What is the EL90 vacuum tube?

The EL90 is a tetrode vacuum tube designed for power applications. European 6AQ5..

What is a EL90 substitute or equivalent?

Direct equivalents to the EL90 include 6AQ5. 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 EL90?

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 EL90 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the EL90 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 EL90 sound like?

European 6AQ5.. 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.