Best Sounding Magnet! - 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 12th June 2004, 04:55 PM   #1
diyAudio Member
 
Paradise_Ice's Avatar
 
Join Date: Jun 2004
Location: cosmological consciousness
Default Best Sounding Magnet!

People argue that, magnets sound different?
Is this just the force factor of each magnet there talking about or does each type of magnet have a different sound quality?
Lets say we have 2 woofers and everything is equal,
We have one with a Samarium-Cobalt magnet and one with a
strontium-ferrite, lets also say each one has the same field strength, do you think there is a sound quality difference?
  Reply With Quote
Old 12th June 2004, 08:38 PM   #2
diyAudio Member
 
Join Date: Jan 2004
Location: Toronto, ON, Canada
This is just like the cables argument... I would say no, if the magnetic field acting on the voice coil is exactly the same, then there is no audible or measurable difference, aside from total mass of the driver.
  Reply With Quote
Old 12th June 2004, 09:09 PM   #3
Banned
 
Join Date: May 2004
Location: New Hampshire
I second that motion. The magnet merely supplies the driving force for the system. A gauss is a gauss irrespective of the source material. There can be some differences at very high power levels where the magnet's heat sinking abilities can affect the power compression factor, but that's seldom a concern for non-pro usage.
  Reply With Quote
Old 12th June 2004, 10:17 PM   #4
jcarr is offline jcarr  United States
diyAudio Member
 
Join Date: Jul 2002
Location: Tokyo, Japan
Ideally speaking, a magnet would not have a sound of its own. Here in the real world, it has been my experience that equal-strength magnets of different composition may indeed sound different when used in transducers. Ditto for the polepiece material.

OTOH, I don't think that it is possible to perfectly match different magnets for strict comparison purposes, because the B-H curves will be different (even when comparing magnets all within the rare-earth family - SmCo, Presedymium, Neodymium).

hth, jonathan carr
__________________
http://www.lyraconnoisseur.com/, http://www.lyraaudio.com
  Reply With Quote
Old 12th June 2004, 10:57 PM   #5
johnnyx is offline johnnyx  United Kingdom
diyAudio Member
 
Join Date: Jan 2004
Location: manchester
I read an article in Electronics World by John Watkinson about loudspeaker magnets, as part of a series on loudspeakers. He replied to a letter criticising his comments on magnetic materials, saying;- "ceramic magnets are good.. for picking up swarfe when I'm machining the pole peices for my neodymium magnets".

He argues that ceramic is an insulator, while neodymium is a conductor, and so it prevents - if I remember the spelling - Barkhaussen noise. It's the movement of the magnetic domains apparently, and is also found in tape heads.
  Reply With Quote
Old 13th June 2004, 12:18 AM   #6
diyAudio Member
 
LineSource's Avatar
 
Join Date: Sep 2003
Location: SiliconValley
Default NdFeB or Field Coil

The current in the voice coil generates a magnetic field that can "appear" to reduce the pole piece magnetic field and create distortion. Ceramic magnets are more susceptible to this reverse field modulation than NdFeB or Alnico. And this BL modulation distortion is much greater in high power woofers than low wattage tweeters/mids. Electric Field coils are theoretically the lowest distortion magnets, but are very large, expensive, and require a well regulated high current power supply. NdFeB is the best permanent magnet material. NdFeB has a 5x to 10x higher magnetic field than ferrite or Alnico magnets, and hence can create high fields, or dramatically reduce weight. Since iron saturates at 1.7 Tesla, this stronger magnet can best be used to create a dual field motor, or a long underhung motor.

For woofers and high excursion mids where a long voice coil is attractive for power dissipation, the JBL Differential drive is very attractive as it lowers coil inductance without requiring a field reducing Faraday ring. This uses NdFeB's strength to create dual fields.

For high detail mids and tweeters where a short coil is attractive for low mass, an underhung radial motor and heavy copper Faraday ring is very attractive. Seas has the Hexadym NdFeB motor to approximate a radial motor, and Aura uses several thin cylinder segments to create a radial magnet since NdFeB cannot be cast to precise tolerances and is too brittle to machine.
  Reply With Quote
Old 13th June 2004, 04:25 PM   #7
diyAudio Member
 
Paradise_Ice's Avatar
 
Join Date: Jun 2004
Location: cosmological consciousness
Default Re: NdFeB or Field Coil

Quote:
Originally posted by LineSource
The current in the voice coil generates a magnetic field that can "appear" to reduce the pole piece magnetic field and create distortion. Ceramic magnets are more susceptible to this reverse field modulation than NdFeB or Alnico. And this BL modulation distortion is much greater in high power woofers than low wattage
For high detail mids and tweeters where a short coil is attractive for low mass, an underhung radial motor and heavy copper Faraday ring is very attractive. Seas has the Hexadym NdFeB motor to approximate a radial motor, and Aura uses several thin cylinder segments to create a radial magnet since NdFeB cannot be cast to precise tolerances and is too brittle to machine.
The distortion ripples can be seen on a TV screen, this gives a visual trace of the reverse field modulation, the magnet and coil in battle, my friend swear by NdFeB for tweeters but I think they can sound rather harsh which is subjective, but in woofers I feel they offer a lower distortion at large linear travel, some manufacturers use a combination of magnets which I think is a gimmick or do they know something I donít?
ATC claim to have Super Linear magnet system, I personally agree with most of the work.
Here is a link to the to download an attachment of there theory.
Super Linear Technical White Paper (.zip)
I still believe that magnets have some way to go!




Super Linear Technical White Paper (.zip)
  Reply With Quote
Old 13th June 2004, 04:27 PM   #8
diyAudio Member
 
Paradise_Ice's Avatar
 
Join Date: Jun 2004
Location: cosmological consciousness
Sorry you will have to go to the end link on the main menu,

Technology, its the 4 one down.

Super Linear Technical White Paper (.zip)
  Reply With Quote
Old 13th June 2004, 08:18 PM   #9
diyAudio Member
 
Join Date: Jan 2004
Location: Toronto, ON, Canada
Quote:
Originally posted by Paradise_Ice
Sorry you will have to go to the end link on the main menu,

Technology, its the 4 one down.

Super Linear Technical White Paper (.zip)
I'm thinking this is probably some sort of permalloy... i.e. a Ni-Fe alloy. Acts just like a temporary magnet, except is an insulator.
  Reply With Quote
Old 13th June 2004, 09:02 PM   #10
Bull is offline Bull  United Kingdom
diyAudio Member
 
Join Date: Oct 2002
Location: ...........
Default reply

Yeh some magnets make a speaker sound 'vintage' such as alnico magnets.
  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
Best sounding DIY SS amp trespasser_guy Solid State 73 24th April 2014 05:09 AM
What is better sounding I/V con. ? Gasho Digital Source 25 29th September 2010 07:21 PM
magnet design 101 - saturate iron with a ferrite magnet? capslock Multi-Way 18 28th April 2010 05:51 AM
Box-tuning magnet-to-magnet construction Mr_Oasis Full Range 21 2nd June 2009 01:51 AM


New To Site? Need Help?

All times are GMT. The time now is 11:43 PM.


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