Sourcing Soft Alloy Trafo Laminations

[vinyvamos]

I have been researching the DIY audio trafo route for a while now, and now having built my own winding machine I am really itching to get hold of some lams and get snapping some hair-thin wire.

First point; I am on the edge of Europe in Iceland, so sourcing from mainland Europe is my goal. M6 lams can be got in small quantities from ascocomponents.co.uk but at a price that does not warrant me winding my own power trafos at least. Maybe custom audio output iron. But still, Carnhill can supply me with a few standard ratios for good prices. And then it comes to sourcing the more fancy core materials...

MuMetal, Orthonol, and Permendur are the ones I am curious for. After emailing twelve suppliers across Europe and Asia I only managed to get a quote from one German supplier called Marchandise, and their MOQ is 20kg at €225 per kg for MuMetal (80% Nickel). This amounts to a sh#tload of money to spend on something that might be a total failure for me. ha! They are probably getting it from China. None of the Chinese manufacturers replied to my requests, so of course their MOQ will be even higher...

I read on one thread here that Magnetic Metals (USA) do not make EI and similar laminations any longer. If I am wrong then please correct me. Sourcing from the States is not out of the question but shipping would somewhat hit my budget.

Then comes Permendur/Supermendur, which is something I really want to try in a few small trafos. I have a suspicion that RCA used it in their mic trafos, maybe someone knows more about that?? This suspicion comes from me dissecting one 900849 trafo and upon seeing shiny lams I do a DMG spot test, and it's negative. The lams are harder than expected when scored with a scriber. Could this be the cobalt and a dash of Vanadium? Maaaaaybe....

Any input that anyone can give would be much appreciated by this slightly frustrated and ice-cold winding nerd in the far North...

 

[Whoops]

Hello,
I get my supplies from this dealer in Portugal:

http://www.duarteneves.com/en/178-material-fabrico-transformadores


You have to ask for the minimum quantity they sell, since they are supplying industries  and not small workshops like ourselves, but they have a pretty good selection and good quality

 

[vinyvamos]

Ah thank you for that! I have emailed them now. It seems that they only have silicon steel lams, and I am looking for nickel-based ones, but I am also interested in winding some silicon iron output trafos. We will see!

 

[CJ]

since the Golden Age of Audio is long gone, you will be stuck with whatever alloy you can find,

usually this will be 80 Ni

South Korea is currently leading the nickel lamination world.

there are a few EI lams available from Korea online at evilbay in small quantities.

Mag Met use to send samples if you worked for a large company, but that is now gone.

Mr. Finke at Mag Met knew every alloy under the sun, and all the heat treats too, but he retired about 5 years ago so lam knowledge is being loaded into dumpsters as we speak.

 

[murrayatuptown]

Maybe somebody has an opinion here.

I found a box of puny lamination samples and bobbins...but the bobbins got put in a different box by some arbitrary decision. I found the laminations again. They are EI-094 and FF-094, (not to be confused with EI-94) which I think have a 0.103" wide center leg (the E's). Cosmo shows bobbins for EI-094 & that's where I got the 'core width' dimension from. A square bobbin has flanges around 0.27" x 0.27", so they are awfully small.

What's cool (even if useless) is there are two types of material...one that sounds like silicon steel and the other being Supermendur.

Are they even too small for mic transformers? I've never seen an assembled transformer that small.

Hmm...maybe tiny gapped chokes for preamp tube level plate current...

Thanks

 

[vinyvamos]

There are incredibly small mic input transformers that exist, such as Beyerdynamic in a tiny metal can. Considering the small levels coming from most mics, this is where the minimum size and extension of LF frequency response is dictated really. As for your two lam materials, I have seen manufacturers do a mixture of both in a core. Half steel, half hi-perm, as they were probably not managing to handle the levels with 100% hi-perm core. Easiest thing to swap out is lams until they got a happy inductance to level handling ratio.

 

[Fdieck56]

If you‘are experimenting why not put out want to buy bad transformer ads for certain types. I would think as many vintage transformers must out there there be some shorted winding, open coil, dented cover ect. transformers out there.