What is the 6AQ5 vacuum tube?

The 6AQ5 (6AQ5 / EL90) is a tetrode vacuum tube designed for power applications. Compact power..

What is a 6AQ5 substitute or equivalent?

Direct equivalents to the 6AQ5 include EL90, 6005. 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 6AQ5?

Amplification factor μ ≈ 10, transconductance gm ≈ 4.1 mA/V, plate resistance rp ≈ 52.0 kΩ, max plate voltage 250 V, max plate dissipation 12 W, heater 6.3 V / 0.45 A.

Is the 6AQ5 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 6AQ5 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 6AQ5 sound like?

Compact power.. 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

←6AQ5

← 6AK6 6AQ8 →Compare → EL90

6AQ5 6AQ5 / EL90 Tetrode Vacuum Tube

Tetrode6.3V / 0.45A7-pin MiniatureSPICE

Sourceaudit-us_a (CLEAN — matches canonical datasheet)Reviewed2026-05-29StatusDataModelCalcModelKoren pentodePDF

Beam power tetrode rated at 12W for high-power output stages

Datasheet ↗SPICE

6AQ5 / EL90 — RCA — tetrode vacuum tube — (1950)

52.0kΩ

4.1mA/V

8.0pF

0.4pF

8.50pF

GAIN10%

POWER30%

DRIVE48%

LINEARITY95%

SPECIFICATIONS

Heater6.3 V · 0.45 A

Max Plate Voltage250 V

Pa max12 W

Gain Factor10

gm4.1 mA/V

rp52.0 kΩ

Inter-electrode capacitances

Cgk8 pF

Cgp0.4 pF

Cpk8.5 pF

Pinout7-pin Miniature

Era1950

RarityCommon

HEATER6.3V / 0.45A

MAX PLATE250V / 12W

BASEminiature-7

Source datasheets

4 manufacturer datasheets cross-checked for 6AQ5 / EL90

4 verified

Triode-connectedTung-Sol1956-1959 (Plate #5435 March 1, 1959 / Plate #4689 June 1, 1956)

Specs when the screen grid (g2) is tied to the anode — the tube acts as a triode.

0.5

According to Tung-Sol (Tung-Sol Electric Inc., Bloomfield NJ) (1956-1959 (Plate #5435 March 1, 1959 / Plate #4689 June 1, 1956)): « TRIODE CONNECTED »

EXECUTIVE SUMMARY

The 6AQ5 is a indirectly-heated beam tetrode from RCA, introduced around 1950. It provides a gain factor (μ) of 10 with 52.0kΩ plate resistance. Commonly used in power applications. Compact power.

VS EL90

Rp +0%Pd 0%Full comparison →

HISTORY

Introduced1950ManufacturerRCA

Golden Age