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Author Topic: Magnetostriction  (Read 48 times)

Recording Engineer

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Magnetostriction
« on: Yesterday at 06:52:32 pm »

A friend is building me a U47-type mic with a Neumann capsule. I'm currently gathering transformers from IOAudio, AMI, and Andreas Grosser as options and the IOAudio has come in first. It's the only transformer I've ever held in my hand that rattles... And apparently it's the way Neumann did it and should go away once mounted? Magnetostriction... Someone care to explain in laymen-terms and confirm this is indeed the way Neumann did it?

By the way, if anyone cares, I'm also gathering the currently-manufactured "tube substitutes/alternatives" by Telefunken, Phaedrus, IOAudio (should be available at some point this year), and my friend's wishful-thinking but completely expected to come in dead-last ("arrangement"?) with a widely-available and used cheap tube.

And we could careless that it won't sound like an original vintage U47; as we already know it won't! Just trying to make the best-sounding mic (to us) with a U47 circuit and parts-types as we can with the best readily-available parts... Andreas Grosser and some others are already do that, but this is the next-best alternative concerning price.
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klaus

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Re: Magnetostriction
« Reply #1 on: Today at 11:07:35 am »

(...) It's the only transformer I've ever held in my hand that rattles... And apparently it's the way Neumann did it and should go away once mounted? Magnetostriction...

As I understand it, magnetostriction is only present in ferromagnets- those that remain magnetized at all times (i.e. permanent magnets).
Transformer magnets, as used in condenser mics, are not ferromagnetic, so that phenomenon would not be encountered there.
I would therefore question your use of the word "apparently".

Besides, I have never run into rattling magnets in microphones, new ones or old ones, aside those with badly constructed or sloppily assembled transformers. Which would indicate that, whatever rattles in yours will not go away with time.

I would suggest you inspect the transformer closely for manufacturing slop.
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Klaus Heyne
German Masterworks
www.GermanMasterworks.com
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