Ok, before we are turning year this is my last new thread in this forum for 2009...
where can I buy R cores and bobbins (or with another words: coil formers)?
I have been chasing and sending emails almost around the whole globe but don't have good luck, most even don't care to reply.. 🙁
Seems like the only choice is to buy a ready made power transformer from SELECTRONIC : Composants Electroniques, Systèmes d’Alarme, Matériel Electronique
in France and strip of all the windings.
C cores could do if there are no R cores.
Cheers Michael
where can I buy R cores and bobbins (or with another words: coil formers)?
I have been chasing and sending emails almost around the whole globe but don't have good luck, most even don't care to reply.. 🙁
Seems like the only choice is to buy a ready made power transformer from SELECTRONIC : Composants Electroniques, Systèmes d’Alarme, Matériel Electronique
in France and strip of all the windings.
C cores could do if there are no R cores.
Cheers Michael
A happy new year.
R-Core was invented by Kitamura Kiden Co., Ltd. in Japan.
They also developed R-Core dedicated winding machine.
Their Web is located as follows:
KITAMURA KIDEN CO.,LTD.
They have European sales office in Swiss.
If this is a mains transformer your best bet may still be buying a complete transformer and stripping/rewinding the secondaries. Not sure how realistic is to wind primaries at home.
ja2dhc,
Thank you, I wish you too Happy New Year!
I am aware Kitamura Kiden invented the R core if I understood it correct and have sent e-mail to them in Japan, but I wasn't aware of an European office, good, I will check with them in Switzerland.
Cheers Michael
Thank you, I wish you too Happy New Year!
I am aware Kitamura Kiden invented the R core if I understood it correct and have sent e-mail to them in Japan, but I wasn't aware of an European office, good, I will check with them in Switzerland.
Cheers Michael
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The only thing that worries me is the quality of the steel and the thickness of the laminates if it was designed for a power transformer...?
Cheers Michael
So, these are output transformers? How do you intend to wind them? There seem to be some pretty cheap R-core outputs available from Japan.
Raw C cores in a variety of sizes were readily available on eBay the last time I checked. Most are from Chinese vendors, but appear to be made with exotic Japanese transformer steel alloys. (The ones I considered) These were intended for use in winding OPTs. This was late last year to early this year so I don't know what the current situation is.
I am not sure why you would want to wind an opt on an R-core, imho (and in very limited testing) they seem to have relatively limited primary inductance and significant leakage inductance due to the bobbin design.
I am not sure why you would want to wind an opt on an R-core, imho (and in very limited testing) they seem to have relatively limited primary inductance and significant leakage inductance due to the bobbin design.
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analog_sa,
yes, sorry I should have stated clearly earlier: I am looking for the raw material for an OPT.
They are a bit tricky to wind which I am fully aware of and I know besides the very expensive brands from Japan at least one that offers "budget" OPTs which is Softone.
Did you know any other affordable maker in Japan using R-core?
Cheers Michael
yes, sorry I should have stated clearly earlier: I am looking for the raw material for an OPT.
They are a bit tricky to wind which I am fully aware of and I know besides the very expensive brands from Japan at least one that offers "budget" OPTs which is Softone.
Did you know any other affordable maker in Japan using R-core?
Cheers Michael
Hi Kevin,
that's true, the R-cores seem to be popular mainly in Asia, I have been in touch with vt4c as they have R-core power transformer that can be winded per customers order, so I sent them an e-mail whether they could make an OPT but the iron used was of "bad quality" according to them and wanted me to buy their E-I core OPTs instead.
Audio Catalog
Why R-cores, I guess they look mystic to me! 😛
Cheers Michael
that's true, the R-cores seem to be popular mainly in Asia, I have been in touch with vt4c as they have R-core power transformer that can be winded per customers order, so I sent them an e-mail whether they could make an OPT but the iron used was of "bad quality" according to them and wanted me to buy their E-I core OPTs instead.
Audio Catalog
Why R-cores, I guess they look mystic to me! 😛
Cheers Michael
I am only aware of Softone and their transformers seem fair, although apparently deficient in the bass, possibly for the reason Kevin mentioned.
Btw i use several of VT4C R-core power transformers and find them excellent.
Btw i use several of VT4C R-core power transformers and find them excellent.
I don't know much about Softone more than their homepage which is a bit modest, or have they been around for a long time, haven't seen many posts regarding their OPTs.
I just noticed they had one OPT on the Triode Festival shoot-out earlier this autumn but there was some mix-up between theirs and some others OPT according to one Japanese member here on DIYaudio so I am not sure which one is which, also I think all the OPTs were only SE in the shoot-out, not so much to go on.
SE OPTs for that matter do have much lower inductance than OPTs meant for PP as they have to have an air-gap, hmm.. where did you get that information Softones OPTs have a weak bass performance?
BTW could mention the cores are going into a KT88 PP UL which I have started lightly to plan, I wrote a bit in TubeMacks KT88 thread.
