pole piece material? - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 24th February 2004, 11:45 AM   #1
tuneman is offline tuneman  Australia
diyAudio Member
 
Join Date: Feb 2004
Location: pitts of hell!!
Default pole piece material?

im am curious to know what steel is required to make pole pieces top/back plates etc? i've always assumed it is a very hight carbon steel is this correct?

also if one were to make a pole piece out of solid copper what would happen? taking into account eddie currents etc
  Reply With Quote
Old 25th February 2004, 08:40 PM   #2
sreten is online now sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
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.
  Reply With Quote
Old 25th February 2004, 09:10 PM   #3
diyAudio Member
 
Timn8ter's Avatar
 
Join Date: Jul 2003
Location: Seattle, WA
Steel or iron. Strontium ferrite perhaps?
  Reply With Quote
Old 25th February 2004, 09:22 PM   #4
sreten is online now sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
AFAIK except for high performance units pole pieces are made
of soft iron, pure enough or with enough additives to prevent
it rusting.

Copper plating is one way of adding Faraday rings.

sreten.
  Reply With Quote
Old 25th February 2004, 09:51 PM   #5
markp is offline markp  United States
diyAudio Member
 
Join Date: Oct 2003
Location: L.A., CA
Most stainless steel is non-magnetic or a very poor magnet.
__________________
If it sounds good... it is good!
  Reply With Quote
Old 25th February 2004, 10:40 PM   #6
Mark Kravchenko
diyAudio Member
 
mwmkravchenko's Avatar
 
Join Date: Jan 2002
Location: Perth Canada
Default Iron is best

The lower the carbon content the better. Stainless is a poor choice as it is a poor magnetic conductor. Generally 1010 steel is used in production drivers. Normal mild steel is 1018 and suffers a bit in the total possible flux level it can support.

Mark
__________________
Mark
www.kravchenko-audio.com
  Reply With Quote
Old 25th February 2004, 10:42 PM   #7
diyAudio Member
 
Join Date: Aug 2002
Location: Seattle or Shanghai
Exactly. Low carbon content; 1006 if you can get it, 1008, 1010, or 12L14 are acceptable grades as well.

Dan Wiggins
Adire Audio
  Reply With Quote
Old 25th February 2004, 11:49 PM   #8
diyAudio Member
 
Join Date: Jan 2004
Location: Toronto, ON, Canada
I think they have a 1005 grade as well.

I suppose if one had enough money on hand, they could build pole pieces out of Permendur (iron/cobalt), which, IIRC, handles the highest flux density of all alloys.
  Reply With Quote
Old 26th February 2004, 05:49 AM   #9
Wizard of Kelts
diyAudio Moderator
 
Join Date: Sep 2001
Location: Connecticut, The Nutmeg State
Here is some info from a very interesting fellow on pole pieces and loudspeaker magnetics in general:
http://home5.inet.tele.dk/f-hammer/f...l/fildcoil.htm


Here is the link to the general site. Well woth having a look around:
http://home5.inet.tele.dk/f-hammer/
__________________
"A friend will help you move. A really good friend will help you move a body."
-Anonymous
  Reply With Quote
Old 26th February 2004, 06:27 AM   #10
jcarr is offline jcarr  United States
diyAudio Member
 
Join Date: Jul 2002
Location: Tokyo, Japan
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
__________________
http://www.lyraconnoisseur.com/, http://www.lyraaudio.com
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
WHY???? Midrange magnet's vented pole piece sealed by design - Thiel CS3.5 ???? dtm1962 Multi-Way 1 24th July 2008 05:28 PM
WTB: CS8412-CP - 1 piece reaction Swap Meet 1 12th October 2006 11:53 AM
XXLS - No Pole Piece Vent mike.e Subwoofers 7 7th January 2005 10:49 AM
Pole Piece Q ALFIrE Multi-Way 3 24th December 2004 07:09 PM


New To Site? Need Help?

All times are GMT. The time now is 01:46 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2