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-   -   Why non magnetic resistors? (http://www.diyaudio.com/forums/parts/224803-why-non-magnetic-resistors.html)

jeepy 2nd December 2012 08:31 AM

Why non magnetic resistors?
 
I would appreciate feedback on this. Do magnetic resistors really affect the sound even if not located close to a transformer?

tinitus 2nd December 2012 08:35 AM

needs iron to be magnetic

there is another thread on this subject
but I dont remember where it is

marce 2nd December 2012 09:47 AM

If they have AC signals going through them they wont be magnetised for long, but as stated there is a long thread on residual magnetism in some passive commponents.
Any components located near a transformer are going to be affercted by the magnetic fields as will any leads PCB's etc so its best to keep stuff away from transformers full stop.
As to magnetic components in otherparts of the system, music is AC, and AC demagnetises, you could magnetise things if you played DC though:)
Most things are magnetic to some degree or other, iron based magnetism is ferromagnetism, if I remember correctly this early in a morning.

DF96 2nd December 2012 03:44 PM

Some components have plated steel leads, presumably because it is cheaper than copper. Some people say this affects the sound. My guess is that it does not, except perhaps in some critical positions. It is not something I worry about.

jcx 2nd December 2012 04:06 PM

steel core copper clad wire is simply stronger - makes it easier to handle the lead wire in the part's production where the forces would deform pure copper

likewise many resistors are ceramic rods which have to have endcaps press fit - some use brass/bronze formulations but steel is again cheaper, can have better elastic properties to give more secure press fit

as a designer of sensor signal conditioning, industrial instrumentation with decades experience - some at large companies with dozens of other similarly experienced engineers I never heard that this use of steel core wire/endcaps had bad consequences - no one checked for them in design reviews - depending on transducer our measurements were sometimes thermal noise limited

they do have to be avoided in MRI or other sensitive mag field measurements

magnoman 2nd December 2012 04:41 PM

We were careful to screen against any magnetic materials in mass spectrometers electronics where trajectories could be effected. Though I personally never saw any performance difference between these units and initial development units built with standard commercial parts where some nickel and other materials were used.

Thanks
-Antonio

marce 3rd December 2012 11:27 AM

Most commercial stuff and medical is SMD these days so the problem of lead material isn't as relevant as it was. These days PTH components are only going to be found in lower end commercial stuff, and where they can afford the labour intensive costs of PTH.


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