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Thread: Recharging Alnico/Ferrite magnets

  1. #31
    Senior Member edgewound's Avatar
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    Wow, Greg...Thanks for the education.

    It is extremely generous of you to take the time to post here with "from the Designer's Desk" info.

    It's very much appreciated.
    Edgewound...JBL Pro Authorized...since 1988
    Upland Loudspeaker Service, Upland, CA

  2. #32
    Administrator Mr. Widget's Avatar
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    Very interesting....



    Widget

  3. #33
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    so- cool!!

    Holy crap!

    GT- you have a unique way of saying it all. We BS each other for months on end to no real avail on certain subjects. You make a single post and "POOF"- issue is swept under the rug and we now work with facts- not opinions. If you only knew how beneficial it is to us....all I can say is "THANK YOU, SIR !!!". However, don't let this cut into making more kick-butt speakers!

    Travis.

    moderator: Can we put a copy of Greg's post here ??

  4. #34
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    Quote Originally Posted by hapy._.face
    GT- you have a unique way of saying it all. We BS each other for months on end to no real avail on certain subjects. You make a single post and "POOF"- issue is swept under the rug and we now work with facts- not opinions.
    You nailed it dude! A little of his time can clear up a whole lot of other time...

    I suspect we are starting to see where that "Moderation Frustration" was coming from with respect to the endless threads, arguments, speculations, etc...

    Question? Answer. Slam dunk! He scores!!! Game over man! Game over...
    Quote Originally Posted by hapy._.face
    moderator: Can we put a copy of Greg's post here ??
    Techbot must be online right now. Looks like it's been handled already.

  5. #35
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    Quote Originally Posted by gtimbers
    Most of the qualifying 4" motors will loose 1 - 1.5 dB unless they are pummeled. Some of the older 3" with really short magnets, like the 2213A and 123A will typically be around 3 dB down. They go really easily. The old decade woofers (116A and 127A) only had to see an amplifier in the room and they got really nervous.
    reminded me that the 116A was also in the L19 and the 125A from the L40 was similar to the 127A so these speakers should probably have a recharge if they were overdriven hard in prior use?


    Quote Originally Posted by gtimbers
    FYI, the new 1500Al used in the S9800 can take continued pulses of 5000 watts and loose no more than 1%. The test can only be done a few times before the coil is destroyed, but the magnetic assembly is totally stable.
    That's what I call destructive testing. Necessary I'm sure, like crash testing. Do you ever have any photos of what any of these big woofers look like after a test session like that? I don't get out to enough big concerts to see drivers fail like that.

    Thanks Greg, Giskard, and Techbot for helping us understand the physics behind all this.

    Regards,

    Bart
    an 'ol biochemistry major, UCLA '77

  6. #36
    RIP 2010 scott fitlin's Avatar
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    Quote Originally Posted by gtimbers

    Alnico magnets, by their nature are easy to demagnitize with drive. They will not change with time and their dependence on temperature is really small - maybe 1% at 100 deg.F. Alnico stability and resistance to back EMF is really good. This is why they make the best sounding magnetic structures.
    Thank you Greg, for the great info! I have been using JBL 2441 comp drivers since 1979-80, and they always did and still do sound phenomenal. Matter of fact, its my fav comp driver, to me, better than anything else.

    Nice to have serious info on the Alnico subject straight from source!

    scottyj

  7. #37
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    Quote Originally Posted by scott fitlin
    Nice to have serious info on the Alnico subject straight from source!


    ...changes my whole perspective on AlniCo. I'd read numerous articles- yet Greg puts the cigar out in a few choice paragraphs. still so cool.

  8. #38
    Administrator Mr. Widget's Avatar
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    I don't know if Mr. Timbers will revisit this thread, but if he does I am really curious about how neodymium fits into the discussion.

    I'd guess that it is harder to demagnetize, but how does it behave with regards to dealing with back EMF and do it's inherent properties have any sonic consequences?


    Widget

  9. #39
    Senior Member Ducatista47's Avatar
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    Gosh, I work late and look what I miss!

    Time to thank Mr. Timbers again, not only for posting here but for answering my specific question (post #17) in the first sentence. Nine words and my ignorance is put to rest. Spooky, but is this man good or what?

    All the rest of the post did for me was enlighten, entertain and demystify all the issues I ever and never pondered about the subject.

    I am beginning to look at the world in a different, simpler way. He is Greg Timbers, and I am not!

    Again Grateful, Clark in Peoria
    Information is not Knowledge; Knowledge is not Wisdom
    Too many audiophiles listen with their eyes instead of their ears


  10. #40
    RIP 2010 scott fitlin's Avatar
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    Quote Originally Posted by hapy._.face
    ...changes my whole perspective on AlniCo. I'd read numerous articles- yet Greg puts the cigar out in a few choice paragraphs. still so cool.
    Ive always said Alnico sounds best, and you can hear a difference from Alnico to ferrite to neodymium!
    scottyj

  11. #41
    RIP 2010 scott fitlin's Avatar
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    Quote Originally Posted by Mr. Widget
    I don't know if Mr. Timbers will revisit this thread, but if he does I am really curious about how neodymium fits into the discussion.

    I'd guess that it is harder to demagnetize, but how does it react with regards to dealing with back EMF and do it's inherent properties have any sonic consequences?


    Widget
    I`d like to hear what Mr. Timbers has to say about this also!

    I find neo has quite a different tonal sound from either Alnico or ferrite. I`m still using my favorite JBL 2441,s so I guess thats says what my preferences are.

    And I had the TAD 4002,s on the horns again this winter, still didnt like em, not sweet like the JBL, not at all.
    scottyj

  12. #42
    Senior Member JBLnsince1959's Avatar
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    Quote Originally Posted by Ducatista47
    Gosh, I work late and look what I miss!

    Time to thank Mr. Timbers again, not only for posting here but for answering my specific question (post #17) in the first sentence. Nine words and my ignorance is put to rest. Spooky, but is this man good or what?

    All the rest of the post did for me was enlighten, entertain and demystify all the issues I ever and never pondered about the subject.

    I am beginning to look at the world in a different, simpler way. He is Greg Timbers, and I am not!
    I couldn't say it better and it's what I would want to say ( I'm not much of a word person so my posts can be choppy)

  13. #43
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    I spoke to Bill from GPA about this recently. He says a ferrite remag is not necessary and an alnico recharge is recommended only if overdriven.

    All the alnicos I've acquired on Fleabay are recharged since it is not possible to know their history.

    Anyway, I recenlty read that since HF comprssion drivers are not driven with big power, that a recharge for these alnicos is very rarely necessary.

    I suppose this is logical.

    Any thoughts on this?

  14. #44
    Senior Member ratitifb's Avatar
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    Eddy's currents & Coercitive force

    totally agree with that due to coercitive force ratio alnico vs ferrite and magnet circuit design

  15. #45
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    Quote Originally Posted by gtimbers View Post

    Alnico stability and resistance to back EMF is really good. This is why they make the best sounding magnetic structures.

    So do we now have it on good authority that AlNiCo sounds better? Did the value of my all AlNiCo L200/300s just go up? Is this perhaps part of the difference I hear between these and my 4430s? (I've always thought that the L200/300s sound more natural. (All of the AlNiCo components were recently recharged and never played "loud" since that time.)

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