What steel to use when making Transformers

[corduroyew]

I want to try my hand at making output transformers. Rather than just taking random types of steel and wrapping wire around it, I was wondering if anybody could tell me what some of the common steel alloys to use for transformers. I know the type of steel makes a huge difference in tone and I want to know which ones might sound good. One of Gerald Weber’s books talks about vintage transformers using the same 2 or 3 alloys but he doesn’t actually tell us which alloys they were using. Does anybody know which alloys tend to get used most often? Could it be that some of you even know how each alloy effects the tone and would be willing to share that info with me? Or am I just way to much of a nerd that should just go back to my nerdary and my nerd experiments using trial and error and in the end blowing everything up?

Any help you guys can give me would be great.

[CarlZ]

Actually you can wrap wire round a random chunk of steel. and there's probably some crafty sob that can figure out how to make it sound good too. LOL

But with regard to your question, while there are a myriad of grades of silicon steel, the big favorites that people like to wind with are M19 and M6. And if you want to get into some of the exotics, your other option is to use nickel alloy laminations. As a point of refernce I believe all the Fender trannies used plain jane M19 laminations and clearly they worked out just fine for them! M6 laminations with 413 interleaves and bandwidth spec's out to 250kHz or some other craziness like that is better left to the audiophool community. Just get your hands on some M19, paper or plastic cores, which really makes no real difference, and start experimenting and have fun with it.

-Carl

[corduroyew]

Then M19 it is. I'm not going for anthing new and exotic. I just want something that'll do the job. Thanks for the help.

[matndona]

I started out with 29M6 & feel the higher permeability you get will give you more options. Basically you'll need fewer turns to avoid saturating the core and can use a bigger primary wire for low DCR. Keeps everything cool.

This will give you more options when you start trading off turns (=Inductance = Bass response) for getting a good layering of the winds. Especially if you do any wind interleaves.

A lot of the "classic" OT's seem to use thicker, less efficient lams than HiFi 29M6 and are actually using 40VA core stacks to cover 18 or 22 Watts. You can always stack a 29M6 2x2 & pretend it's thick if you want to simulate a crappy lam! I've seen that done on at least one 18W OT clone.

I'm thinking you can worsen the performance of the good stuff, but you can't make the bad stuff good.


Matt
www.MusicalPowerSupplies.com