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Discussion Starter #1
So I received (from Netherlands) the JMP1C I’ve been chasing for a while. And it has an interesting unexpected “problem” — power input is labelled as 230V/50Hz and the power chord supplied is the round prong version.

It didn’t occur to me that anything that has been recently manufactured would not utilize a universal power supply, but I guess it makes some sense in this case.

I will find a decent 110-to-230V power transformer, but does anyone else have any insight or thoughts on this issue?
 

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Most electronics meant for american distribution will differ from their euro counterparts.

If the stepdown doesnt bug you, it is your best bet. If it does, time to find one originally sold on this continent.
 

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A good step down transformer (can handle the current of the amp) = $50. A new PT so you don't have to carry that step down around with you = $100. New PT is better but costs more.
 

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Discussion Starter #4
A good step down transformer (can handle the current of the amp) = $50. A new PT so you don't have to carry that step down around with you = $100. New PT is better but costs more.
I thinks it is technically a step up transformer: 110V mains out to 230V amp power in. Any suggestions for what a “good one” is and where to find one such good one?

I don’t think I want to modify the amp. While they do sound fantastic, they are a bit of a collector thing which means I probably shouldn’t screw with it.
 

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Does the converter change the cycle rate as well? We use 220 @ 60Hz they use 230 @50hz
 

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Discussion Starter #8
Does the converter change the cycle rate as well? We use 220 @ 60Hz they use 230 @50hz
I am sure cycle-changing power converters exist, but that’s a far more sophisticated (ie expensive) circuit than just a straight transformer.

There are 3 functions on the secondary side of the power transformer in the amp: a) full-bridge rectification from AC into DC, b) direct AC tube heaters supply, and c) power light. None of these functions should be affected adversely by the cycle rate. In fact, 60Hz likely results in cleaner DC than 50Hz in the same rectification circuit.

There are designs where 50Hz vs 60Hz would matter, but I don’t think a modern solid-state, full bridge-rectified design with sufficient filtering for 50Hz already in place would be one of those.
 

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As far as the frequency question, stuff built for 50Hz will run a bit cooler on 60Hz, but the opposite can sometimes be a problem. So stuff built for 60Hz can sometimes have overheating issues running on 50Hz.
So like Dan said, should not be an issue in this case.
 

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Discussion Starter #12
Step up transformers are surprisingly difficult to find in a brick and mortar store around here (step down is easier). Picked one up today from Sayal (a semi-legit and meta-serious electronics store chain) and the stupid thing is defective and blowing fuses even with nothing plugged in. And the frustrating part is that it was clearly sold as defective since when I started looking for spare fuses in its box, I found a stash of already-blown fuses there! And the shop is now closed until Mon, so no euro-powered amp for me this weekend :-(.
 

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You can get a transformer, works fine, plugs into your standard wall outlet. I have 2 and they work well. I'd sell one if you want it.
 

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Discussion Starter #17
Update: after sorting through several sealed yet non-working ones, we found a step-up transformer unit at the store that seemed to actually power up and also not immediately blow its fuses. Sheesh.

But the end result is ... a really amazing-sounding euro-powered JMP1C! I am not sure if it’s the aftermarket tubes, the extra juice of the 230V power supply variant of the circuit, or the extended anticipation, but this one sounds extra sweet with excellent range in the tone controls. It is definitely a keeper.

This is the step-up transformer I now have:



And while it seems to now be working, it’s overkill (amp only needs 25W) and will be a pain to lug around, so I am also now waiting until the following one becomes available again, if ever:



Thanks for all the help and support!
 
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