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.

CV1040 Triode Vacuum Tube

Also known as PX25

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

TriodeHeater 4 V · 2 AUX-4GEC/MOV 1940

Plate dissipation: 25W
Max plate voltage: 400V
Transconductance: 7mA/V

CV1040

Characteristics

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

HeaterDirectly heated

Specifications of CV1040 — Heater
Heater voltageVh	4 V
Heater currentIh	2 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of CV1040 — Limiting values
Plate voltageVa max	400 V
Plate dissipationPa max	25 W

Mechanical

Specifications of CV1040 — Mechanical
Base	UX-4
Rarity	Rare
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of CV1040 — Small signal
Transconductance	7 mA/V
Plate resistance	1.4 kΩ
Amplification factor	10

Capacitances

Specifications of CV1040 — Capacitances
Grid–cathode	10 pF
Grid–plate	13 pF
Plate–cathode	6 pF

Charactereditorial reading, not a measurement

Specifications of CV1040 — Character
Gain	10%
Power	63%
Drive	99%
Linearity	95%

datasheet cited · model or editorial reading · catalogue value, no citation attached yet · nothing invented

Using this tube

Applications

SET output
Push-pull output
Headphone output

Generic triode power (set) stage

Hi-Fi stereoHeadphone amp

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : EML PX25 / Mullard.org CV1040 (= PX25)Active model : Norman Koren

Manufacturer datasheets

1 manufacturer datasheets cross-checked for CV10401 verified

CV1040 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: EML PX25 / Mullard.org CV1040 (= PX25)
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Norman Koren

Context

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.

History

Introduced: 1940
Manufacturer: GEC/MOV
Era: Pre-War

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