Not just an replacement, but an improvement!

EML 2A3-S

Uploaded: 15-Dez-2013

Description

This tube is a plug & play, direct replacement for original the RCA 2A3 mono plate tube. It is nicely designed for the same appearance too. The 2A3-S will bias exactly at the original operating point.  For those who whish to operate this tube at a higher power, this is also possible. You can go up to 28Watt Single-Ended, which will give 9.3 Watt RMS output signal. For best sound, it is recommended to use a normal 2A3 SE transformer,  and get the higher dissipation by increasing the plate voltage. 

You can  make a push-pull circuit that has a peak power dissipation of 40Watt per tube, at  full output signal. This will give 40Watt (or more) output signal. Without signal, the power dissipation needs to drop at 28Watt per tube. 

The EML 2A3-S  tube is constructed for low  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.

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

Features

  • Gold plated Grid
  • Soft rubber suspended tube base
  • Center tapped filament
  • Fully compatible to solid plate 2A3, but may be used at higher power as well
  • 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.)
 
Type 2A3-S
High. Res.Images:
Front - Top - Bottom
Curves
2A3-S  Filament Ratings
Filament Voltage 
2.5Volt (AC or DC) 
Tolerance on filament voltage
4%
Filament Current 
2.5Ampere 
.
2A3-S Maximum Conditions 
Plate Voltage 
400Volt 
Plate Current 
100mA 
Plate Dissipation Continuous
28Watt
Plate Dissipation Peak (30minutes)
40Watt
Power Output in Class A 
9.3 Watt 

Highest possible Grid to ground resistor, Single Ended.

250kOhm 

Highest possible Grid to ground resistor, Push-Pull.

50kOhm 
.
2A3-S Factory Test conditions
Plate Voltage 
250V 
Plate Current
60mA 
Grid Voltage
matched
Transconductance
matched
.
2A3-S Typical Data (1)
RCA 2A3 operating point
Plate Voltage 
250V 
Plate Dissipation 
15Watt 
Plate Current 
60mA 
Grid Voltage 
-45Volt 
Plate Impedance (Rp)
 800Ohms 
Amplification Factor 
 4,1 
Transconductance (Gm)
5,2mA/V 
Load Impedance (Ra)
 2500 Ohm
Power Output @ Ra = 2500k
3.5 Watt  
.

2A3-S Typical Data (2)
Safe operation point
for high power application

Plate Voltage 
375V 
Plate Dissipation 
28Watt 
Plate Current 
75mA
Grid Voltage 
-Volt 
Plate Impedance (Rp)
 745Ohms
Amplification Factor 
 4,1
Transconductance (Gm)
5,5mA/V 
Load Impedance (Ra)
 2250...3750 Ohm 
.
2A3-S Mechanical Data
Size including Socket
(but excluding pins)

175 x 60 mm
6.9 x 2.7 Inch

Tube weight
140Gram
Shipped weight for
double box with one pair
770Gram
.
  • Note 1)  Hard-metal filaments prevent filament breakage with DHT Tubes.  This material has a higher melting point than the classical nickel wires. Wolfram grids  allow the most precise grid wire distance, because wolfram is an extreme hard metal.   This ensures better grid  precision, which gives uniformity and better linearity at the low end of the tube curves.
  • Note 2)  Individual Test data, such as:  Matching Data, Grid Current, Vacuum, Filament Current, etc,  are on the Certificate that comes with each individual Tube.  Each tube is numbered, inside the bulb  with a metal Tag
  • Note 3)  Tube Curves:  Made on the The Sofia Curve tracer, with courtesy of AMR, Wisconsin, USA.

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