What is the 6U8A-T vacuum tube?

The 6U8A-T (6U8A (Triode)) is a triode vacuum tube designed for preamp applications. Triode section..

What is a 6U8A-T substitute or equivalent?

Direct equivalents to the 6U8A-T include ECF82. 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 6U8A-T?

Amplification factor μ ≈ 40, transconductance gm ≈ 7.5 mA/V, plate resistance rp ≈ 5.4 kΩ, max plate voltage 330 V, max plate dissipation 2.5 W, heater 6.3 V / 0.45 A.

Is the 6U8A-T still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 6U8A-T 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 6U8A-T sound like?

Triode section.. 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.

By Jean-Michel Falligan Devergne · Reviewed May 29, 2026

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6U8A-T 6U8A (Triode) Triode Vacuum Tube

Triode6.3V / 0.45A9-pin Noval

Sourceaudit-us_b (CLEAN — matches canonical datasheet)Reviewed2026-05-29StatusDataModelCalcModelunder reviewPDF

Medium-gain triode for driver and line stage applications

Datasheet ↗

6U8A (Triode) — RCA — triode vacuum tube — (1955)

5.4kΩ

7.5mA/V

2.8pF

1.8pF

1.50pF

GAIN40%

POWER6%

DRIVE95%

LINEARITY80%

SPECIFICATIONS

Heater6.3 V · 0.45 A

Max Plate Voltage330 V

Pa max2.5 W

Gain Factor40

gm7.5 mA/V

rp5.4 kΩ

Inter-electrode capacitances

Cgk2.8 pF

Cgp1.8 pF

Cpk1.5 pF

Pinout9-pin Noval

Era1955

RarityCommon

HEATER6.3V / 0.45A

MAX PLATE330V / 2.5W

BASEnoval

Source datasheets

3 manufacturer datasheets cross-checked for 6U8A (Triode)

3 verified

EXECUTIVE SUMMARY

The 6U8A-T is a indirectly-heated triode from RCA, introduced around 1955. It provides a gain factor (μ) of 40 with 5400Ω plate resistance. Commonly used in preamp applications. Triode section.

APPLICATIONS

Voltage amplifier

Generic triode preamp stage

• Hi-Fi stereo• Headphone amp

HISTORY

Introduced1955ManufacturerRCA

Golden Age

6U8A-T Datasheet

Local mirror · PDF

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METRIX TESTER

Test this tube on a Metrix

SPICE model not yet available. Loadline calculator requires calibrated Koren parameters.

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