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Thread: LE5-2 AlNiCo vs LE5-5 Ferrite

  1. #1
    magnet
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    LE5-2 AlNiCo vs LE5-5 Ferrite

    Ferrite magnets are ceramics made primarily from iron and boron with a small amount of strontium. By weight they are stronger than steel or Alnico equivalents but less so than neodymium magnets. Like all ceramics, they are quite brittle & will easily break if dropped onto a hard surface. They are the most economical for their strength.

    Can anyone comment on the truth as to why JBL dropped the AlNiCo magnet and went into production with the ferrite magnets?

    Cost or greater magnet strength w/less distoration?

    JBL Marketing seemed to focus on the later...

    What was the JBL Development / Engineering scoop?
    Last edited by magnet; 04-07-2004 at 09:30 PM.

  2. #2
    leif
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    If they say it was for less distortion, then I guess they have a problem to justify why they use Alnico magnet in the bass driver for the new K2 s9800

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    Administrator Mr. Widget's Avatar
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    Re: LE5-2 AlNiCo vs LE5-5 Ferrite

    Originally posted by magnet


    Can anyone comment on the truth as to why JBL dropped the AlNiCo magnet and went into production with the ferrite magnets?
    This has been discussed at length on previous threads. The reason JBL retooled their entire line was due to a civil war in Zaire where most of the world's cobalt comes from.

    Here is a post Don made on the subject.

    _________________

    Here's the skinny on the Alnico crisis of 1978. The geographic center of this situation was the Kolwezi mining region of Zaire. At the time, Zaire accounted for over 60% of the world’s production of cobalt. In 1977, rebels calling themselves the Front for the National Liberation of the Congo, invaded from Angola. In May 1978, the cobalt mines in Kolwezi were taken by the rebels and flooded. Zaire’s cobalt production was effectively shut down. Considering that most of the remaining cobalt producers were either behind the iron curtain, or tied up by the defence industry due to the strategic value of the metal, the net result was that cobalt was pretty much eliminated from the commercial market.

    Regarding JBL (and I assume the other speaker manufacturers), they were told by their magnet suppliers that Alnico magnets would not be available once the current stock was depleted. Greg Timbers (who was at JBL at the time) stated it wasn’t a matter of cost. Their magnet suppliers could not provide any new quantity of Alnico magnets. There was enough stock to continue production for a limited time, but a rush program was developed to convert the bass drivers to ferrite magnets since they represented the largest consumption of magnets. In less than a year, the SFG magnet topology was developed and put into production.

    By 1979, France, Belgium and the USA had interceded in the civil war and the cobalt mines were back in production – albeit at reduced output. Alnico magnets became available again at higher cost. JBL continued the manufacture of Alnico compression drivers until 1981, when it was decided that the economies of switching to ferrite could no longer be ignored.

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    Don McRitchie

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    Senior Member Guido's Avatar
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    Originally posted by leif
    If they say it was for less distortion, then I guess they have a problem to justify why they use Alnico magnet in the bass driver for the new K2 s9800
    Yes the distortion of Alnico Drivers is higher. Some call it the "Alnico Sound"
    I think the higher distortion is not caused by the alnico itself but the design of the older magnet/basket structure.
    I'm damned shure that this is improved in the AL 1500

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    Originally posted by leif
    If they say it was for less distortion, then I guess they have a problem to justify why they use Alnico magnet in the bass driver for the new K2 s9800
    The ALNICO assembly in the 1500AL is not your dad's ALNICO assembly on his D130! JBL went to great lengths to improve the new ALNICO assembly above and beyond the SFG ferrites. Not only does it have significantly reduced distortion content, it also doesn't have the demag problems of the original ALNICO assemblies.

    As for the ferrite versus the alnico LE5. When JBL first bolted that ferrite magnet onto the back of the LE5 frame they were astounded at the reduction in distortion. I have long since lost that paper on the LE5 discussion about the differences but I remember reduction in distortion was not the goal, it was a very pleasant side effect.

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    Senior Señor boputnam's Avatar
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    Originally posted by Giskard
    ...When JBL first bolted that ferrite magnet onto the back of the LE5 frame they were astounded at the reduction in distortion.
    Uh-oh... There goes the secondary market for them LE5-2's - yet again. There is usually a fresh crop of them that appear on eBay whenever they get proper "recognition", here. Surely there will be some collateral damage to the market for the mystical L100's, too...
    bo

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    Registered User MJC's Avatar
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    Originally posted by Giskard
    The ALNICO assembly in the 1500AL is not your dad's ALNICO assembly on his D130! JBL went to great lengths to improve the new ALNICO assembly above and beyond the SFG ferrites. Not only does it have significantly reduced distortion content, it also doesn't have the demag problems of the original ALNICO assemblies.
    Why is the '77 112As such a good speaker? Maybe the best mid-bass driver ever. Was Zaire the reason that JBL never used the 112A in any other speaker after the L212?

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    Originally posted by boputnam
    Uh-oh... There goes the secondary market for them LE5-2's - yet again. There is usually a fresh crop of them that appear on eBay whenever they get proper "recognition", here. Surely there will be some collateral damage to the market for the mystical L100's, too...
    Well, that means people aren't using the two holes in the sides of their heads then. I'm thinking one either likes the sound or one doesn't.
    Originally posted by MJC
    Was Zaire the reason that JBL never used the 112A in any other speaker after the L212?
    I doubt it. The 2108 is the 112A in Pro clothes and it was used in the 4315. It's simply a purpose-built driver that scaled nicely with the other components it was involved with. JBL kept it around long enough to build ferrite versions of both the 112 (112H) and the 2108 (2108H). The 4315 used the 8" midbass, the 4343 used the 10" midbass, and the 4350 used the 12" midbass.

    ***

    It's really no different than the 121A or 121H in the B212. Purpose-built for the task at hand and only used in the B212 to my knowledge. 108H in the L250 and 250Ti (same as a 2118H but with aquaplas sprayed on the back of the cone), etc. JBL does stuff like that
    Last edited by 4313B; 04-08-2004 at 07:41 AM.

  9. #9
    Senior Señor boputnam's Avatar
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    Originally posted by Giskard
    Well, that means people aren't using the two holes in the sides of their heads then.
    So that's what they are for. :shock: Wow, I gotta go...
    bo

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    Well, isn't it true? If you like the way something sounds you're not going to give a rat's ass whether someone else posts "theory" or "measurements" or "facts" or any other crap right? Aren't you just going to go and enjoy what you enjoy?

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    Administrator Mr. Widget's Avatar
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    Originally posted by Giskard


    Well, isn't it true? If you like the way something sounds you're not going to give a rat's ass whether someone else posts "theory" or "measurements" or "facts" or any other crap right? Aren't you just going to go and enjoy what you enjoy?
    Damn it Giskard, now you are letting all the secrets out.

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    Yeah, we're kicking out all the stops on this one!

    Fortunately it'll all get buried in the pile of rubble that makes up this forum

  13. #13
    Senior Señor boputnam's Avatar
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    Originally posted by Giskard
    Fortunately it'll all get buried in the pile of rubble that makes up this forum
    Damn it Giskard, now you are letting all the secrets out.

    bo

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