What is the VT-104 vacuum tube?

The VT-104 is a triode vacuum tube designed for preamp applications. Military designation..

What is a VT-104 substitute or equivalent?

Direct equivalents to the VT-104 include 12SQ7. 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 VT-104?

Amplification factor μ ≈ 5, transconductance gm ≈ 3.4 mA/V, plate resistance rp ≈ 1.7 kΩ, max plate voltage 1250 V, max plate dissipation 100 W, heater 10 V / 3.25 A.

Is the VT-104 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the VT-104 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 VT-104 sound like?

Military designation.. 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.

VT-104 Triode Vacuum Tube

Also known as 12SQ7

Power triode delivering 100W for push-pull and SET designs

TriodeHeater 10 V · 3.25 AOctalRCA 1942

Plate dissipation: 100W
Max plate voltage: 1250V
Transconductance: 3.4mA/V

VT-104

Characteristics

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

HeaterIndirectly heated

Specifications of VT-104 — Heater
Heater voltageVh	10 V
Heater currentIh	3.25 A

Limiting valuesDatasheet maximum ratings — not to be exceeded

Specifications of VT-104 — Limiting values
Plate voltageVa max	1250 V
Plate dissipationPa max	100 W

Mechanical

Specifications of VT-104 — Mechanical
Base	Octal
Rarity	Rare
Pinout

Small signalDatasheet parameters at the reference operating point — not limits

Specifications of VT-104 — Small signal
Transconductance	3.4 mA/V
Plate resistance	1.7 kΩ
Amplification factor	5

Capacitances

Specifications of VT-104 — Capacitances
Grid–cathode	5 pF
Grid–plate	13.5 pF
Plate–cathode	3.5 pF

Charactereditorial reading, not a measurement

Specifications of VT-104 — Character
Gain	5%
Power	100%
Drive	98%
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
Voltage amplifier
Headphone output

Generic triode preamp stage

Hi-Fi stereoHeadphone ampPA/public address

Replace or compare

Sources

By Jean-Michel Falligan DevergneReviewed May 29, 2026Source : amplifiedparts 12SQ7 (= VT-104)Active model : Norman Koren

Manufacturer datasheets

3 manufacturer datasheets cross-checked for VT-1043 verified

VT-104 DatasheetLocal mirror · PDF

SPICE models

Revision and verification status

Source: amplifiedparts 12SQ7 (= VT-104)
Reviewed: 2026-05-29
Status: DataModelCalc
Model: Norman Koren

Context

The VT-104 is a indirectly-heated triode from RCA, introduced around 1942. It provides a gain factor (μ) of 5 with 1700Ω plate resistance. Commonly used in preamp applications. Military designation.

History

Introduced: 1942
Manufacturer: RCA
Era: Pre-War

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