Best Sounding Magnet!

[Paradise_Ice]

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?

[454Casull]

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.

[BillFitzmaurice]

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.

[jcarr]

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

[johnnyx]

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.

[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 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.

[Paradise_Ice]

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 don’t?
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)

[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)

[454Casull]

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.

[Bull]

Yeh some magnets make a speaker sound 'vintage' such as alnico magnets.