EML 45B

Description

2A3 Mesh tube

Features

  • The 45B tube is designed to build amplifiers with fully original '45 tube sound', but the 45B is able to do so at more than twice the output power. However the amplifier needs to be modified, or new designed.
  • Without modification, the 45B can be used in every normal 45 amplifier just as well.

High Resolution

About the 45 tube, 45B tube, and how to use it.

The 45B tube resulted from the many conversations I had with my friend Roger Modjeski, who unfortunately passed away in 2020. Roger spend his entire life and career on designing classical tube amplifiers, combining high output power with long tube life. Link to Background about the 45B project, and how to use the 45B.

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

 

EML 45B  Filament Ratings 

Filament Voltage 
= 2.5Volt (AC or DC) 
Tolerance on filament voltage
5%
Filament Current 
~ 1.5Ampere 

EML 45B Maximum Conditions

Plate Voltage 
420Volt 
Plate Current 
53mA 
Minimum Plate Dissipation
8.5Watt 
Continuous Plate Dissipation
22Watt 
Power Output in Class A 
5.2Watt 
Grid resistor

500k Ohm

EML 45B Factory Test conditions

Plate Voltage 
275V 
Plate Current
36mA 

 

45B Recommended Single Ended operating points.
Bias Method: Auto Bias.

Vb

Ua

Ug

Ia

Ra

Transformer
examples

Pa
(W)

η

Output

Damping factor

2nd harm. (dB)

Tube
         
Ω
See also note 2, 3, 4, 5
 
302V
250V
1353Ω
-46V
34mA
5k6
 
8.5
18%
1.5W
4.1
28.2

45, 45M, 45B

334V
275V
1444Ω
-56V
36mA
4k6
 
9.9
20%
2W
3.5
27
45, 45M, 45B
466V
384
2000Ω
-82V
41mA
9k2
LL1679-055 8-16Ω
15.8
20%
3.1W
4.6
29
45B only. Note7
466V
384
2000Ω
-82V
41mA
6k5
LL9202-050 4-8-16Ω
15.8
25%
4W
3.2
26.2
45B only. Note8
495V
408V
1800Ω
-87V
48mA
9k2
LL1679-055 8-16Ω
19.7
18%
3.6W
5.1
29.3
45B only. Note7
495V
408V
1800Ω
-87V
48mA
6k5
LL9202-050 4-8-16Ω
19.7
23%
4.5W
3.6
27.2
45B only. Note8
495V
408V
1800Ω
-87V
48mA
5k
LL1663-050 8Ω.
19.7
26%
5.2W
2.7
25
45B only. Note9
495V
408V
1800Ω
-87V
48mA
5k
LL1663-050 8Ω.
19.7
26%
4.5W
2.7
30.4
45B only. Note10
Credit: We want to thank Roger Modjeski, from the company RAM-LABS / Music Reference USA, for doing many detailed measurements on the 45B tube. It was shown, the published maximum distortion and maximum output power in this data sheet was achieved easily. Even so, the 45B seemed capable of doing more as published here. Thank you very much Roger!

 

45 tube curves

45 tube curves

EML 45B Mechanical Data


Ceramic UX4 Base

Size including Socket
(but excluding pins)

145 x 58 mm 

Weight of one tube:
140 Gram

Pin 1: Heater1
Pin 4: Heater2
Pin3: Anode (Plate)
Pin3: Grid

 

Notes

  • Note 1) With tubes, miniaturization and linearity do not go together well. This is explained by electrical fields having specific behavior which does not follow the miniaturization exactly. With the EML45, the plate is larger than the historical 45, which large size contributes to lower distortion. This is documented by an external company, and they report 30% lower distortion compared to historical 45. Read here.
  • Note2) Specified in idle condition. Under full signal, plate dissipation will be somewhat higher.
  • Note 3) η = Percentage of power consumed by the output tube that is converted into power at the load. For example, if a tube dissipates 12 watts of heat at idle and delivers 4 watts into the transformer, the plate efficiency would be 25%.
  • Note 4) Distortion drops considerably at lower signal. A distortion compare between two operating points should be made at the same output power.
  • Note 5) Transformer DC loss NOT included in Supply voltage. So depending on the chosen transformer, the Supply voltage needs to be chosen slightly higher, to compensate for the DC loss across the transformer.
  • Note 6) Use a scientific calculator, the formula is 20*Log R. Where R is the ratio. For R =100 you would find +40. For R=0,01 (equals 1%) you would find -40. Or use Excel instead. Enter this, and Excel will write -40 in the cell: =20*LOG(0,01)
  • Note 7) These working points give superior results for all parameters, being: Output power, distortion and damping factor.
  • Note 8) These working points provide damping factor and distortion similar to the RCA circuits. Yet at higher output power.
  • Note 9) This working point is optimized for highest output power, at the compromise of damping factor. Distortion may seem high at 5.2 Watt, but this reduces drastically at lower output signal of 4.5 Watt. For this see Note 10.
  • Note 10) This is the same working point as above, and it demonstrates an amazing 30.4dB low distortion, yet at 4.5 Watt still. However damping factor is not very high. This would be a meaningful application for loudspeaker systems using an active bass, so damping factor plays no important role.