Hi guys
I'm not sure about magnetic parts... like screws, washers, standoffs etc.
are they to be avoided in the circumference of components 'n circuits (like, fasten rectifiers, Mos-/J-fets etc., or even PCBs)?
many thanks!
I'm not sure about magnetic parts... like screws, washers, standoffs etc.
are they to be avoided in the circumference of components 'n circuits (like, fasten rectifiers, Mos-/J-fets etc., or even PCBs)?
many thanks!
The magnetic field produced by a magnetised screw would be very weak indeed and highly unlikely to affect nearby electrical components.
If you're really concerned, just heat the offending screw beyond its Curie temperature when it will lose its magnetism. For iron and steel, this is 770 degrees C.
Standard torch burners can give temperatures up to 800 degrees C. Please note that I am being scientifically correct and I really don't think the procedure is necessary! 🙂
Standard torch burners can give temperatures up to 800 degrees C. Please note that I am being scientifically correct and I really don't think the procedure is necessary! 🙂
I'll trust your knowledge, and leave them as magnetic as they may be (but eventually just avoid them on the very critical places)...
…beyond its curry temperature...
(will look up Curie right afterwards, thought that was "Marie", who died an awful death due to her research?)
In general, they pose no problem unless you have to design something that will need to operate in ultra-high field areas, like a MRI room, or closer for you the giant magnets of the CERN.
There are exceptions though, some examples: the vicinity of magnetic sensors, be they Hall, eddy currents or else (they are used in position sensors, current probes, etc).
The vicinity of coils having an open or semi-open magnetic circuit is another one: if you place a magnetic screw near the main filter coil of a class D amplifier, it risks becoming red-hot if it is of an open type variety.
Even if the heating is moderate, the operating characteristics will be affected.
Also, never use a magnetic screw (or even a conducting one) to fasten a Xover coil or a magnetic circuit: it would be tempting to use the center hole of potcores (or Xcores, or similar) to fasten them, but resist the temptation, even if they operate at a low power level.
There are certainly many other examples, but it is impossible to be exhaustive: you need to use your own common sense (and the forum collective knowledge) to decide whether it is problematic or not
I see there's a distinction to be made here - between a magnetic screw and a magnetised screw.
I was considering the effects of a magnetised fixing screw on nearby components, but Elvee eruditely describes the effect of a component's (filter coil's) magnetic field on the fixing screw.
The plot thickens! 😎
I was considering the effects of a magnetised fixing screw on nearby components, but Elvee eruditely describes the effect of a component's (filter coil's) magnetic field on the fixing screw.
The plot thickens! 😎
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Hi All.
I was hoping to explore this a little further.
Some sources advise the avoidance of Ferris material in the signal path.
Examples would be, speaker cable, cable terminals, loudspeaker enclosure wiring, binding posts, banana plugs, and anything associated with these such as nuts, screws etc.
What was advised was that the charge associated with the current flowing through ferrous material tends to have a lag before discharging in comparison to non ferrous materials through which there is no lag. This lag is due to the magnetic properties of ferrous.
The theory is that this charge build up can distort the analogue waves being carried and result in smudged sound reproduction.
Avoiding ferrous in the signal path is said to provide a clean signal path.
What are your thoughts?
I was hoping to explore this a little further.
Some sources advise the avoidance of Ferris material in the signal path.
Examples would be, speaker cable, cable terminals, loudspeaker enclosure wiring, binding posts, banana plugs, and anything associated with these such as nuts, screws etc.
What was advised was that the charge associated with the current flowing through ferrous material tends to have a lag before discharging in comparison to non ferrous materials through which there is no lag. This lag is due to the magnetic properties of ferrous.
The theory is that this charge build up can distort the analogue waves being carried and result in smudged sound reproduction.
Avoiding ferrous in the signal path is said to provide a clean signal path.
What are your thoughts?
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The definition of a ferrous material is a material in which the base metal is iron. I'm not aware of any speaker cables or enlosure wiring which employ ferrous materials.
Iron is a ferromagnetic metal. The other ferromagnetic metals are nickel and cobalt. Magnetically 'soft' materials such as annealed iron can become magnetic in strong magnetic fields, but lose their magnetism when the field is removed.
The base metal of the majority of speaker binding posts and banana plugs is brass which is an alloy of copper and zinc, neither of which metals is ferromagnetic.
