ

3A5

Characteristics

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

HeaterDirectly heated

Specifications of 3A5 — Heater
Heater voltageVh	1.4 V
Heater currentIh	0.22 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 3A5 — Limiting values
Plate voltageVa max	135 V
Plate dissipationPa max	0.5 W

Mechanical

Specifications of 3A5 — Mechanical
Base	7-pin Miniature
Rarity	Moderate
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 3A5 — Small signal
Transconductance	1.8 mA/V
Plate resistance	8.3 kΩ
Amplification factor	15

Capacitances

Specifications of 3A5 — Capacitances
Grid–cathode	0.9 pF
Grid–plate	3.2 pF
Plate–cathode	1 pF

Charactereditorial reading, not a measurement

Specifications of 3A5 — Character
Gain	15%
Power	1%
Drive	92%
Linearity	93%

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

Typical operation

Canonical operating pointModel

B+: 135 V
Load: 5 kΩ
Va: 81 V
Ia: 3.95 mA
Vg: -3 V
Pd: 0.32 W
Gain: 17.2 dB

At Q: Norman Koren
μ: 17.6
gm: 1.86 mA/V
rp: 9.4 kΩ

Design a stage →

Using this tube

Applications

Line stage
Phase splitter

Generic triode portable power stage

Hi-Fi stereo

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : r-type.org 3A5 / amplifiedparts 3A5/DCC90Active model : Norman Koren

Manufacturer datasheets

2 manufacturer datasheets cross-checked for 3A52 verified

3A5 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: r-type.org 3A5 / amplifiedparts 3A5/DCC90
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Norman Koren

Context

The 3A5 is a dual directly-heated triode from RCA, introduced around 1950. It provides a gain factor (μ) of 15 with 8300Ω plate resistance. Commonly used in portable power applications. Battery power tube.

History

Introduced: 1950
Manufacturer: RCA
Era: Golden Age

METRIX TESTER