What is the 6GM8 vacuum tube?

The 6GM8 is a triode vacuum tube designed for preamp applications. Low voltage dual triode..

What is a 6GM8 substitute or equivalent?

Direct equivalents to the 6GM8 include ECC86. 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 6GM8?

Amplification factor μ ≈ 14, transconductance gm ≈ 2.6 mA/V, plate resistance rp ≈ 5.0 kΩ, max plate voltage 30 V, max plate dissipation 0.6 W, heater 6.3 V / 0.33 A.

Is the 6GM8 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 6GM8 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 6GM8 sound like?

Low voltage dual triode.. 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.

6GM8 Triode Vacuum Tube

Also known as ECC86

Low-mu triode with excellent linearity for driver and line stages

Dual triodeHeater 6.3 V · 0.33 A9-pin Noval2 sectionsPhilips 1960

Plate dissipation: 0.6W
Max plate voltage: 30V
Amplification factor: 14
Transconductance: 2.6mA/V
Plate resistance: 5kΩ

6GM8

Characteristics

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

HeaterIndirectly heated

Specifications of 6GM8 — Heater
Heater voltageVh	6.3 V
Heater currentIh	0.33 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 6GM8 — Limiting values
Plate voltageVa max	30 V
Plate dissipationPa max	0.6 W

Mechanical

Specifications of 6GM8 — Mechanical
Base	9-pin Noval
Rarity	Moderate
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 6GM8 — Small signal
Transconductance	2.6 mA/V
Plate resistance	5 kΩ
Amplification factor	14

Capacitances

Specifications of 6GM8 — Capacitances
Grid–cathode	3 pF
Grid–plate	1.3 pF
Plate–cathode	1.8 pF

Charactereditorial reading, not a measurement

Specifications of 6GM8 — Character
Gain	14%
Power	2%
Drive	95%
Linearity	93%

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

Voltage amplifier
Line stage
Phase splitter

Generic triode preamp stage

Hi-Fi stereo

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : Philips ECC86/6GM8 low-V datasheet

Manufacturer datasheets

1 manufacturer datasheets cross-checked for 6GM81 verified

6GM8 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: Philips ECC86/6GM8 low-V datasheet
Reviewed: 2026-05-29
Status: DataModelCalc
Model: under review

Context

The 6GM8 is a dual indirectly-heated triode from Philips, introduced around 1960. It provides a gain factor (μ) of 14 with 5000Ω plate resistance. Commonly used in preamp applications. Low voltage dual triode.

History

Introduced: 1960
Manufacturer: Philips
Era: Late Production

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