I need a 100v to 220v step up trans.I'm in Japan (100v) attempting to power 2 neumann N52t psu's (220v) which hopefully will power an SM23c.I'm guessing this is a custom job btu finding the right people in Tokyo is a bit daunting.Can anyone recommend a tech or company abroad?Anyone else had a similar situation,and how did you solve it?

I would guess that whatever the Japanese equivalent of Farnell/Mouser is will stock something appropriate. No one I know in Japan has ever had a serious problem running European equipment. Any 100-110/220-230 converter with an appropriate power rating should be fine.

tarandfeathers wrote:No one I know in Japan has ever had a serious problem running European equipment. Any 100-110/220-230 converter with an appropriate power rating should be fine.

This is certainly true for most gear.But some valve stuff is finicky and mores to the point,according to Klaus Heyne ,there are no fully regulated PSU's for valve mics(modern and vintage),including the vintage supplies I intend to use.The performance of the mic is directly related to the voltages the valves see.In my case I could undersupply the AC701 valves with a 110-220v convertor,but get increased noise.Better than cooking them but not the best solution.My alternative is to play swap the resistor in the PSU itself to compensate.I'm not sure if this is advisable, and would need undoing if I move.And my soldering skills don't encompass more than connectors at the moment.

When was the last time you measured exactly what was coming out of your wall sockets? I'll bet you it isn't exactly 100V. There's likely to be up to 10% variance either way so unless you invest in some sort of UPS system that you're going to carry around with you you'll have to change those resistors every time you use the mics in a different building if you want every voltage to be exactly perfect. Realistically, equipment is designed to work with small changes in mains supply. The way it works might alter slightly (less or more headroom, less or more noise), but so long as you don't stray too far from the intended supply (230V is, for example only an increase of 4.5% from 220V) it should be fine.

Additionally, if you're going to spring for a custom transformer, I'd get a new mains transformer with dual primaries done for the power supplies themselves so you can easily switch them and not have to worry about carting a bulky, irritating box with you.

I'm pretty sure that Peace Music in Tokyo has a valve Neumann or two, You could call them and check what they do but I think it's just a regular, off the shelf converter.

Excellent point concerning AC fluctuations.Something I'd forgotten!Hopefully I can keep that as the last variable.I'll do a bit more local hunting,including calling Peace,and report back.Thanks for the considered responses.

Any other ideas appreciated.