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Emission Labs EML AD1M Mesh Plate Heater Current 1.5A Type Matched Pair

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Emission Labs EML AD1M Mesh Plate Heater Current 1.5A Type Matched Pair

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Almost same standard as Telefunken AD1

AD1 is the highlight of the European DHT triode


AD1/350 was Telefunken's designation for a high-quality version of the AD1 that can replace any AD1 with a conventional 250V operating point, but can also operate up to 350V. It allows forAdditionaloutput power, but with no increase in losses. This higher operating point works initially in the historical version, but the tube may generate unexpected grid currents.However, the EML AD1/350 is completely free from grid current at any operating point, even during periods of high usage.

Gray wire mesh anodes mounted on a rigid metal frame for maximum stability

Although not electrically identical, the existing 2A3 schematic can be used provided that a 4 volt heater voltage is available.

Sound character of AD1

The high heater voltage of 4 volts is another source of sound. This effect is only true for directly heated tubes; the AD1 is less dominant than the 2A3 and sounds silky; all 4-volt DHTs from the 1930s through the 1940s have very high collector value.

Tube socket for AD1

The original P8 "side contact" socket was developed by Philips. This socket has an interesting property: it automatically pulls the tube into the socket. For this to work well, the dimensions of the tube base, the dimensions of the socket, and the shape of the socket spring must be accurate. It should be noted that other manufacturers' P8 sockets manufactured in recent years are less than ideal and may be in poor shape; EML uses vintage tube bases from the 1930s to manufacture the AD1.

  • Gray wire mesh anodes mounted on a rigid metal frame for maximum stability.
  • Gold plate, Wolfram Grid.
  • Soft Rubber Suspended Tube Base
  • Cathode Tap Filament
  • Slow-start filaments for maximum life
  • Anode voltage up to 350V
  • Continuous use with maximum anode dissipation
  • Carbide alloy construction.Philips and Tungsram's historic AD1 vacuum tubes often develop grid current and gas problems after the first 500 hours of use. In contrast, EML tubes have excellent tube bias stability and grid currents well below 1uA.
  • Tubes printed with real gold (metal), the red color is glass baked into the glass.

EML AD1 Filament Rating

Filament Voltage 4V (AC or DC)
Filament voltage tolerance +5% / -2.5%
Filament current 1.5 Am
Maximum standby time (heater voltage only) 2 hrs


EML AD1 maximum conditions (Not allowed at the same time)

Anode voltage 350V
Anode current 60mA
Anode consumption fixed bias (continuous) 15W
Anode dissipation Auto bias (continuous) 18W
Maximum grid/ground resistance, single-ended:Auto Bias 500 kΩ
Maximum grid/ground resistance, single-ended: fixed bias 50kΩ