Cheers Michael
I just noticed they had one OPT on the Triode Festival shoot-out earlier this autumn but there was some mix-up between theirs and some others OPT according to one Japanese member here on DIYaudio so I am not sure which one is which, also I think all the OPTs were only SE in the shoot-out, not so much to go on.
SE OPTs for that matter do have much lower inductance than OPTs meant for PP as they have to have an air-gap, hmm.. where did you get that information Softones OPTs have a weak bass performance?
BTW could mention the cores are going into a KT88 PP UL which I have started lightly to plan, I wrote a bit in TubeMacks KT88 thread.
Cheers Michael
Softone's RW-20 was proceeded to the BEST 4 at the ETF 2009's shootout.
Please refer to the below thread (especially later posts describe about Softone)
http://www.diyaudio.com/forums/tubes-valves/155809-greetings-etf.html
Regarding to the winding method for the R-Core, it needs dedicated
winding machine and bobbin. Please consult with the SWISS office of Kitamura.
Hi ja2dhc,
thank you for your reply!
I have searched the internet extensively for Kitamura Kiden's office in Switzerland but unfortunately I have not found it, could you perhaps help me I would be very thankful for your help
I have contacted by e-mail both Kitamutra Kiden and pnxcorp.co.jp on December 21st and they have not answered since then.
Cheers Michael
Hi,
Not sure if you mean the core kit type cores available from a few appearing and disapearing vendors in China?.
I purchased a set that was supposed to be able to do 100W per pair. Hmm, not too sure about that. I tested them at 50HZ as two sets of cores ie. double c-core and managed 300VA before rather violent saturation. Not much good at <20Hz for one set of cores then.
They say they are Z11 which is merely the same as M6 type material. Also the quality was on the medium to low side. One pair of cores was lovely, interestingly they have a sticker on them which indicates how many turns of the strip the operator managed before running out of space. The other pair is rough. It has broken strip in a couple of places and the sticker indicates much less material was used. The rest is just glue. So with this core there are a few airgaps/gluegaps in series. The faces of the cores are very good and look to have been finished on a surface grinder.
So overall I would say dont buy them. The price after shipping etc. is slightly more than some top notch cores from a more local supplier.
As for R-Cores I wonder if it is a good choice for an OPT. Maybe in push pull with CCS to balance the currents. They look more trouble than torroids apart from the easier winding.
Cheers
Matt
I have called to HQ of Kitamura in Japan. They said that SWISS
office was cloased and HQ is directly handling European customers, now.
Please send an E-Mail to info@kitamura-kiden.co.jp which they check for
E-mails everyday.
Z11 is a product name of Nippon Steel Corporation which is the biggest
manufacturer for Electro Magnetic Steel Products in the world.
Nippon Steel Corporation
Catalogs of Electrical sheets can be downloaded from the below URLs.
http://www.nsc.co.jp/en/product/sheet/pdf/DE307.pdf
http://www.nsc.co.jp/en/product/sheet/pdf/DE304.pdf
I have Softone's RW-40 which uses 160VA rated R-Core.
"160VA" means AC50Hz Power Transformer usage. I suspect
Softone degrades 160VA/50Hz rated core to fit 40W rated SE OPT
since the half frequency needs 4 times rating.
ie: 160VA/50Hz=40VA/25Hz
Hi ja2dhc - Softone on the their website mention that they use 50 watt core for RW-40 (PP) and RW-20(SE). It is mentioned in chart. How is that your
transformer has 160VA core ?
You have typo-mis.
[WRONG] RW-40 (PP)
[CORRECT] RX-40 (PP)
RW-40 is for SE. RX-40 for PP
You are wright. According to their Web, each model vs R-core rating
is as follows:
RW-20(SE): 50VA rated core
RX-40(PP): 50VA rated core
RX-80(PP): 160VA rated core
RW-40(SE):160VA rated core
Mine is RW-40 therefore 160VA is used.
ja2dhc,
Thank you for your help, very kind of you calling them to check the status on Swiss office.
The e-mail address you gave me is the exact address I have used, I sent an e-mail already on 21st of December and another e-mail yesterday but so far not heard of anything from them.
I am aware of the RX-80 from softone which could be suitable for my upcoming KT88 PP amplifier, but first I would like to try on my own make the output transformers, I see it simply as part of the DIY joy and pleasure.
ja2dhc, what is your impression of the softone transformer in your amplifier?
Cheers Michael
I gave them a caution to be careful to check foreign mails. I am afraid that
you are using HTML mail which is easily rejected by their anti-spam system
as automatically determined as SPAM.
My RW-40 is used for an E-Linear amplifier which was developed by
Pete Millett.
My amp is seen at the below URL (sorry, written in Japanese).
http://ja1cty.servehttp.com192.168.1.2/E-LINEAR/E-LINEAR2.html
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