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RE: " Maybe I should be looking for a toroidal transformer"

I will only agree with what John Curl says if it is amended along these lines:

curl: What we forgot was that the windings of a toroid transformer are wound on top of each other, rather than in separate bobbins.

to make it factual: What we forgot was that the windings of a toroid transformer are typically wound on top of each other, rather than in separate bobbins.

I guess my point is that the problem curl mentions is not a function of the toroid but a function of how nearly all of them are wound. There is absolutely no reason why someone cannot wind a toroid with the primary as a semicircle on one half of the core and the secondary on the other half effectively giving the results of a dual bobbin device and I really have a problem with people lumping design choices choices and factual data into the same pile. It is not the fault of the toroid that it is wide bandwidth, it is the fault of the designer of the transformer. Next thing you know we will all be accepting the universal fact that tubes have a mushy vintage sound.

While I am at it, there is another gross overgeneralization used in magnetics wrt C-cores vs. EI cores and that is the following often repeated fact about the superiority of C-cores

The grain direction stays parallel to the winding length for the entire magnetic circuit for C-cores and stamped laminations always have some portion of the magnetic path that runs perpendicular to the grain.

The problem here is what happens when you are using a non-oriented material? As many of you know, I love nickel as a core material and it just so happens that the materials I use are all non-oriented and lets just say that being lectured by customers on the "universal superiority" of c-cores gets tiresome. To close things out I will give the one universal benefit of the tape wound cores is the ability to use much thinner lamination thickness than with stamped lams and the one benefit of stamped lams over C-cores is the possibility of a much smaller airgap.

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