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Thread: Difference between ceramic & AINiCo speakers

  1. #1
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    Difference between ceramic & AINiCo speakers

    Looking to put together a cabinet from Weber. Looking at 4 10's for a Vox AC15 clone and 5E3 I've recently built.

    1) Is Weber a good place to go for speakers/cabinet, speaker being the most important componant.

    2) What is the difference between ceramic & AINiCo speakers?

  2. #2
    Senior Member TD_Madden's Avatar
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    Difference in Ceramic vice AlNiCo

    From Ted Weber's "Let's Talk Speakers":

    OK, let's start with basics. What are the main differences in sound between comparable speakers, one with a ceramic magnet, one with AlNiCo? Also, how does the size of the voice coil affect the sound.

    Jeff, good questions. The whole 'AlNiCo mojo' is about smooth compression at high average levels, such as what you would have running the amp flat out. AlNiCo (Aluminum-Nickel-Cobalt) is an alloy magnet and all alloy magnets are easier to demagnetize than comparable Ceramic (Strontium Ferrite) magnets. What this means is that as the voice coil starts moving in response to the input signal, it generates a magnetic field of its own that tries to demagnetize the magnet. As its effect lowers the available magnetic field of the AlNiCo magnet, the speaker becomes less efficient, the voice coil moves less, etc. The physics of it is that the small magnets near the surface of the magnet poles (called 'domains') begin to change state, or flip directions. The result is smooth compression, the same kind of operating curve compression that occurs in a tube amplifier. The ceramic magnet, on the other hand, doesn't compress or demagnetize as easily, so the voice coil moves to its mechanical limit and won't go any farther. This is why some players say ceramics sound a little edgey at high average levels as opposed to AlNiCo. However, by properly designing the entire magnetic circuit, Ceramics can be made to behave quite well for desireable guitar amp tone and dynamics. You might compare the two magnetic circuits to solid state amps versus tube amps, where the solid state amp gives it all its got then clips hard, while a tube amp compresses nice and smooth. The extension of this idea, then, is that with the AlNiCo, like the tube amp, you can seem to have a louder average volume since it gets compressed smoothly. By the way, the compressing or demagnetization that occurs with the AlNiCo is not permanent. It springs right back to its design operating point.

    A voice coil is like an electric motor. The bigger the voice coil, the more wire used, the more torque or pulling power you have to move the cone. With the proper match of components, you can get more sensitivity, wider frequency response, and more power handling ability.

  3. #3
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    This particular Weber answer is wrong. If the magnetic domains start changin direction, that´s not a "compression" mechanism but plain demagnetizing, which by the way is irreversible without paying a visit to the factory´s Big O´l magnetizer. I think that the percieved compression of old alnico speakers lies more in the very short coils: when it starts leaving the very short gap, you´ll see *real* wavetop rounding.

  4. #4
    Noodle of Reality Steve Conner's Avatar
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    I was never sure if I believed that thing about Alnico magnets "compressing" either. But according to the second link, it will compress and recover again fine. It won't be permanently affected unless you hit it with a field bigger than the coercive force.

    And according to the first link, Alnico magnets are a good order of magnitude "squashier" than ceramic or neo. So I guess there may be truth in it.

    http://hyperphysics.phy-astr.gsu.edu...s/magperm.html
    http://www.magnetweb.com/Sect1C.htm

    I also agree that the short voice coils have a huge influence on the sound, but there are plenty of ceramic speakers with short voice coils too.
    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

  5. #5
    Music Lover Sock Puppet's Avatar
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    Thanks Steve, that certainly cleared things up for me.

    S.

  6. #6
    Pickup Maker David Schwab's Avatar
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    Quote Originally Posted by Steve Conner View Post
    And according to the first link, Alnico magnets are a good order of magnitude "squashier" than ceramic or neo. So I guess there may be truth in it.
    Well that's certainly true of the magnets in guitar pickups. Alnicos have a softer field and do sound "squashier".

    I made some bass humbucking pickups, and was able to swap magnets. An Alnico magnet sounded warm and mushy... very vintage, the same size ceramic was brighter, louder, and had more dynamics. Then I swapped in a smaller but way more powerful N38 Neo.. and it was way louder, brighter and punchier. So besides the "harder" magnetic field, you have more "juice" to work with.
    It would be possible to describe everything scientifically, but it would make no sense; it would be without meaning, as if you described a Beethoven symphony as a variation of wave pressure. — Albert Einstein

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  7. #7
    Noodle of Reality Steve Conner's Avatar
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    Hi David,

    Your experiment sounds pretty cool apart from one thing. According to my understanding of things, the compression due to Alnico magnets should only be noticeable when the change in magnetic field (caused by voice coil current, string movement, etc) is the same order of magnitude as the field strength of the magnet itself.

    That happens in a speaker, where we have dozens of turns of wire with several amps of current getting pumped through them. But I don't see how it can happen in a pickup, where the perturbations in the field caused by string movement are so much smaller. You can prove this to yourself by pondering whether a pickup can drive a speaker directly with no amp. I doubt even your neo bass pickups could

    BTW, reading the stuff you and others post on the Pickup Makers forum is really inspiring! I'd love to try one some day with blade polepieces made from a transformer core, and neo magnets.
    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

  8. #8
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    So how do you think the new Scumback alnicos with the neo insert would fit in the mix?

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