Not just a replacement, but an improvement!

EML 2A3-Mesh
EML 2A3-Mesh-V4


This tube is a plug & play, direct replacement for original the RCA 2A3 mono plate tube.   It features a mesh window in the plates.  This combines the electrical stability of solid plate tubes, with the non-resonance mesh material. We think this is the most ideal combination for a low power audio tube. 


The first owner can register the tube at the Emission Labs website, to participate in the 5 years guarantee program.

Sound Character of the EML 2A3-mesh  

When a tube is given mesh plates, something magic happens to the sound.  We believe this is caused by the high damping properties of the mesh material.  When using mesh tubes, you will experience what people call a more "transparent" sound stage, meaning a more realistic stereo reproduction of the original sound recording.  With this quality product you will enjoy the very best of what small triodes have to offer. 

The EML EML 2A3-Mesh  tube is constructed for lowest microphonics. All critical parts, like filaments and  grids  are made of hard metal for higher reliability and reproducible quality.  The tube base is now glued on the glass with anti-vibration rubber.

We have two versions for the heater: Normal heater, or Center Tapped heater.


With the center tap connected tubes, we enter a new field of applications. This has not been done before with Audio tubes. When biasing a DHT tube there is no cathode to connect something to. The cathode must be artificially constructed, by a resistor network. Since many years, all EML tubes already feature a center tapped heater, which is a way to enforce better electrical field geometry. Only, to this center tap there was never an electrical connection. So to the tube itself we had to make no changes. To the center tap of the heater, is now connected a wire, which becomes the third connection to the heater. Now the tube has five wire connections, and for this reason we can not use the 4 Pin UX4 base any more. We have chosen for the Octal base. It must be said, the V4 is a very special tube, which fulfills the needs of Circuit Design purists the best possible way. Depending on how you do it, you can enter new design fields, or you may choose to connect the center tapped tubes just the classical way. Even so, for tube testing you can ignore the center tap, and just connect the tube the regular (four pole) way. In that case, the EML1605-V4 will behave like a standard four pole tube. In the case you own center tapped tubes, but you whish to connect them like a non-center tapped tube, this is possible too. In that case just do not connect the center tap.

Here is a link to Application Note 06, describing the center tapped tubes in general. Link here.

Recommended transformers

Single Ended: LL1623-60mA (Wire secondary for ALT B, C, D for : 4, 8, 16 Ohms in this order)
Single Ended: LL1664-60mA (Secondary 8 Ohms)

Parallel Single Ended: LL1627-140mA (Wire secondary for ALT B, C, D for : 4, 8, 16 Ohms in this order)

Push Pull LL1620-PP (Wire secondary for ALT C, D, E for : 4, 8, 16 Ohms in this order)
Push Pull LL1620-PP-CFB (with optional 25% Cathode feedback winding)

Complete list of recommendations here


  • Gold plated Grid (Note8)
  • Gray Wire Mesh
  • Soft rubber suspended tube base
  • Center tapped filament
  • Fully compatible to solid plate EML 2A3
  • Hard metal Construction (Note1)
  • Two extra large getters
  • Hand blown Glass bulb
  • Anti-microphonic plate- and grid  suspension
  • These tubes are shipped in a high quality dual box
  • Tube printing with real gold (metal),  red color is glass burned into the glass 
  • Machined, solid tube base pins for highest contact precision. YAMAMOTO tube sockets highly recommended. 
  • Gold plated pins,  black ceramic socket.  (White bottom.)
EML 2A3-Mesh  Filament Ratings
Filament Voltage 
2.5Volt (AC or DC)
Tolerance on filament voltage
Filament Current 
EML 2A3-Mesh Maximum Conditions
Plate Voltage 
Plate Current 
Plate Dissipation Continuous

Highest possible Grid to ground resistor, Single Ended.


Highest possible Grid to ground resistor, Push-Pull.

EML 2A3-Mesh Factory Test conditions 
Plate Voltage 
Plate Current
Grid Voltage

Typical application
Singe Ended (SE) Recommended operating point

All bias methods are possible

Plate Voltage 
Plate Dissipation 
Plate Current 
Grid Voltage 
Plate Impedance (Rp)
 800 Ohm 
Amplification Factor 
Transconductance (Gm)
Load Impedance (Ra)
 2500 Ohm
Power Output @ Ra = 2500k
3.5 Watt  

Typical application
Push Pull (PP) Recommended operating point
Auto Bias

Plate Voltage 
Plate Current at zero signal
(value is for one tube)
Cathode Resistor
(Common Resistor for one tube)
780 Ohms
Load Impedance (Raa)
5000 Ohm
Power Output @ Raa = 5k
10 Watt  

EML 2A3 tube curves. See Note 3

EML 2A3-Mesh Mechanical Data

Size including Socket
(but excluding pins)

147 x 60 mm

Weight of one tube:
140 Gram

Pin 1: Heater1
Pin 4: Heater2
Pin3: Anode (Plate)
Pin2: Grid

Standard UX4 Base

Size including Socket
(but excluding pins)
147 x 60 mm

Weight of one tube:
140 Gram

Pin 1+2: Heater1
Pin 6+7: Heater2
Pin 8: Center Tap (Cathode)
Pin3: Anode (Plate)
Pin5: Grid
Pin4: Not on tube base

Special Octal Base, V4 Version
Shipment weight for 
pair in gift box: 730 Gram

Notes revised

  • Note 1) Hard-metals like  Molybdene and Wolfram are used in EML tubes. Though these metals are costly to use and to buy,  than classical tube nickel.  At critical places, we use hard metal for  geometry. This results in best tube parameters, also after shipment.   Though of course the tubes are glass items, you will still find EML tubes mechanically much more stabile than comparable tubes on the market.  
  • Note 2) Individual Test data, such as: Matching Data, Grid Current, Vacuum, Filament Current, etc., are on the Certificate that is on the outside of the tube box. Each tube is numbered from the inside, with a metal Tag
  • Note 3) Plate Curves: Made with the Sofia Digital Curve tracer.
  • Note 6. Some competitors claim to be the only one with a center tapped filament, but this is not true.   At EML we build since approximately 2005 all triodes center tapped, not just the 300B.    Such tubes which we offer in V4-Version have an electrical connection to the center tap.  Thus offering a real cathode connection. 
  • Note 7) Some people experiment with lower filament voltage, to expect better lifetime. This is essentially wrong to do.  If  the magic was that easy, we would make the tubes like this ourselves. The specified filament voltage is the one for best lifetime.  
  • Note 8) Gold plated grids have a few advantages. Amongst other this will give better bias stability of the tube, some protection against accidental overload, and better linearity of tube curves.
  • Note 10) Some competitors offer what they call "Mesh" tubes, which are no mesh tubes at all, but only give the optical illusion of this. See our warning page for FAKE Mesh tubes..

Type EML 2A3-Mesh 

High. Res.Images: 
Front - Side 
Gold Grid

EML EML 2A3-Mesh
Standard UX4 Base

EML 2A3-Mesh V4
Special Octal Base.
(see the main text)

Compatible to 6S4S
but 6S4S has 6.3V heater

Subscribe or unsubscribe our Mailing List
© Emission Labs. All Rights Reserved