EML 300B-Mesh Data Sheet
long Anode version

Description

2A3 Mesh tube

The 300B-Mesh can replace a standard 300B-Mesh in several cases, but not in all cases. So please read this data sheet carefully.

Do not simply plug & play a 300B-Mesh instead of a 300B-Mesh. Overheated anodes may result if you do not check the following conditions, and such a damage is not covered by the guarantee.

High Resolution

The 300B-Mesh mesh can replace a normal 300B-Mesh tube, if the following conditions are met:
  1. Bias and Anode dissipation must be reduced from 22 Watt to absolute maximum 28 Watt. (see below table)
  2. Filament current of minimum 1.4 Ampere can be supplied
  3. The larger length of the tube is no problem. (like with closed amplifiers)

The 300B-Mesh mesh is a 'long Anode' version,. The Anodes are 25% longer as with normal 300B-Mesh we build. The physical size of this tube, inside and outside is the same as the larger 520B tubes we make, so it is much larger than you may expect from a 300B-Mesh. Check the dimensions at the end of this Data sheet.

The heat dissipation of the wire mesh is lower than for Solid Plate anodes. So the maximum Anode dissipation of the 300B-Mesh Mesh for continuous use must be limited to typical 22Watt, or absolutely maximum 28Watt. This is however a classical use condition in several Japanese products. Though many other amplifiers exceed this number, so it is important to check with your amplifier manufacturer first, if you are not sure about the Anode dissipation.

Guarantee program for first owner.

The first owner can register the tube within 4 weeks after receival, at the Emission Labs ® website, to participate in the 5 years guarantee program, which is additional to the legal obligations of the seller.

Our Guarantee conditions


Register here for the 5years guarantee


Features

Sound Character of the EML 300B-Mesh-Mesh tube

Why Mesh Anodes? When a tube is given mesh Anodes, something magic happens to the sound! We believe this is caused by the better damping properties of the wire mesh material.  A Solid Plate anode due to it's circular construction will have quite some ringing (bell like effect). A mesh anode will not have this effect. In most cases, when using mesh tubes, you will experience a more transparent sound stage, meaning a more realistic stereo reproduction of the original sound recording. With mesh tubes you will enjoy the very best of what small triodes have to offer. 

Note: mesh means woven metal wire. Chinese factories make a tube with punched Anodes, and for marketing call this 'mesh'. A punched Anode from solid metal will also have this ringing effect, and can never have the superior resonance damping properties a wire mesh tube has.

 

EML 300B-Mesh Filament Ratings

Filament Voltage

Important: See notes at page bottom

= 5 Volt (AC or DC)
Tolerance on filament voltage
4%
Filament Current
~ 1.4 Ampere

.

300B-Mesh Mesh Maximum Conditions
 
Maximum current and maximum voltage not possible simultaneously
Anode Voltage 
450Volt 
Anode Current 
80mA 
Peak Anode Dissipation
28Watt 

Grid resistor @ Anode Dissipation= 22 Watt

100k...350kOhm
Grid resistor @ Anode Dissipation= 24 Watt
100k...250kOhm
Grid resistor @ Anode Dissipation= 26 Watt
100k...140kOhm
Grid resistor @ Anode Dissipation= 28 Watt
100kOhm, or lower

.

300B-Mesh Mesh Recommended Single Ended operating points
Anode Voltage
Control Grid Voltage
Anode Current (ma)
Anode Rp (Ohm)
Load
(Ohm)

Anode Dissipation (Watt)

Power Output (Watt)
2nd harm.
(dB)
350
-73
63
720
2000
22
10.6
21
350
-73
63
720
3000
22
8.7
26
350
-73
63
720
4000
22
7.3
30
350
-72
70
685
3000
24
8.5
28
.
400
-74
60
720
3500
24
10.5
26
.
440
-101
59
775
4000

26

12
26
440
-101
59
775
5500
26
9.6
30

* For best lifetime, it is recommended to choose maximum 26 Watt Anode dissipation, though 28 Watt is possible at some compromise with life time. If you need higher output power than 300B-Mesh can do, choose standard 300B-Mesh, or upgrade to 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.

.

EML 300B-Mesh 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-Mesh 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)

POwer

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.

 

EML 300B-Mesh tube curves. See Notes

300B-Mesh Anode Curves Print Version (full size pdf)


Download these curves as PTE file


What is a PTE file?

Some recommended Lundahl transformers for the 300B-Mesh
 
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 = 16Ω
750 Ohms
80mA
435V

LL1664-080mA
13Hz @1.5dB

3000Ω
750 Ohms
80mA
435V

 

EML 300B-Mesh Mechanical Data

UX4 Base

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

 

Notes

  1. 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.
  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
  3. 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.
  4. Gold Plated grids have a few advantages, such as increased bias stability, some protection against accidental overload, and better linearity of tube curves.
  5. Heater voltage is always defined at the tubes pins itself. There may be some voltage drop along the wires, and tube contacts as well. So voltage measured at the tube socket wiring should be 5.1V.