The brass can be plated with tin (non magnetic), gold (non-magnetic) or nickel (magnetic, but the coating is so thin as to be negligible in its magnetic effect).
So, you see, ferrous materials are largely avoided in the signal path anyway.
Some perfectionists insist on copper connectors instead of the more common binding posts and banana plugs, but I very much doubt that I would hear a difference! 😉
As soon as a conductor is ferromagnetic (meaning µr>1, not necessarily containing iron, or even a magnetic element [some ferromagnetic alloys do not contain any ferromagnetic element]), its skin depth is hugely reduced at high frequencies increasing its AC resistance.
This can cause alterations in the frequency response (realistically, not over the length of a binding post though), and non-linear distortions because of the hysteresis (saturation is also a theoretical possibility, but not a practical one considering the current density of a real conductor).
Cables are normally made of copper or aluminum (non-magnetic), but I have seen cables from Chinese origin attracted by a magnet, thus beware of cheap deals
This can cause alterations in the frequency response (realistically, not over the length of a binding post though), and non-linear distortions because of the hysteresis (saturation is also a theoretical possibility, but not a practical one considering the current density of a real conductor).
Cables are normally made of copper or aluminum (non-magnetic), but I have seen cables from Chinese origin attracted by a magnet, thus beware of cheap deals
Did you mean ferrous element? Some rare earth elements also have ferromagnetic properties. Gadolinium, samarium, neodymium are all examples of magnetic rare earth metals.
However, to avoid confusing the issue, these elements are used, in combination with iron, cobalt and nickel, in the manufacture of magnets - and not in the manufacture of binding posts and banana plugs. 🙂
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What has me intrigued a bit is that there are coax-cables with a steel-core, which are said to be very suitable for audio-applications...
But this brings topic down to a dull level, sorry.
But this brings topic down to a dull level, sorry.
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Thanks All.
I've been dabbling in vintage loudspeaker refurbishment.
After testing with a magnet, I've found a significant percentage of them contain ferrous or magnetic binding posts, and other parts.
I'm also finding many manufacturers are supplying banana plugs and binding posts which are attracted to a magnets.
Even a pair of original Danish Dali Loudspeakers which included crossovers built with quality air core inductors and poly caps had steel nuts fitted to the binding posts.
These days I'm careful to avoid anything ferrous in the signal path.
I guess the real question is, to what extent does this contribute to interference with sound reproduction??
I've been dabbling in vintage loudspeaker refurbishment.
After testing with a magnet, I've found a significant percentage of them contain ferrous or magnetic binding posts, and other parts.
I'm also finding many manufacturers are supplying banana plugs and binding posts which are attracted to a magnets.
Even a pair of original Danish Dali Loudspeakers which included crossovers built with quality air core inductors and poly caps had steel nuts fitted to the binding posts.
These days I'm careful to avoid anything ferrous in the signal path.
I guess the real question is, to what extent does this contribute to interference with sound reproduction??
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Paramagnetic material is irrelevant to to sound reproduction. Take your magnet and test the wires of regular resistors: most of them are magnetic. Hold your magnet against SMD parts - what do you find?
Elelectric components contain paramagnetic wires for decades😛
Elelectric components contain paramagnetic wires for decades😛
Can you give examples of the manufacturers, suppliers or particular items to which you are referring?
Note, however, that nickel plated components may be attracted to a magnet.
I gave away the ferrous examples.
As I wasn't mindful of ferrous issues at the time I didn't think to identify parts by supplier and just placed them loose in a box.
I found the ones branded "Nakamichi" [copy], were OK (no ferrous).
I'll definitely identify suppliers of ferrous parts in future.
As I wasn't mindful of ferrous issues at the time I didn't think to identify parts by supplier and just placed them loose in a box.
I found the ones branded "Nakamichi" [copy], were OK (no ferrous).
I'll definitely identify suppliers of ferrous parts in future.
Cliff, do you think it may be worth making a distinction, considering your earlier question about the operation of capacitors if they might become magnetised.. between the operation of components in the proximity of a fixed magnetic field, and the effect of operating components in the vicinity of ferrous material?
Yes, even less relevant than ferromagnetic material in the context of the currents flowing in loudspeaker cables and connectors.
Ferromagnetic materials can become permanently magnetised, but paramagnetic materials can only, in most cases, be temporarily magnetised.
Some metals are so weakly paramagnetic that an ordinary magnet does not attract them, an example being aluminium.