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 © website, to participate in the 5 years guarantee program.

Our Guarantee conditions


Register here for the 5years guarantee


Features

Sound Character of the EML 300B

It is probably the most asked question, and for this we refer to the one and only genuine 300B, as made until 1988 by Western Electric itself, in the Hawthorne plant in Cicero, Illinois, USA. We do NOT refer for this to new made replicas, by a USA company, from 1997 onwards.

The 300B tube has less interaction with the speaker system, as smaller tubes like the 45 have. This makes the sound character less dependant on the speakers, and for that same reason more 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 the 300B is designed for.

However, a Single Ended, no-feedback amplifier can not combine highest output power with lowest distortion. The user will 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. Add to this, lifetime expectations are high by itself, even though this tube is loaded often quite hard by the amplifier. Though 300B is strong, these are still no easy 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 Plate the grid, after it is made. The clean, gold Plated surface increases bias stability, and good matching between two tubes stays constant like this over the full lifetime.

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

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

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300B Recommended Single Ended operating points. Other choices are possible.
Anode vs. Heater (Volt)
Grid
(V)
vs. Heater
Anode Current (mA)
Anode Rp (Ohm)
Load (Ohm)
Anode Dissipation (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 of 300B reduces 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 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 = 16Ω
750 Ohms
80mA
435V

LL1664-080mA
13Hz @1.5dB

3000Ω
750 Ohms
80mA
435V
Complete list of recommendations here

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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

Notes