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lamination material for transformers and chokes

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maxdimario:
Apart from the wire and winding techniques, lamination or core material has a marked influence on the sonic end-result of transformers and chokes.

I was wondering what sonic characteristics different metals have, not considering the various winding methods.

nickel? iron? mu-metal? what are the metals available today for transformers and what is their sonic signature?

dcollins:
maxdimario wrote on Mon, 11 December 2006 20:32
Apart from the wire and winding techniques, lamination or core material has a marked influence on the sonic end-result of transformers and chokes.

I was wondering what sonic characteristics different metals have, not considering the various winding methods.

nickel? iron? mu-metal? what are the metals available today for transformers and what is their sonic signature?




Oh, yes.

Absolutely.

DC

maxdimario:
hmm..
does that mean I can make my own transformers with any old laminations and they will do just as well?

It's relatively easy to copy windings.

Oliver Archut:
Hello Max,

what about the sound of a transformer?

The sound of a transformer is mostly in the metal. Why? That is a kind of difficult question.
Here is one good example, what we refer to as Mu-Metal today was original developed by the Magnetic Shield corporation and is a loose world for anything that has to do with audio transformers, magnetic shields, etc.
Even Mu-Metal is today a registered trademark, there are several manufactures that offer a generic version of it.
The original Mu-Metal composition is

C 0.015
Mn 0.50
P 0.005 max
S 0.001 max
Si 0.30
Cr 0.02 max
Ni 80.20
Mo 4.85
Al 0.01 max
Co 0.02 max
Fe Balance

but most of the so called generic version and alternatives have slightly different trace elements that make the technical specs nearly the same but the overall audible sound is sometimes very different.
In my trials over the years in dealing with audio transformers the smoothness or harshness is given by the type of raw metal that is used for the lamination/transformer.

All additional high mu metal that are available today are based on the 80Ni/15Fe the rest even chromium, molybdenum or cobalt.
What the best alloy is, that is open for debate because the shape of the lamination is the 2nd most important part, where sometimes two types of the same lamination but from two different manufacture (cut different) can sound like day and night.

Best example is the early V72 units made by Maihak, they used Krupp lamination vs. the standard Siemens ones. There is a distinct difference in the upper mid range....

The situation about transformer cores is pretty dark today because there is hardly any manufacture left that offers audio grade "Nickel". Here in the US there is Magnetic Metal and BMI left that still offer off the shelf lamination, but from the 200 or so classic x-former lamination 90% of all are special order and sometimes not available at all.

It is pretty much like the electron tube, a specialty market product....

Best regards,

maxdimario:
So the metal in the laminations makes a big difference.

the smoothness in the top end is a result of lamination material.

I imagine it's difficult to measure?

I remember that the v76s has a different core material for the HPF inductor to reduce distortion in the lows as well.. right? I think you mentioned nickle there.

can slew-rate and overshoot be altered by the core material?

why is the nickle today not up to audio standards as you say? is it a question of purity?

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