What is the 26 vacuum tube?

The 26 (26 / UX-226) is a triode vacuum tube designed for preamp applications. Creamy tone. Early DHT magic..

What is a 26 substitute or equivalent?

Direct equivalents to the 26 include UX-226, CX-326. 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 26?

Amplification factor μ ≈ 8, transconductance gm ≈ 1.1 mA/V, plate resistance rp ≈ 7.6 kΩ, max plate voltage 180 V, max plate dissipation 1.5 W, heater 1.5 V / 1.05 A.

Is the 26 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 26 as Collector 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 26 sound like?

Creamy tone. Early DHT magic.. 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.

26 UX-226 Triode Vacuum Tube

Also known as UX-226 · CX-326

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

TriodeHeater 1.5 V · 1.05 AUX-4RCA·GE 1926

Plate dissipation: 1.5W
Max plate voltage: 180V
Amplification factor: 8
Transconductance: 1.1mA/V
Plate resistance: 7.6kΩ

Characteristics

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

HeaterDirectly heated

Specifications of 26 — Heater
Heater voltageVh	1.5 V
Heater currentIh	1.05 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of 26 — Limiting values
Plate voltageVa max	180 V
Plate dissipationPa max	1.5 W

Mechanical

Specifications of 26 — Mechanical
Base	UX-4
Rarity	Collector
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of 26 — Small signal
Transconductance	1.1 mA/V
Plate resistance	7.6 kΩ
Amplification factor	8

Capacitances

Specifications of 26 — Capacitances
Grid–cathode	2.8 pF
Grid–plate	8.1 pF
Plate–cathode	2.5 pF

Charactereditorial reading, not a measurement

Specifications of 26 — Character
Gain	8%
Power	4%
Drive	92%
Linearity	95%

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

Generic triode preamp stage

Hi-Fi stereoHeadphone amp

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026

Manufacturer datasheets

5 manufacturer datasheets cross-checked for 26 / UX-2265 verified

26 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: RCA·GE
Reviewed: 2026-05-29
Status: DataModelCalc
Model: under review

Context

The 26 is a directly-heated triode from RCA·GE, introduced around 1926. It provides a gain factor (μ) of 8 with 7600Ω plate resistance. Commonly used in preamp applications. Creamy tone. Early DHT magic.

History

Introduced: 1926
Manufacturer: RCA·GE
Era: Pre-War

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