You can't make a pole piece out of copper as its non-magnetic.
High carbon steel is required for extreme hardness, a factor
I can't see any relevance to the application. Stainless steel,
obviously, the only other relevant parameter I'd guess is
maximum flux density before saturation.
sreten.
High carbon steel is required for extreme hardness, a factor
I can't see any relevance to the application. Stainless steel,
obviously, the only other relevant parameter I'd guess is
maximum flux density before saturation.
sreten.
Here is some info from a very interesting fellow on pole pieces and loudspeaker magnetics in general:
http://home5.inet.tele.dk/f-hammer/fildcoil/fildcoil.htm
Here is the link to the general site. Well woth having a look around:
http://home5.inet.tele.dk/f-hammer/
http://home5.inet.tele.dk/f-hammer/fildcoil/fildcoil.htm
Here is the link to the general site. Well woth having a look around:
http://home5.inet.tele.dk/f-hammer/
For MC cartridges I've designed and use polepieces made of Permendur as well as soft iron and chemically purified iron (which is about 4~5 times the cost of permendur). For a variety of reasons, I like chemically purified iron the best. Subjectively I like how it sounds better than Permendur, and if you are willing to invest in electro-chemical machining, you can make some pretty precise and intricate polepieces shapes. If you choose Permendur, you will most likely be limited to fairly basic polepiece shapes.
Mind you, the comparatively small size of the magnets used in MC cartridges means that the polepieces are not being pushed to anywhere near saturation limits, even when using something like Neodymium 50.
regards, jonathan carr
Mind you, the comparatively small size of the magnets used in MC cartridges means that the polepieces are not being pushed to anywhere near saturation limits, even when using something like Neodymium 50.
regards, jonathan carr
thanks for that so where do you aquire those types of steels? especially in a australia, any australians here know?
and what exactly are faraday rings? i've see copper rings used on the motors on compression drivers and some 6 inch mids once is this what your talking about?
and what exactly are faraday rings? i've see copper rings used on the motors on compression drivers and some 6 inch mids once is this what your talking about?
Faraday rings? Shorting rings? They can be made of aluminum or copper. Don't forget extended pole pieces.
This interesting link explains all.
http://ldsg.snippets.org/motors.php3
This interesting link explains all.
http://ldsg.snippets.org/motors.php3
Industrial Metal Supply in California and on the net has every metal in every variety(almost). Also try McMaster/Carr on the net for all your needs.SmarmyDog said:Hep Me! Hep Me!
New guy here. I'm working on a subwoofer driver design & prototype (first one - getting my feet wet). Does anyone know of a source for some 1/4-inch thick 1006 plate (or 1008 or 1010 [thanks DanW]) . I'll need eight 16" by 16" squares.
Thanks, Casey Walsh
Doesnt the pole piece need to be magnetic?
I was taught that the reason the cores for transformers were made from soft iron is that it doesnt retain a magnetic field when one is applied to it. So your traffo isnt going to turn into one huge permenant magnet after a while of use.
Obviously the AC put thru it would tend to magnetise it one way then the other, if thats possible. Maybe its just soft iron is easily demagnetised but is also easily magnatised too, so if nothing is going to kill the magnetic field it will remain strong.
Either way id like to know. Was my physics teacher wrong? I cant imagine he was because he was very good and was very intelligent.
I was taught that the reason the cores for transformers were made from soft iron is that it doesnt retain a magnetic field when one is applied to it. So your traffo isnt going to turn into one huge permenant magnet after a while of use.
Obviously the AC put thru it would tend to magnetise it one way then the other, if thats possible. Maybe its just soft iron is easily demagnetised but is also easily magnatised too, so if nothing is going to kill the magnetic field it will remain strong.
Either way id like to know. Was my physics teacher wrong? I cant imagine he was because he was very good and was very intelligent.
In my quest for some 16” x 16”, ¼” thick plates of a high-permeability metal, do I need to be concerned with Electrical Resistivity, Saturation Flux Density, Coercivity, Residual Induction, or Hysteresis Loss?
BTW, another source of metal is http://www.scientificalloys.net.
-Casey Walsh
BTW, another source of metal is http://www.scientificalloys.net.
-Casey Walsh
Pole piece / Back plate material
We are a menufacturer for loudspeaker pole piece, so I can tall you that we used low carbon steel (SEA-1006 & SEA-1008) to produce pole piece.
http://www.million.url.tw
We are a menufacturer for loudspeaker pole piece, so I can tall you that we used low carbon steel (SEA-1006 & SEA-1008) to produce pole piece.
http://www.million.url.tw
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