Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: 12AX7 on January 23, 2013, 04:52:35 pm
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I had a tube recto when i first built this marshall type amp. But i can't recall the voltages. Right now i have 440 on the el34 plates with a SS recto and 100/100uf main cap can that i would swap to a 32/32uf along with the tube rectifier if i do this. from 440v on the plates, what do you think it will drop to with a 5AR4? Also, can i just swap in various rectos (yes, i know i'd have to rebias) and if so what kind of drop with a 5U4GB or a GZ34, assuming i can use either. PT is a hammond, but i can't recall the model.
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Yes
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I know it WILL drop, i was just asking if anyone knew by how much.
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Extremely useful chart put together by Tubenit and I think Geezer? Anyway, it's all there. :smiley:
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I know it WILL drop, i was just asking if anyone knew by how much.
Very vague info. You have the amp. Why don't you just do it then tell us the results. Should be safe.
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And while the chart reflects actual observations, actual resulting B+ is a complex interaction between PT voltage output, PT current ratings, rectifier tube voltage drop (usually seen as a set amount of resistance, so more drop for more current), filter cap size and load current drawn by the amp.
RDH4 doesn't give any kind of equations, but a series of ways to evaluate the different variables above, then have you make reference to a series of charts that summarize the hard math for you. It's an involved process to predict the actual resulting B+ from a power supply.
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Thanks.