2A3-Mesh Data Sheet

Description

2A3 Mesh tube

The EML 2A3 mesh tube is a plug & play, direct replacement for original the RCA 2A3 tube. It features a mesh window in the Anodes. This combines the mechanical stability of Solid Plate tubes, with the properties mesh materia, which is soft, and has a resonance damping function. We think this is the most ideal combination for a low power audio tube.

Click here for High Resolution image

Guarantee program for first owner.

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

Sound Character of the EML 2A3-mesh

When a tube is given mesh Anodes, something magic happens to the sound. We believe this is caused by the high damping properties of the wire 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 2A3-Meshtube 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.

Where 2A3-Mesh is not advised:
  • Mesh tubes used as output tubes in a separate pre amplifier, or used in a head phone amplifier, may occasionally cause a spurious noise. Though this is rare, it is not a tube issue when it happens. Otherwise we recommend the EML solid plate tubes.
EML 2A3-Mesh Filament Ratings
Filament Voltage
2.5Volt (AC or DC)
Tolerance on filament voltage
Also read our TB-05
4%
2.4 ... 2.6V at Tube pins
2.5 ... 2.7V at Socket pins
See also the Note about Heater Voltage
Filament Current
2.5Ampere
.
EML 2A3-Mesh Maximum Conditions
(not possible simultaneously)
Anode Voltage
350Volt
Anode Current
70mA
Anode Dissipation Continuous
18Watt
Highest possible Grid to ground resistor, Single Ended, Auto Bias. (See Notes 8, 11)
500kOhm
Highest possible Grid to ground resistor, Single Ended, Fixed Bias. (See Notes 8, 11)
50kOhm
.
EML 2A3-Mesh Factory Test conditions
Anode Voltage
250V
Anode Current
60mA
Control Grid Voltage
as needed for 60mA
Transconductance
tested at 60mA
.
Typical application
Singe Ended (SE) Recommended operating point
All bias methods are possible
Anode Voltage
250V
Anode Dissipation
15Watt
Anode Current
60mA
Control Grid Voltage
-45Volt
Anode Impedance (Rp)
800 Ohm
Amplification Factor
4,1
Transconductance (Gm)
5,2mA/V
Load Impedance (Ra)
2500 Ohm
Power Output @ Ra = 2500k
3.5 Watt
.
Typical application
Push Pull (PP) Recommended operating point
Auto Bias
Anode Voltage
300V
Anode Current at zero signal
(value is for one tube)
40mA
Cathode Resistor
(Common Resistor for one tube)
780 Ohms
Load Impedance (Raa)
5000 Ohm
Power Output @ Raa = 5k
10 Watt
Curves of 2A3 tube
EML 2A3 Average Plate Characteristics. 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
Pin2: Anode
Pin3: Grid

UX4 Base
(Standard)

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
Pin5: Grid
Pin4: Not on tube base

Octal Base
(V4 Version)
Shipment weight for pair in gift box:
730 Gram
Features
  • Gold Plated Grid (Note8)
  • Gray Wire Mesh
  • Soft rubber suspended tube base
  • Center tapped filament version available (order V4-Version)
  • Electrically compatible to vintage 2A3 tube by RCA.
  • Hard metal Construction (Note1)
  • Two extra large getters
  • Hand blown Glass bulb
  • Anti-microphonic Anode- 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
  • YAMAMOTO tube sockets highly recommended.
  • Gold Plated pins,black ceramic socket.(White bottom.)
Notes

Note 1) Hard-metals like Molybdenum and Wolfram are used in EML tubes. Though these metals are more costly to use and to buy, than classical tube nickel. At critical places, we use hard metal for better geometry. This results in best tube parameters, also after shipment. 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) Average Plate Characteristics are 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) Heater Voltage: 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. Under Heating can lead to early loss of emission, though new EML tubes will fully recover once the heater voltage is corrected, older tubes will recover only partially. The specified filament voltage at 0% tolerance is the one for best lifetime. The voltage we specify, is at the TUBE PINS itself. Any voltage drop by the socket contacts must be compensated for. For 2A3 tubes, some sockets have 50mV voltage drop per pin, because the heater current of 2.5 Ampere is very high. Causing a total drop of 0.1V for both pins together. So a voltage of 2.6Volts at the socket pins is needed, to make sure there is minimum 2.5 Volts at the tube pins. If operated at 2.5V at the SOCKET Pins, this is the lowest limit, because at the TUBE Pins this means only 2.4V, at the lowest end of the tolerance, thus not achieving the highest 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, better linearity of tube curves, and much reduced grid current.

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.

Note 11) These grid current values are the original RCA specifications, which EML also meets and guarantees. Though it can be observed that often significant higher values seem possible with old or new tubes, please keep well in mind, that the grid current creates a voltage across the grid resistor. This is a DC current, coming "from" the grid. So, the polarity of this voltage will off-bias the tube such that plate current will increase, above the intended value. In some bad cases, leading to thermal destruction of the tube. For this reason, manufacturers specify a maximum grid resistor, which value has to do with the quality of the whole tube, including clean materials, best vacuum, and safe thermal design. When tubes are new, grid current is usually at it's lowest. In order to operate safe, during the entire lifetime of the tube, these grid resistor values were specified by RCA. We adopted those values at EML, in order to prevent amplifier designers to build products around the (much better) EML specifications, but then historical tubes may sometimes fail in such an amplifier. Understanding this consequence, EML 2A3 may be used with 2x higher grid value resistors as RCA specified. So 1 Meg for Auto bias, and 100k for fixed bias. Grid current of factory new tubes is below 1uA. Rejection level for faulty, used tubes is above 3uA at 250V/60mA, and full warm up.