300B Data Sheet
Description
This tube is a direct replacement for the Western Electric E300B as build until 1988. Glass height and diameter are the same. |
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.
Register here for the 5years guarantee
Features
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Gold Plated Grid (Note)
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Soft rubber suspended tube base
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Hard metal Construction (Note)
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Extra large getters
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Hand blown Glass bulb
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Anti-microphonic Anode- and grid suspension
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These tubes are shipped in a high quality dual box
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Tube printing with 24k gold, and red color burned into the glass
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Gold Plated pins, black ceramic socket.(White bottom.)
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, Cicero, USA, and not to the new production USA made 300B.
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 Cathode 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 |
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Filament Voltage |
= 5 Volt (AC or DC) |
Tolerance on filament voltage |
-4... +5% |
Filament Current |
~ 1.3 Ampere |
Maximum Time on Stand By (Heater voltage only) | 2 hours |
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EML 300B Factory Test conditions |
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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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EML 300B tube curves. See Note 3
300B Anode Curves Print Version (full size pdf)
Some recommended Lundahl transformers |
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Primary |
Secondary |
Auto Bias Cathode resistor |
Anode Current |
Anode Voltage to ground |
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LL1623-090mA 11Hz @1.5dB |
3000Ω |
Alt.B = 4Ω Alt.C = 8Ω Alt.D = 16Ω |
750 Ohms |
80mA |
435V |
Alternative: Use transformer Impedance Boards for LL1623 by JACMUSIC. EE16 switches between 4 and 8Ohms at 3k. EE18 switches between 8 and 16Ohms at 3k. |
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LL1664-080mA |
3000Ω |
8Ω |
750 Ohms |
80mA |
435V |
Complete list of recommendations here |
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EML 300B Mechanical Data |
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Size including Socket 148 x 65 mm Pin 1: Heater1 Weight of one tube: Shipment weight for pair in gift box: |
Notes
- 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.
- 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
- Average Plate Characteristics are made with the Sofia Digital Curve tracer.
- We are recommending the same values as Western Electric in their 1950 Data sheet.
- 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.
- Some of our competitors claims to be the only one with a Center Tapped filament, but at EML we build since many years all tubes Cathode Tapped, not just this tube.
- Do not experiment with lower filament voltage, to expect better lifetime. If it was that easy, we would make the tubes like this ourselves. The specified filament voltage is the one for best lifetime.
- Gold Plated grids have a few advantages, such as increased bias stability, some protection against accidental overload, and better linearity of tube curves.
- The curves for the 300B are plotted, with AC heating. This is in accordance with the historical WE data sheet.