Magnets on speakers

rebuy
rebuy Posts: 695
edited February 2012 in Speakers
Just doing some reading up on magnets and got to wondering what kind of magnets Polk uses.
Anyone know? Could not any info anywhere about this.
Post edited by rebuy on
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  • thesurfer
    thesurfer Posts: 574
    edited February 2012
    Dont know myself, but they seem to be pretty beefy, from the drivers ive seen.
    Not an Audiophile, just a dude who loves music, and decent gear to hear it with.
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  • rebuy
    rebuy Posts: 695
    edited February 2012
    Polk might be using conventional ceramic-ferrite magnets on home speakers since they don't advertise using special magnets except for tweeters which use neodymium. Some of the car speakers use them also.
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  • thesurfer
    thesurfer Posts: 574
    edited February 2012
    rebuy wrote: »
    Polk might be using conventional ceramic-ferrite magnets on home speakers since they don't advertise using special magnets except for tweeters which use neodymium. Some of the car speakers use them also.
    Not sure, but i use a pair of RT25i,s in one of my 2 channel rigs, and the magnets are pretty big for there size, the guy that reviewed the 25i,s in stereophile liked em so much, he bought the pair he reviewed.
    Not an Audiophile, just a dude who loves music, and decent gear to hear it with.
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  • BeefJerky
    BeefJerky Posts: 1,320
    edited February 2012
    It does seem to vary. But, as rebuy said, if it doesn't mention any type of special magnet, it's just probably just an inexpensive ceramic-ferrite type.

    I know that the SR-series component systems do use neodymium magnets on the mid-woofers. I remember looking at the magnet on the SR5250 mid-woofer and thinking how small and light the magnet was, but that's part of the reason for using them.
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  • thesurfer
    thesurfer Posts: 574
    edited February 2012
    Yes, hard to say, ive always heard, the bigger the magnet, the more power it can handel, as opposed to a smaller magnet made of same material, id just call pcs, and ask them, then you well know for sure.
    Not an Audiophile, just a dude who loves music, and decent gear to hear it with.
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  • Face
    Face Posts: 14,340
    edited February 2012
    thesurfer wrote: »
    Yes, hard to say, ive always heard, the bigger the magnet, the more power it can handel, as opposed to a smaller magnet made of same material, id just call pcs, and ask them, then you well know for sure.
    Not completely true.
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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  • mhardy6647
    mhardy6647 Posts: 33,990
    edited February 2012
    The flux density in the gap is probably the most important parameter in terms of the "strength" of the electromagnetic motor in a loudspeaker driver. The linearity (or uniformity) of the field is also very important. Design and geometry of the motor is generally more important than magnet weight/strength per se.

    Neodymium magnets are much stronger on a weight basis than the common ceramic magnet materials. Us old guys tend to be fond of AlNiCo (alloy of aluminum, nickel, and cobalt) magnets - but other than some interesting nonlinearity properties, most of that allure is probably the cult of the arcane.

    Arguably the BEST magnet to use for speakers - and the approach used in the early days, and still available from some esoteric manufacturers today - is an electromagnet. The primary drawback is the need for a high-power DC power supply to energize the electromagnet.

    And there are numerous types of drivers that don't even use magnets (primarily electrostatics and piezoelectric transducers).
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  • thesurfer
    thesurfer Posts: 574
    edited February 2012
    Face wrote: »
    Not completely true.
    I didnt say that was a fact, read my post, i said Thats what ive heard,,
    Not an Audiophile, just a dude who loves music, and decent gear to hear it with.
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  • VR3
    VR3 Posts: 28,782
    edited February 2012
    Wanted to comment that Polk puts a bucking magnet + cup around their magnets so they are not nearly as big as you think ;)
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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  • Face
    Face Posts: 14,340
    edited February 2012
    mhardy6647 wrote: »
    The flux density in the gap is probably the most important parameter in terms of the "strength" of the electromagnetic motor in a loudspeaker driver. The linearity (or uniformity) of the field is also very important. Design and geometry of the motor is generally more important than magnet weight/strength per se.

    Neodymium magnets are much stronger on a weight basis than the common ceramic magnet materials. Us old guys tend to be fond of AlNiCo (alloy of aluminum, nickel, and cobalt) magnets - but other than some interesting nonlinearity properties, most of that allure is probably the cult of the arcane.
    And although neo magnets are stronger, they can have lower power handling due to less mass to dissipate heat.
    "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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