What is the 45B-EmissionLabs vacuum tube?

The 45B-EmissionLabs (45B EML) is a triode vacuum tube designed for power (set) applications. Enhanced Type 45..

What is a 45B-EmissionLabs substitute or equivalent?

Direct equivalents to the 45B-EmissionLabs include 45. 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 45B-EmissionLabs?

Amplification factor μ ≈ 3.5, transconductance gm ≈ 2 mA/V, plate resistance rp ≈ 1.8 kΩ, max plate voltage 450 V, max plate dissipation 22 W, heater 2.5 V / 2.5 A.

Is the 45B-EmissionLabs still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 45B-EmissionLabs 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 45B-EmissionLabs sound like?

Enhanced Type 45.. 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 10, 2026

←45B-EmissionLabs

← 45 46 →Compare → 45

45B-EmissionLabs 45B EML Triode Vacuum Tube

Triode2.5V / 2.5AUX-4

SourceEmission Labs design notes (EML-12B-20A-20B-30A) · external audit feedbackReviewed2026-05-10StatusDataModelCalcModelunder reviewPDF

High-power directly-heated triode for single-ended amplification

Datasheet ↗

45B EML — Emission Labs — triode vacuum tube — (2008)

3.5

1.8kΩ

2.0mA/V

6.0pF

8.0pF

3.50pF

GAIN4%

POWER55%

DRIVE98%

LINEARITY95%

SPECIFICATIONS

Heater2.5 V · 2.5 A

Max Plate Voltage450 V

Pa max22 W

Gain Factor3.5

gm2 mA/V

rp1.8 kΩ

Inter-electrode capacitances

Cgk6 pF

Cgp8 pF

Cpk3.5 pF

PinoutUX-4

Era2008

RarityModerate

HEATER2.5V / 2.5A

MAX PLATE450V / 22W

BASEux4

EXECUTIVE SUMMARY

The 45B-EmissionLabs is a directly-heated triode from Emission Labs, introduced around 2008. It provides a gain factor (μ) of 3.5 with 1750Ω plate resistance. Commonly used in power (set) applications. Enhanced Type 45.

APPLICATIONS

SET outputPush-pull outputHeadphone output

Generic triode power (set) stage

• Hi-Fi stereo• Headphone amp

VS 45

μ -12%Rp +9%Pd +120%Full comparison →

HISTORY

Introduced2008ManufacturerEmission Labs

Modern

45B-EmissionLabs 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.

SIMILAR TRIODES

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01APreamp 100THTransmitting (SET)101DPower (SET)10YPower (SET)12AT7Driver 12AU7Line / Headphone 12AX7Preamp 12AY7Preamp