Schu Posted September 5, 2017 Share Posted September 5, 2017 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 Quote Link to comment Share on other sites More sharing options...
Davecv41 Posted September 5, 2017 Share Posted September 5, 2017 What circuit do you plan to use it in? Quote Link to comment Share on other sites More sharing options...
mike stehr Posted September 5, 2017 Share Posted September 5, 2017 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. Quote Link to comment Share on other sites More sharing options...
Schu Posted September 6, 2017 Author Share Posted September 6, 2017 (edited) 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 September 6, 2017 by Schu Quote Link to comment Share on other sites More sharing options...
mike stehr Posted September 6, 2017 Share Posted September 6, 2017 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. Quote Link to comment Share on other sites More sharing options...
Schu Posted September 6, 2017 Author Share Posted September 6, 2017 I have ticked all those points with Craig, including already owning Millard gz34's. Thank you for confirming what I had been reading prior to Craig getting back to me. Quote Link to comment Share on other sites More sharing options...
EMRR Posted September 6, 2017 Share Posted September 6, 2017 Are the sonics of a 274 worth the expense at this point? It's hard to imagine, but I haven't heard one apples to apples either. Quote Link to comment Share on other sites More sharing options...
Schu Posted September 6, 2017 Author Share Posted September 6, 2017 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. Quote Link to comment Share on other sites More sharing options...
Schu Posted September 17, 2017 Author Share Posted September 17, 2017 just an FYI... dont add we274b's to the VRD amplifier. Quote Link to comment Share on other sites More sharing options...
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