What is the CV1040 vacuum tube?

The CV1040 is a triode vacuum tube designed for power (set) applications. British military DHT..

What is a CV1040 substitute or equivalent?

Direct equivalents to the CV1040 include PX25. 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 CV1040?

Amplification factor μ ≈ 10, transconductance gm ≈ 7 mA/V, plate resistance rp ≈ 1.4 kΩ, max plate voltage 400 V, max plate dissipation 25 W, heater 4 V / 2 A.

Is the CV1040 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the CV1040 as Rare 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 CV1040 sound like?

British military DHT.. 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

←CV1040

← CK6688 CV1936 →Compare → PX25

CV1040 Triode Vacuum Tube

Triode4V / 2AUX-4SPICE

SourceEML PX25 / Mullard.org CV1040 (= PX25)Reviewed2026-05-29StatusDataModelCalcModelNorman KorenPDF

Power triode delivering 25W for push-pull and SET designs

Datasheet ↗SPICE

CV1040 — GEC/MOV — triode vacuum tube — (1940)

1.4kΩ

7.0mA/V

10.0pF

13.0pF

6.00pF

GAIN10%

POWER63%

DRIVE99%

LINEARITY95%

SPECIFICATIONS

Heater4 V · 2 A

Max Plate Voltage400 V

Pa max25 W

Gain Factor10

gm7 mA/V

rp1.4 kΩ

Inter-electrode capacitances

Cgk10 pF

Cgp13 pF

Cpk6 pF

PinoutUX-4

Era1940

RarityRare

HEATER4V / 2A

MAX PLATE400V / 25W

BASEux4

Source datasheets

1 manufacturer datasheets cross-checked for CV1040

1 verified

TYPICAL OPERATING POINT

Va350V

Ia66.7mA

Vg-24.801854V

Pd23.34W

RL3kΩ

Av16.6dB

EXECUTIVE SUMMARY

The CV1040 is a directly-heated triode from GEC/MOV, introduced around 1940. It provides a gain factor (μ) of 10 with 1430Ω plate resistance. Commonly used in power (set) applications. British military DHT.

APPLICATIONS

SET outputPush-pull outputHeadphone output

Generic triode power (set) stage

• Hi-Fi stereo• Headphone amp

VS PX25

μ 0%Rp +13%Pd 0%Full comparison →

HISTORY

Introduced1940ManufacturerGEC/MOV

Pre-War