What is the 6BQ7A vacuum tube?

The 6BQ7A is a triode vacuum tube designed for rf / preamp applications. Cascode RF dual triode..

What is a 6BQ7A substitute or equivalent?

Direct equivalents to the 6BQ7A include None. 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 6BQ7A?

Amplification factor μ ≈ 38, transconductance gm ≈ 6.4 mA/V, plate resistance rp ≈ 5.9 kΩ, max plate voltage 250 V, max plate dissipation 2 W, heater 6.3 V / 0.4 A.

Is the 6BQ7A still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 6BQ7A 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 6BQ7A sound like?

Cascode RF 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.

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

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6BQ7A Triode Vacuum Tube

Dual triode6.3V / 0.4A9-pin NovalSPICE

Sourceaudit-us_a (CLEAN — matches canonical datasheet)Reviewed2026-05-29StatusDataModelCalcModelNorman KorenPDF

Medium-gain triode for driver and line stage applications

Datasheet ↗SPICE

6BQ7A — RCA — triode vacuum tube — (1955)

5.9kΩ

6.4mA/V

2.9pF

1.1pF

1.35pF

GAIN38%

POWER5%

DRIVE94%

LINEARITY81%

SPECIFICATIONS

Heater6.3 V · 0.4 A

Max Plate Voltage250 V

Pa max2 W

Gain Factor38

gm6.4 mA/V

rp5.9 kΩ

Inter-electrode capacitances

Cgk2.85 pF

Cgp1.15 pF

Cpk1.35 pF

Pinout9-pin Noval

Era1955

RarityCommon

HEATER6.3V / 0.4A

MAX PLATE250V / 2W

BASEnoval

SECTIONS2 (dual)

Source datasheets

5 manufacturer datasheets cross-checked for 6BQ7A

5 verified

TYPICAL OPERATING POINT

Va120V

Ia1.76mA

Vg-3V

Pd0.21W

RL5kΩ

Av19.6dB

EXECUTIVE SUMMARY

The 6BQ7A is a dual indirectly-heated triode from RCA, introduced around 1955. It provides a gain factor (μ) of 38 with 5900Ω plate resistance. Commonly used in rf / preamp applications. Cascode RF dual triode.

APPLICATIONS

Voltage amplifierPhase splitter

Generic triode rf / preamp stage

• Hi-Fi stereo• Headphone amp

HISTORY

Introduced1955ManufacturerRCA

Golden Age

6BQ7A Datasheet

Local mirror · PDF

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METRIX TESTER

Test this tube on a Metrix

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