Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: markmalin on March 21, 2022, 05:35:46 pm
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I've been scratching my head about this...
I have a 240VAC/50hz tube preamp I need to test, and I'm in the US so my mains power is 120VAC/60hz. I purchased a 240VAC step-up transformer which I will use to run the 240V preamp for the test. The power amp I am going to plug the preamp into is going to be running off my 120VAC/60hz mains at my house. I'm probably overthinking this...I just woke up in the middle of the night thinking..."wait... there should be no issue with this, right?"
Mark
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I think you're fine, since the units are isolated from each other via your SUT. Not sure that it would've mattered anyway. However there are a lot of people who understand these things way better than me.
/Max
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> a 240VAC step-up transformer
Tell us more. Link to seller?
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> a 240VAC step-up transformer
Tell us more. Link to seller?
Here's a link to the transformer I have : https://www.amazon.com/Yinleader-Voltage-Transformer-Converter-120Volt/dp/B07PPZLX5K?th=1 (https://www.amazon.com/Yinleader-Voltage-Transformer-Converter-120Volt/dp/B07PPZLX5K?th=1)
It's the brand is "Yinleader" and the model is "F-3000P". I haven't powered this transformer up yet, I just got it a couple weeks back. I'm looking at the documentation and it looks like it can do simultaneous "110" and "220", so maybe the best route for testing is to plug both the 240V preamp and the 120V power amp into the transformer. But if possible, I'd like the power amp to run through my normal house power because I want to do some long term testing and I don't trust this unit to handle both amp sections for, say, a 2 hour soak test.
Mark
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That's dangerous, trusting the user to set the INput voltage on a hidden (backside) switch.
It's rated far more power than you can ever need. If you don't trust it, put it out on a concrete porch powered-up for a week, before the return period expires.
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... it looks like it can do simultaneous "110" and "220" ...
It cannot provide 110 and 220 outputs at the same time.
The back-side switch sets it as a step-down, and the 110v outlets are operable. Or the switch sets it as a set-up, and the 220v outlets are operable.
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Thanks guys. So back to my original question, if I run the preamp at 220V with this transformer, and plug my amp into the house mains (120v), is there any issue with running the preamp signal into the power amp input? It shouldn't care, right, because it's a signal, but I'm not sure about the grounds (earth), if that comes into play.
Again, probably a silly question, but...
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I don't see any issues other than a possible ground loop that could occur even if the preamp was operated from the same ac source.
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I don't see any issues other than a possible ground loop that could occur even if the preamp was operated from the same ac source.
Thanks