R Core Transformers


2007-07-06 7:38 am
you greet to everybody
for which to recommend the transformer r-core application?
me to look for a transformer to only feed current anodic of my preamplifier to tubes.
what transformer to be the best for feeding... toroid... r-core... c-core....
thanks for the suggestion
I talked to John Galaway, Western Regional Sales Manager for CUI Inc., this afternoon. Nice guy. He told me that CUI Inc. has all their transformers manufactured offshore in China and that his company is exiting the R Core transformer business due to soft demand. He further said that even if they were not exiting the line, buying a couple of transformers from him would not be cost effective due to the high freight charge on small orders from China to Oregon. Looks like CUI Inc. is not an option for us, so if anyone has any other ideas please let us know. Thanks. James
I will give Electro Assemblies a call tomorrow. I have the feeling after talking to CUI Inc and looking at a number of other websites that most of the R Core transformers are manufactured by a very small number of contract suppliers in Asia. Not only do many of the transformers have a very similar look, but the data sheets all seem strangely familiar. I would be interested in buying direct from an Asian distributor if the total cost including shipping was reasonable. James
I recently emailed at least 6 different U.S. manufacturers of R core transformers that I found via Google. None bothered to reply, not even the manufacturers that boasted prototyping and "one offs." This experience taught me that there is no U.S. manufacturer of R core transformers willing to sell to the hobbyist.

Aside from the few that are sporadically available on Ebay, there are only 2 sources that I know of:

The place in Hong Kong/ China

The French supplier (100 euro minimum)

Good luck. I gave up on finding an R core transformer in the U.S.
I called Electro Assemblies this morning and talked to Jeff Swanson, National Sales Manager. Another nice guy who took time out of his busy day to answer my questions. Electro Assemblies, like CUI Inc, does not manufacture R Cores in house, but buys them from China and resells them in the US. Jeff told me that there are very few companies that are able to manufacture R Cores: two in China, two in India, two in the US, and one in Japan. The US manufactures are Custom Magnetics, North Manchester, IN and Lenco Electronics, Mchenry, IL. I will call both of these companies as soon as I get a chance. Jeff also told me that Electro Assemblies is exiting the R Core business due to soft demand. Jeff believes that the only application where an R Core is superior to a good toroidal and thus worth the extra cost is audio and as Jeff pointed out there just aren't enough US audio manufactures doing large enough volume to make a R Core business. Lastly, I did find another company that sells a limited selection of R Cores online. The web site is:http://www.icl.co.jp/audio/english/index.htm.
jimmyd53 said:
Kitamura Kiden sells retail through a subsidiary named Phoenix. Their web site is www.pnxcorp.co.jp. The web site is in Japanese so maybe one of our Japanese fluent members can investigate and report back. Please and Thank You. James


Out of my own interest, I contacted this manufacturer in Japan. The response was quick. Their RA series is intended for individuals and everything is order-made so getting a transformer designed for USA 115V is not a problem at all. Alas, they don't ship to abroad... If there are enough interest (and enough number of people willing to pay the extra shipping), I may consolidate an order...



Paid Member
2002-03-29 5:19 am
I have looked at a number of vendors mentioned in this thread as well as eBay. As someone mentioned, almost all appear to be made in China no matter where you purchase them. I have not been able to determine whether any of these transormers are built to appropriate safety standards, i.e., UL, CSA, or any of the various European "alphabet soup" of regulatory agencies. Given the horror stories about the lack of quality and quality control in Chinese manufacturing, I'm extremely concerned about the very real possibility of one of these transformers burning my house down after some amount of time. Even the apparently reputable Selectronic company in France gives no indication of agency approval for these transformers.
Millions of R-core transformers made in factories in Asia – mostly in China- are in use in various equipments worldwide. UL, CSA and EU quality certifying agencies have offices in China, Taiwan, India and many other countries of Asia. Many big manufacturers of transformers in this region have approval of these agencies and importers in USA, Canada, EU import from them.