• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

2A3 power supply transformer

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I am making a simple 2A3 amp and it is my very first tube amp. In making it, I bought a good price tube power transformer from asia with the spec of primary @110V and secondary @ 380VAC. Because the US is running at @120V, therefore, the new secondary output became 418V, instead of 380V for 2A3's design.

Since I am new in tube, can I use the 2A3 working under 418VAC (before rectifier 5U4GB)? Should I need to modify anything to accomondate the higher voltage?

Thanks,

Thomas
 
should be fine

The difference in transformer secondary voltage between this one and the one you describe is not very significant. If you are trying to get everything perfect, then maybe you should be concerned but in reality you could change a few values and arrive at the correct voltages with no trouble. It is a lot easier to reduce voltage than make it up...sorta like making something shorter is much easier than making it longer!

Please realize that all voltages will change slightly using this transformer vs the one called for.

Besides that, the voltage supplied to your house is not exactly 120v all the time and everyplace.

Yes, you will need to check calculated voltages to determine if you have any problems but I'll bet you are probably ok.

Can you analyze circuits, voltages, drops, etc?
 
Download a copy of PSUD and start tweaking some values to get it in the range you want. It's free and easy to use. Choke input (LC) would be about right for a 418Vac secondary and as arnoldc has said, you can add a small (<3uF) cap before the first L to tweak the final voltage. PSUD will show you what's going on for this small cap, but I've never found it accurate enough to design and apply directly to the circuit. Start low and build up in increments until it's correct.
 
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