What is the TT22 vacuum tube?

The TT22 is a tetrode vacuum tube designed for power (pp) applications. 12V heater KT88 variant. RF/Audio crossover..

What is a TT22 substitute or equivalent?

Direct equivalents to the TT22 include KT88 (different pinout, 12V heater). 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 TT22?

Transconductance gm ≈ 11.5 mA/V, max plate voltage 1250 V, max plate dissipation 45 W, heater 12.6 V / 0.8 A.

Is the TT22 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the TT22 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 TT22 sound like?

12V heater KT88 variant. RF/Audio crossover.. 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 9, 2026

←TT22

← TT21 UCL82-P →Compare…

TT22 Tetrode Vacuum Tube

Tetrode12.6V / 0.8AOctal + Top Cap

SourceGEC TT22 datasheet (tubedatabase)Reviewed2026-05-09StatusDataModelCalcModelunder reviewPDF

Beam power tetrode rated at 45W for high-power output stages

Datasheet ↗

TT22 — GEC·MOV — tetrode vacuum tube — (1957)

11.5mA/V

12.0pF

0.5pF

8.00pF

GAIN0%

POWER100%

DRIVE50%

LINEARITY75%

SPECIFICATIONS

Heater12.6 V · 0.8 A

Max Plate Voltage1250 V

Pa max45 W

Gain Factor—

gm11.5 mA/V

rp—

Inter-electrode capacitances

Cgk12 pF

Cgp0.5 pF

Cpk8 pF

PinoutOctal + Top Cap

Era1957

RarityCollector

HEATER12.6V / 0.8A

MAX PLATE1250V / 45W

BASEoctal

EXECUTIVE SUMMARY

The TT22 is a indirectly-heated beam tetrode from GEC·MOV, introduced around 1957. Commonly used in power (pp) applications. 12V heater KT88 variant. RF/Audio crossover.

APPLICATIONS

High-power output

Generic tetrode power (pp) stage

• PA/public address

HISTORY

Introduced1957ManufacturerGEC·MOV

Golden Age

TT22 Datasheet

Frank's Electron Tube Pages · PDF

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METRIX TESTER

Test this tube on a Metrix

SPICE model not yet available. Loadline calculator requires calibrated Koren parameters.

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