300B Data Sheet

Description

2A3 Mesh tube

This tube is a direct replacement for the Western Electric E300B as build until 1988. Glass height and diameter are the same.

High Resolution

Guarantee program for first owner.

At EML we have the normal guarantee. In addition to that, the first owner can register the tube within 4 weeks after receival, at the Emission Labs 搴恮ebsite, to participate in the 5 years guarantee program.

Our Guarantee conditions


Register here for the 5years guarantee


Features

  • Gold Anoded Grid(Note8)
  • Soft rubber suspended tube base
  • 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
  • Machined, solid tube base pins for highest contact precision. YAMAMOTO tube sockets highly recommended.
  • Gold Anoded pins,black ceramic socket.(White bottom.)

Sound Character of the EML 300B

It is the most asked question, and for this we refer to the one and only genuine 300B, as made until 1988 by Western Electric in the Hawthorne plant in Cicero, Illinois, USA. (So definitely not the later USA made replicas under WE brand, from 1997 onwards).

The 300B tube has less interaction with the speaker system as smaller tubes like the 45 will have. This makes the sound character less dependant on the speakers, and for that reason quite dependant on the tubes itself. We see 300B often used with medium efficiency loudspeakers. Meaning, the tube often needs to work relatively hard, which is indeed what it is designed for.

However, a Single Ended, no-feedback amplifier can not combine highest output power with lowest distortion. The user often comes into a situation where relatively high output power, still requires relatively low distortion. Moreover, distortion should increase as little as possible, during the aging process, and lifetime should be high by itself, even though this tube is loaded often quite hard by the amplifier. All in all, these are not the easiest specifications for a tube in general.

At EML we have contributed to this, by extremely low hum and low distortion of our 300B tubes, over the major part of the lifetime. This is done by our unique filament and grid construction, featuring a real, physical filament center tap, positioned outside of the grid, but inside the glass bulb. We use not only gold grid wire, but we completely gold Anode the grid, after it is made. The clean, gold Anoded surface increases bias stability, and good matching between two tubes of a pair stays constant like this over the full lifetime of a pair.

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

EML 300B Filament Ratings
Filament Voltage
= 5 Volt (AC or DC)
Tolerance on filament voltage
4%
Filament Current
~ 1.3 Ampere

 

EML 300B Maximum Conditions
Anode Voltage
350Volt
Anode Current
70mA
Anode Dissipation Continuous
17Watt

Highest possible Grid to ground resistor, Single Ended.

250kOhm

Highest possible Grid to ground resistor, Push-Pull.

50kOhm

 

EML 300B Factory Test conditions
Anode Voltage
300V
Anode Dissipation
17Watt
Anode Current
56mA
Control Grid Voltage
-58Volt DC
Anode Impedance
700 Ohm
Amplification Factor
3,9
Transconductance
5.6 mA/V
Control Grid Voltage
matched
Transconductance
matched

 

300B Recommended Single Ended operating points. Other choices are possible.

Anode (V)
vs. Heater

Grid

(V)

vs. Heater

Anode Current (ma)
Anode Rp (Ohm)

Load

(Ohm)

Power

Output

Watt)

ower

Output

Watt)

2nd harm.
(dB)
350
-74
60
720
2000
21
10.2
21
350
-74
60
720
3000
21
8.3
26
350
-74
60
720
4000
21
7.0
30
350
-71
80
640
2200
28
9.6
26
400
-74
60
720
3500
24
10.5
26
400
-74
80
720
2500
32
12.5
25
450
-100
60
780
4000
27
12.5
26
450
-100
60
780
5500
27
10.0
30
450
-98
73
720
2000
33
16.2
21
450
-98
73
720
3000
33
13.2
25
450
-98
73
720
4500
33
10.5
30

450
-97
80
700
2000
36*
17.8
21
450
-97
80
700
3000
36*
14.6
26
450
-97
80
700
4500
36*
11.5
31

* Lifetime gets less at 36 Watt dissipation, regardless of the tube brand. For best lifetime, it is recommended to stay below 33 Watt. For highest output power and no compromise with lifetime or distortion, it recommended to choose the 300B-XLS.

Choice of output transformer impedance: For each working point, a wide range of primary impedance is possible. When using a transformer of another value, you can estimate the output power and distortion by averaging between two rows of this table. Example: 450V, 60mA. Use of Lundahl LL1679-70mA (4k5 type). This will give you appr. 11.5 Watt @ 27dB 2nd harmonics. (28dB distance of signal to 2nd harmonics.

Curves of 2A3 tube

EML 300B tube curves. See Note 3

300B Anode Curves Print Version (full size pdf)

Download these curves as PTE file

What is a PTE file?

Some recommended Lundahl transformers
  Primary
Secondary
Auto Bias Cathode resistor
Anode Current Anode Voltage to ground
LL1623-090mA
11Hz @1.5dB
3000Ω Alt.B = 4Ω
Alt.C = 8Ω
Alt.D = 16
750 Ohms 80mA 435V

LL1664-080mA
13Hz @1.5dB

3000Ω 750 Ohms 80mA 435V

 

EML 300B Mechanical Data

Size including Socket
(but excluding pins)

148 x 65 mm

Pin 1: Heater1
Pin 4: Heater2
Pin2: Anode
Pin3: Grid

Weight of one tube:
145 Gram

Shipment weight for pair in gift box:
840 Gram

UX4 Base

 

Notes

Note1) Hard-metals can be used in electron tubes, though these are more difficult to use, and more costly than the classical nickel. Hard metal Anodes have a more precise Anode distance, and do not change shape when heated, or at mechanical shock. This ensures reproducible tube parameters, and long term stability. Wolfram grids allow the most precise grid wire distance, because wolfram is an extreme hard metal. Best grid geometry ensures uniformity and linearity of the tube curves.

Note2) 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

Note3) Anode Curves: Made with the Sofia Digital Curve tracer. Anode curves with courtesy of AMR

Note4) We are recommending the same values as Western Electric in their 1950 Data sheet.

Note5) The Western Electric 1950 Data sheet. says 36 Watt maximum dissipation. Later data sheets say 40 Watt. Though 40 Watt is possible, this is a peak value only, and no normal working point. When you intent to get the "maximum" out of a 300B, and operate this tube at the limits of safe operation, it is a better idea to use the 300B-XLS in such a case.

Note6) Some of our competitors claims to be the only one with a center tapped filament, but this is not true. At EML we build since many years all triodes center tapped, not just the 300B.

Note7) Don't experiment with lower filament voltage, to expect better lifetime. If it was that easy, we would make them like this ourselves. The specified filament voltage is the one for best lifetime.

Note8) Gold Anoded grids have a few advantages, such as increased bias stability, some protection against accidental overload, and better linearity of tube curves.

Note9) The curves for the 300B are plotted, with AC heating. This is in accordance with the historical WE data sheet.