What is the KT170 vacuum tube?

The KT170 is a tetrode vacuum tube designed for power (pp) applications. Largest KT. Massive headroom..

What is a KT170 substitute or equivalent?

Direct equivalents to the KT170 include KT150 (larger). 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 KT170?

Transconductance gm ≈ 14 mA/V, max plate voltage 900 V, max plate dissipation 85 W, heater 6.3 V / 1.97 A.

Is the KT170 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the KT170 as Moderate 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 KT170 sound like?

Largest KT. Massive headroom.. 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

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KT170 Tetrode Vacuum Tube

Tetrode6.3V / 1.97AOctal

SourceTung-Sol KT170 spec PDFReviewed2026-05-09StatusDataModelCalcModelunder reviewPDF

Beam power tetrode rated at 85W for high-power output stages

Datasheet ↗

KT170 — Tung-Sol — tetrode vacuum tube — (2020)

14.0mA/V

16.5pF

0.9pF

11.50pF

GAIN0%

POWER100%

DRIVE50%

LINEARITY75%

SPECIFICATIONS

Heater6.3 V · 1.97 A

Max Plate Voltage900 V

Pa max85 W

Gain Factor—

gm14 mA/V

rp—

Inter-electrode capacitances

Cgk16.5 pF

Cgp0.9 pF

Cpk11.5 pF

PinoutOctal

Era2020

RarityModerate

HEATER6.3V / 1.97A

MAX PLATE900V / 85W

BASEoctal

EXECUTIVE SUMMARY

The KT170 is a indirectly-heated beam tetrode from Tung-Sol, introduced around 2020. Commonly used in power (pp) applications. Largest KT. Massive headroom.

APPLICATIONS

High-power output

Generic tetrode power (pp) stage

• PA/public address

HISTORY

Introduced2020ManufacturerTung-Sol

Modern

KT170 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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