Not just an replacement, but an improvement!

EML 320B-XLS
Equivalent to 842

Uploaded: 27-Jun-2017 17:32


Guarantee

The first owner can register the tube at the Emission Labs website, to participate in the 5 years guarantee program.

Description
The XLS Series tubes are based on an extra large size (XLS)  plate system.  This system is taken from earlier EML 52B tubes, and has proven to be ideal for high power applications. 

The EML 320B-XLS  is a version of the 300B-XLS with higher peak emission.  In cases where this extra emission is not required, the 300B-XLS is the better choice. The higher peak emission of the 320B-XLS results from the higher heater current of this tube. Specially for Push Pull amplifiers, 320B-XLS is "the" choice. However it needs to be checked if the amplifier can supply the higher heater current needed. Another application is for Single Ended amplifiers that have their performance limits in the standard 300B tubes used, and not in the amplifier hardware itself. Such amplifiers can often already be recognized by the higher weight, such as the VAIC, Mastersound, and several others. These have a large power supply, well sized output transformers, and ideally the option to set the plate current of the output tube.

A final application is for such amplifiers that seem to have low tube life with any 300B, regardless what brand 300B is used. Such amplifiers stress the tubes by default. The higher heater current of the 320B-XLS makes this tube more resistant against anything, and more lifetime as with standard 300B may be expected.

The EML 320B-XLS will bias  like a normal 300B tube,  when used in any 300B amplifier. When used like this, due to the stronger electron emission, this tube  will develop the output signal with  more ease.  When biased higher than a standard 300B,   the EML 320B-XLS will show more of  it's superior quality. It will show a better dynamic behavior, and lower distortion at all power levels. 

Heater Current Special Note:

The higher emission results from the higher heater current of this tube. It needs to be checked if the amplifier can supply the higher heater current, and still guarantee the heater voltage of 5Volt. Under heating of the 320B-XLS is definitely not allowed. It should be 5.0 Volt, with a tolerance of 5%. In case you have too low heater voltage by mistake, the tube initially performs well, however bias problems will occur after a few hundred hours. If you are not sure if the higher heater current can be supplied, you should check the heater voltage with a voltmeter. You need 5V with 5% tolerance. For the rest there are no restrictions, and this tube can replace any 300B or 300B-XLS directly.

All critical parts, like heaters, grids and plates are constructed of hard metal for higher reliability and reproducible quality. 

PUSH-PULL special note:

Push pull with (any) DHT is much harder for the tubes than SE. You may easily see low quality 300B fail in PP amplifiers. The higher heater current of the 320B-XLS allows higher plate current peaks, and this makes the tube so well suited for Push-Pull amplifiers.

Features

  • Gold plated, Wolfram Grid
  • Soft rubber suspended tube base
  • Center tapped heater
  • Slow Start heaters, for best lifetime
  • Double Mica tube top
  • Hard metal Construction (Note1)
  • Two extra large getters
  • Hand blown Glass bulb
  • Anti-microphonic plate- 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 plated pins,  black ceramic socket.  (White bottom.)


EML 320B-XLS
Equivalent to 842

Curves - (Note3)

.
EML 320B-XLS heater Ratings
heater Voltage 
= 5 Volt (AC or DC) 
Tolerance on heater voltage
5%
heater Current

~ 1.7 Ampere

.
EML 320B-XLS Maximum Conditions 
(Voltage and current not possible simultaneously - not a recommended operating point)
Plate Voltage 
550Volt 
Plate Current 
160mA 
Power Output in Class A 
22Watt 
Peak Plate Dissipation
65 Watt, one minute.
(See Note5)

Highest possible Grid to ground resistor, Single Ended.

150kOhm 

Highest possible Grid to ground resistor, Push-Pull.

50kOhm 
.
320B-XLS Recommended Single Ended operating points
(This is just a selection, other choices are possible)

Plate Voltage

(Against Heater)

Grid Voltage

(Against Heater)

Plate Current (ma)
Plate Rp (Ohm)
Load
(Ohm)

Plate Dissi-pation

(Watt)

Power
Output (Watt)
2nd harm.
(dB)
.
450
-97
80
700
2000
36
18
22
450
-97
80
700
3000
36
15
26
450
-97
80
700
4500
36
12
31
.
475
-97
90
670
1900
43
21
23
475
-97
90
670
2800
43
17
27
475
-97
90
670
4200
43
14
32
.
500
-98
110
630
1800
55
27
23
500
-98
110
630
2700
55
22
27
500
-98
110
630
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.


Curves of 300B-XLS apply

.

EML 320B-XLS Mechanical Data
Size including Socket
(but excluding pins)

175 x 63mm 
6.9 x 2.5 Inch

Single Tube weight 
170 Gram 
Shipment weight for 
pair in gift box 
870 Gram
.
  • Note 1)  Hard-metal filaments prevent filament breakage with DHT Tubes.  This material has a higher melting point than the classical nickel wires. Hard metal plates have a more precise plate distance, and do not change shape when heated.  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.   This ensures better uniformity and linearity at the low end of the tube curves.
  • Note 2)  Individual Test data, such as:  Matching Data, Grid Current, Vacuum, Filament Current, etc.,  are on the Certificate that comes with each individual Tube.  Each tube  is numbered, inside the bulb  with a metal Tag
  • Note 3)  Maximum specifications. These data are only to show the safety distance to the recommended operating point.   You can operate the tube at the maximum for a short period of time.  Exceeding the maximum, will decrease the lifetime  very rapidly.  For absolute maximum lifetime, choose the working point from the the "typical"  dissipation  (green table) 
  • Note 4)  Plate Curves:  Check the plate curves of this tube, and note that at higher dissipation, the curves get more linear.  The result of this is very positive for the sound of the tube.    First, more linearity means, the not good sounding  3rd. + 5th. harmonic will reduce.   Second,  the  tube plate resistance will be lower at higher dissipation.  (Plate resistance is measured as the angle of the curves).  A lower Plate resistance  will give a better damping factor of the bass speaker.  The result of this is a more exact transformation of the electrical signal into the correct speaker movements, giving a more natural sound, also at  low power level. 
  • Note 5)  Continuous absolute maximum plate dissipation we do not specify for this tube, as this is no recommended operating point anyway. Instead, we have a table with recommended, safe working points for low power, medium power and high power. Also we specify the peak plate dissipation for this tube here, which is a value that may occur by accidental overdrive, or other situations which take less than one minute, and do not continuously repeat.

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