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we274b/5ar4


Schu

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does anyone know if a western electric 274b can be used in a circuit that is designed for a 5ar4? what technical component is important to check?

 

we274b

Heater

  • Uf………………5V
  • If…………… 2.5A

Maximum Rating

  • anode inverse peak voltage……………1550V
  • anode peak current        ………750mA

Recommend working condition

  • Anode supply voltage             2×500V
  • Each arm impedance               75Ω
  • load impedance                   2000Ω
  • Filter capacitor                 4μF
  • Rectifier current                ≧220mA

 

 

from what I read, it's more closely related to a 5au4g... but that circuit can use a 5ar4

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The 274B is a directly heated rectifier, with just a coated filament. (the filament is the cathode) The 5AR4 has a cathode...being it's an indirectly heated rectifier. That means the 274B is a "instant on" type of rectifier, whereas the 5AR4/GZ34 guessing takes 11 seconds to warm up the cathode.

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The heating of the equation is what was explained to me as being a potential issue also. Doesn't mean it can't be used, but it can additionally stress a system

 

I am wondering if the sonic improvement of a western electric 274b would be worth the chance of stress related failure.

Edited by Schu
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You need to make sure that inrush of voltage/current from using a directly heated rectifier doesn't exceed the voltage/current rating of the input PS capacitor or other power supply caps.

You may be fine. Then again over time, that slam of inrush voltage/current could stress the PS caps that much quicker.

 

Buy a pair of Mullard GZ34s and call it a day. If the amplifiers in question are VRDs, why not ask Craig? He'll give you the best answer.

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I have heard sonic changes in rectifier replacement... I do not think anyone could tell you one way or another without trying it first.

I am already running copper lined Millard gz34's which may not be comparable to some of the vintage metal base gz34's, but they are no slouch.

The western electric tubes I have heard personally have something special... the Chinese replications are worth the stretch financially imho if there is even a hint of the original sound.

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