What is the 6J5 vacuum tube?

The 6J5 is a triode vacuum tube designed for preamp applications. Half a 6SN7. Same lush musicality..

What is a 6J5 substitute or equivalent?

Direct equivalents to the 6J5 include L63, CV1932. 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 6J5?

Amplification factor μ ≈ 20, transconductance gm ≈ 2.6 mA/V, plate resistance rp ≈ 7.7 kΩ, max plate voltage 300 V, max plate dissipation 2.5 W, heater 6.3 V / 0.3 A.

Is the 6J5 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 6J5 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 6J5 sound like?

Half a 6SN7. Same lush musicality.. 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.

6J5 Triode Vacuum Tube

Also known as L63 · CV1932

Medium-gain triode for driver and line stage applications

TriodeHeater 6.3 V · 0.3 AOctalRCA·Sylvania 1939

Plate dissipation: 2.5W
Max plate voltage: 300V
Amplification factor: 20
Transconductance: 2.6mA/V
Plate resistance: 7.7kΩ

6J5

Characteristics

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

HeaterIndirectly heated

Specifications of 6J5 — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.3 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 6J5 — Limiting values
Plate voltageVa max	300 V
Plate dissipationPa max	2.5 W

Mechanical

Specifications of 6J5 — Mechanical
Base	Octal
Rarity	Moderate
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 6J5 — Small signal
Transconductance	2.6 mA/V
Plate resistance	7.7 kΩ
Amplification factor	20

Capacitances

Specifications of 6J5 — Capacitances
Grid–cathode	3.4 pF
Grid–plate	3.4 pF
Plate–cathode	3.6 pF

Charactereditorial reading, not a measurement

Specifications of 6J5 — Character
Gain	20%
Power	6%
Drive	92%
Linearity	90%

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

Typical operation

Canonical operating pointModel

B+: 350 V
Load: 12 kΩ
Va: 210 V
Ia: 3.99 mA
Vg: -8.8 V
Pd: 0.84 W
Gain: 20.9 dB

At Q: Norman Koren
μ: 19.5
gm: 2.05 mA/V
rp: 9.5 kΩ

Design a stage →

Using this tube

Applications

Voltage amplifier

Generic triode preamp stage

Hi-Fi stereoHeadphone amp

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Active model : Norman Koren

Manufacturer datasheets

6 manufacturer datasheets cross-checked for 6J56 verified

6J5 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: RCA·Sylvania
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Norman Koren

Context

The 6J5 is a single-triode octal tube that is essentially one half of a 6SN7, with a mu of ~20 and plate resistance of ~7.7k ohms. Using two separate 6J5s instead of one 6SN7 eliminates crosstalk between sections and allows independent tube selection for each channel, which purists argue yields a blacker background and better channel separation. The tube was ubiquitous in 1940s radio and early television and is readily available as NOS in large quantities at modest cost. Its single-triode construction makes it a natural choice for minimalist preamp designs where each gain stage gets its own dedicated tube.

History

Introduced: 1939
Manufacturer: RCA·Sylvania
Era: Pre-War

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