EML 300B-XLS, EML 300B-XLS V4. Data Sheet

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Description

Emission Labs 300B-XLS Electron tube

This tube has the classical grid construction and the tube curves of the 300B. It has the stronger Anode construction and larger glass of the vintage 52B however. So in one tube we have combined the very best of two classical products.

Front view


Side View

 

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

  • Gold Plated Grid(Note8)
  • Soft rubber suspended tube base
  • Hard metal Construction(Note1)
  • 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
  • YAMAMOTO tube sockets highly recommended.
  • Gold Plated pins,black ceramic socket.(White bottom.)

Sound Character of the EML 300B-XLS

For use in Single Ended amplifiers, the 300B-XLS is an ideal choice, because with those amplifiers good sound results from the right use of the tube, not over stressing the tube. This means the tube should not be working at the maximum electrical limits. Here we think the 300B-XLS is at it's right place, taking advantage of the higher electrical reserve this tube has. The 300B-XLS will reproduce the required loudness with more ease than the standard 300B. The result is a more transparent sound picture at low or medium volume, while at higher volume, the dynamics of the original recording will stay unaffected.

For use in Push Pull amplifiers, this tube is also an excellent choice, because this type of amplifier is hard on the tubes by definition. The 300B-XLS is made to deal with such conditions, and will allow the amplifier to play gently at low sound level, as well as reproduce higher sound level with the detail and precision you expect from a push pull amplifier.

Bias of the 300B-XLS

The 300B-XLS will bias in any amplifier the same way as the original WE300B. Sill it can be used in two ways if you want it. These two methods are explained here.

  1. It is possible to replace any 300B with this tube. Just plug it into any 300B amplifier, and the tube will set itself exactly to the original 300B working point. The EML 300B-XLS is a very strong tube, and it will develop the output power with more ease. Specially for amplifiers that let the 300B tubes work very hard, the EML 300B-XLS is the right product to choose. Any amplifier that is trying to get as much as possible power out of a normal 300B, will benefit from the 300B-XLS. Improved sound and longer lifetime will be the result.
  2. Another purpose of the EML 300B-XLS is to get more power, as would be possible with standard 300B tubes. This can only be done when there is the possibility to adjust the bias of the amplifier higher. If the Anode current of the tube is set ABOVE the standard 300B specifications, the tube will now move to a part of the curves with lower Anode resistance. This is a specialty of the 300B-XLS. This will give a better damping factor of the bass loudspeakers, resulting not in more bass, but in a more natural sound. Check our customer feedback section of the website!
  3. Alternatively the whole amplifier can be constructed around the 300B-XLS, of not only the anode current is increased, but also the supply voltage. A list of recommending working points is given, further down in this data sheet.

All critical parts, like filaments, grids and Anodes are constructed of hard metal for the best reliability and reproducible quality. 

We have two versions for the heater:

Normal heater with the UX4 Socket, or Cathode Tapped heater with an octal socket. Tubes with the Cathode Tapped heater have an additional electrical connection, and need an octal socket for this reason. The Cathode Tap, provides a REAL electrical cathode, which simplifies schematics, improves signal to noise ratio, increases tube output power and lowers distortion. Yet, if desired afterwards, these can always be used as regular 300B-XLS, by simply not connecting the Cathode Tap.


Normal UX4 Socket


V4-Version with Octal Socket

Here is a link to Application Note 06, describing the Cathode Tapped tubes in general.

Link to AN-06

 

Filament Ratings (See note 5) 
 

Standard tube
300B-XLS
4Pin Socket (UX4)

Cathode Tapped
300B-XLS V4
8Pin Socket (Octal)
Filament Voltage (AC or DC)
= 5 Volt
= 5.0V with Balanced Heater.
( 2x 2.5V )
Tolerance on filament voltage
5 %
5 %
Filament Current
~ 1.5Amp
~ 1.5Amp

.

EML-300-XLS Factory Test conditions
Anode Voltage
495V
Anode Current
100mA
Transconductance
6.2 mA/V

.

300B-XLS Recommended Single Ended operating points
(This is just a selection, other choices are possible)
Important: This table is for AUTO BIAS, with Cathode Resistor

Anode Voltage

(Against Heater)

Control Grid Voltage

(Against Heater)
Anode Current (mA)
Cathode Bias Resistor (Ohm)
Anode Rp (Ohm)

Gain
(mu)
Load
(Ohm)

Anode Dissi-pation
(Watt)

Power
Output (Watt)
2nd harm.
(dB)
AUTO BIAS. Lifetime is very high:
473
-72
60
1200
720
3.8
3500
24
11
27
473
-74
80
920
720
3.6
2500
32
13
26
AUTO BIAS. Lifetime is very high:
545
-100
60
1600
780
5.2
4000
27
13
26
545
-100
60
1600
780
5.3
5500
27
10
31
AUTO BIAS. Lifetime is very high:
545
-94
73
1300
720
4.1
2000
33
16
22
545
-94
73
1300
720
4.5
3000
33
13
26
545
-94
73
1300
720
4.9
4500
33
11
31
AUTO BIAS. Lifetime is very high:
545
-96
80
1200
700
4.2
2000
36
18
22
545
-97
80
1200
700
4.6
3000
36
15
26
545
-97
80
1200
700
4.9
4500
36
12
31
AUTO BIAS. Lifetime is high:
575
-99
90
1100
670
4.7
1900
43
21
23
575
-99
90
1100
670
5.1
2800
43
17
27
575
-99
90
1100
670
5.5
4200
43
14
32
AUTO BIAS. Lifetime is good:
600
-100
110
910
630
5.4
1800
55
27
23
600
-100
110
910
630
5.9
2700
55
22
27
600
-100
110
910
630
6.3
4000
55
17
32

