Hey guys! I’m proud to say that I am the new owner of, what I believe to be, a ‘95 blueface vh4S as the serial # is 006. The only problem is that it is hard-wired to 230v. After speaking to Peter and a few other people, I am under the impression that there is not a 120v tap from the main transformer. My only option would be a step down/up transformer! Do any of you have any experience using one of these? Any advice and/or recommendations would be greatly appreciated as I do not want to destroy this amazing amp and piece of Diezel history! Thanks in advance!
I haven't used one with a Diezel, but I have used one with a Hughes and Kettner Tubemeister Deluxe 20. I bought it in Japan for somewhere around the equivalent of $30 to $50. You need to make sure the power rating is high enough to handle the amp's maximum possible power/current draw--usually that is printed somewhere near the power cord/plug, but you can probably ask Peter for more info on it. For perspective, the H&K 20 watt amp is rated at 101 watts, so roughly 1A of current at 100V in Japan, or a bit less at 120V in the USA.
Beyond that, because you're dealing with a very expensive piece of gear, I wouldn't skimp and just jump for whatever is cheapest. Many of the voltage converters/transformers available are intended for travel, and only for basic everyday goods, and the quality can vary greatly. Mine was made in China, but the brand is Japanese and the headquarters was right down the road from me when I bought it. My only beef with it is the voltage switch (for going from 120V to 100V or vice versa) was a bit unclear if your Japanese isn't native level--but I emailed them and they cleared it up, and then I labeled it myself for future reference. Otherwise it's a very basic device with maybe a 1 meter cord and only a single outlet, which is fine when you're intending to use it for an amp. Haven't noticed any issues like noise.
That said, a product made for only one-way (step down 230v to 120v) instead of two-way (step up/down) voltage conversion might save you some money and may be easier to find. Just make sure the plugs at each end are what you need--you don't want to have to throw in a plug converter as well, as that just adds more possibilities for something to go wrong.