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: 500V, 110mA. Use of Lundahl LL1623-120mA (3k type). This will give you appr. 20 Watt @ 28dB 2nd harmonics. (28dB distance of signal to 2nd harmonics.

 

300B-XLS Recommended Single Ended operating points
(This is just a selection, other choices are possible)
This table is for ADJUSTABLE Bias, WITHOUT Bias Resistor

Anode Voltage

(Against Heater)

Control Grid Voltage

(Against Heater)
Anode Current (mA)
Cathode Bias Resistor
Anode Rp (Ohm)

Gain
(mu)
Load
(Ohm)

Anode Dissi-pation
(Watt)

Power
Output (Watt)
2nd harm.
(dB)
400
-74
60
None
720
3.8
3500
24
11
27
400
-74
80
None
720
3.6
2500
32
13
26
Lifetime is very high:
450
-100
60
None
780
5.2
4000
27
13
26
450
-100
60
None
780
5.3
5500
27
10
31
Lifetime is very high:
450
-98
73
None
720
4.1
2000
33
16
22
450
-98
73
None
720
4.5
3000
33
13
26
450
-98
73
None
720
4.9
4500
33
11
31
Lifetime is very high:
450
-97
80
None
700
4.2
2000
36
18
22
450
-97
80
None
700
4.6
3000
36
15
26
450
-97
80
None
700
4.9
4500
36
12
31
Lifetime is high:
475
-97
90
None
670
4.7
1900
43
21
23
475
-97
90
None
670
5.1
2800
43
17
27
475
-97
90
None
670
5.5
4200
43
14
32
Lifetime is good:
500
-98
110
None
630
5.4
1800
55
27
23
500
-98
110
None
630
5.9
2700
55
22
27
500
-98
110
None
630
6.3
4000
55
17
32

The above are high power working points. Hand adjustable, no auto bias.

Design such amplifiers with care.
  • Designing a hand adjustable amplifier for users who do not know the difference between Volt and Ampere, is not always a good idea.
  • The working points of 400 and 450V need not much special attention. The tubes should be finally adjusted after burn in, and do not necessarily need monitoring. Yet lifetime is longer when the tubes are adjusted every 1000...2000 hours, or every second year.
  • The working points of 475V, and specially 500V need more attention. That is because bias depends also on the tube age, and may slowly go up during the first 1/3 of the lifetime, then stay stabile, and then go down slowly. The period where bias (may) go up is dangerous, if nobody checks it. For current monitoring, such amplifiers need a well visible, build-in meter in the amplifier. In addition, it needs an easy- to-use, fool-proof adjustment possibility.
  • Choose Auto Bias instead, if users should not be working on bias setting themselves. Auto Bias is safer, and tube life is longer. That is because the tube works always at intended working point, and human errors with power tubes is the most occurring errors cause.

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: 500V, 110mA. Use of Lundahl LL1623-120mA (3k type). This will give you appr. 20 Watt @ 28dB 2nd harmonics. (28dB distance of signal to 2nd harmonics.

 

 

EMISSION LABS 300B-XLS tube curves

EML 300B-XLS tube curves. See Note 3

 

300B-XLS Curves as white Print Version


Using curves with older Sofia Software


Circuit SImulation with SPICE


Some recommended Lundahl transformers
  Primary
 Secondary
 Anode Current
LL1623-090mA
11Hz @1.5dB 		3000Ω Alt.B = 4Ω
Alt.C = 8Ω
Alt.D = 16Ω 		90mA

LL1623-120mA
13Hz @1.5dB

 3000Ω Alt.B = 4Ω
Alt.C = 8Ω
Alt.D = 16Ω 		120mA
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.

LL1664-80mA
13Hz @1.5dB

 3000Ω 8Ω 80mA

Complete list of recommendations here

 

300B-XLS Mechanical Data

Size including Socket (but excluding pins): 175 x 63mm
Weight of one tube: 140 Gram
Shipment weight for pair in gift box: 750 Gram

Standard UX4 Base

 

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

Special Octal Base, V4 Version

 

Pin 1+2: Heater1
Pin 6+7: Heater2
Pin 8: Cathode Tap (Cathode)
Pin3: Anode
Pin5: Grid

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. Average Plate Characteristics are made with the Sofia Digital Curve tracer.
  4. 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.
  5. 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.
  6. 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.
  7. Gold Plated grids have a few advantages, such as increased bias stability, some protection against accidental overload, and better linearity of tube curves.
  8. The curves for the 300B-XLS are plotted, with DC heating.
  9. 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 ideally be 5.1V.