Wot “magnetized” and “unmagnetized” magnets?

Discussion in 'Tele Home Depot' started by Verzila, Apr 14, 2018.

  1. Verzila

    Verzila Tele-Meister

    Posts:
    144
    Joined:
    Dec 21, 2012
    Location:
    WR15 8PH, United Kingdom
    Shopping around for replacement magnets for a P90 pickup, I see some sellers offer “magnetized” and “unmagnetized” options. Can someone shed any light on what this means? Surely “magnitised” is the whole point, and I’m guessing that by “unmagnetized” they’re not talking about selling just a flat piece of metal? :)


    Cheers
     
  2. Verzila

    Verzila Tele-Meister

    Posts:
    144
    Joined:
    Dec 21, 2012
    Location:
    WR15 8PH, United Kingdom
    And while I'm at it, what are the benefits / drawbacks of "unorientated" (I'm guessing this means it doesn't matter which way you insert it into the pickup) and "rough cast"?
     
    old wrench likes this.
  3. eclecticsynergy

    eclecticsynergy Tele-Afflicted

    Posts:
    1,377
    Joined:
    Nov 16, 2014
    Location:
    Albany NY
    They're offering the right grade of alloy in the right size, for those would would rather charge the magnetic field themselves. Some do, especially pickup makers who might not want the magnet fully charged.

    For most of us, ordering them charged is the only way to go because we don't have the right equipment to charge them, or the (even more expensive) equipment required to accurately measure the end result. A good gaussmeter isn't cheap.
     
    old wrench and Verzila like this.
  4. eclecticsynergy

    eclecticsynergy Tele-Afflicted

    Posts:
    1,377
    Joined:
    Nov 16, 2014
    Location:
    Albany NY
    Unoriented is a confusing term- it can lead some to think that unoriented mags do not have North and South poles, but they most certainly do. It refers not to absenc of polarity but to the orientation of individual molecules within the magnet. In an oriented magnet they are all aligned. This give oriented magnets a much stronger field when fully charged. In an unoriented magnet, the alignment of the molecules is random- they point every which way. This makes unoriented magnets weaker, and their magnetic fields more diffuse, which in a guitar pickup affects the tone as well as the output.

    Oriented magnets receive an extra step in the manufacturing process: they are exposed to a powerulf magnetic field when they're still liquid, which causes the molecules to align themselves; they then are frozen in that orientation when the material solidifies.

    Alnico 2, 3, and 4 are always unoriented because of the nature of the alloys. Alnico 5, 6, 8, and ceramic 5 & 8 types are normally oriented (anisotropic) but some are available in unoriented forms. I really like UA5 magnets, especially in bridge position but also in the neck. They are noticeably quieter than regular A5 though.

    A fact that was little-known until fairly recently is that UA5 magnets are the tone secret of the old Gibson Shaw humbuckers. Everybody thought they were A2. But when pressed, Tim Shaw says UA5.

    I've heard of unoriented C8 magnets, but they're so much weaker than their oriented counterparts that they're rarely used in guitar pickups.
     
    Last edited: Apr 14, 2018
    Bob.M, aerhed, old wrench and 2 others like this.
  5. eclecticsynergy

    eclecticsynergy Tele-Afflicted

    Posts:
    1,377
    Joined:
    Nov 16, 2014
    Location:
    Albany NY
    Rough cast is just as it sounds; a rough, grainier outer surface as opposed to a smooth polished one. The tone difference is more subtle, affecting mostly the high treble and attack (rather than the overall character and/or volume the way swapping to unoriented or a different grade of alnico would). Some prefer polished at the neck and roughcast at the bridge; it has perhaps a little less of the "icepick" treble and biting attack. But the difference is not extreme- a roughcast A5 is still capable of sparkle and chime.

    Many prefer the sound of Seymour Duncan 59s in their vintage 70s-early 80s form (they originally had different magnets that are very dark in color), and swapping out the modern polished A5 mags in favor of roughcast A5s brings them closer to the originals.

    Some have compared the polished vs rough difference in humbuckers to covered vs uncovered. I don't subscribe to that comparison myself because covers can vary quite a lot, making more or less difference in the tone depending on what they're made of, how thick the material is, how powerful the pickup is, and what kind of mag is inside.
     
    Last edited: Apr 14, 2018
    old wrench, Mincer and Verzila like this.
  6. guitarbuilder

    guitarbuilder Doctor of Teleocity Silver Supporter

    Posts:
    19,974
    Joined:
    Mar 30, 2003
    Location:
    Ontario County
    Last edited: Apr 14, 2018
    old wrench likes this.
  7. Telenator

    Telenator Doctor of Teleocity Vendor Member

    Posts:
    13,099
    Joined:
    Sep 19, 2005
    Location:
    Vermont
    It's a lot better to build pickups with uncharged magnets. You'd be amazed how much magnetic material a charged magnet will pick up all by itself. Makes assembly very difficult in some instances.

    Personally, I like the sound of covered bar magnet humbuckers too. I often put chrome covers with no holes in them, on the pickups in my project guitars. They sound great. A little woolier. afL6-S Project 005 lo-res.jpg
     
    old wrench likes this.
  8. Barncaster

    Barncaster Doctor of Teleocity

    Posts:
    10,827
    Joined:
    Feb 3, 2010
    Location:
    Northern California
    Hey Verzila,
    There is no small, simple answer to this so we’ll stick to P90s per your original question.

    From a dimensional perspective, you’ll want magnets listed with a 2.50” length. P90s take two and like magnet poles are oriented towards the keeper which the pole screws pass through.
    If you don’t have a neo array set up for charging and known gauss preferences for your specific builds, naturally go with pre-charged. Specific gauss level is much less of an issue with P90s and PAF style humbuckers than Fender style single coils.

    From an Alnico grade perspective, A2 in the bridge is thick and glorious like Leslie West. If you want more clarity A5 is excellent as well.

    For the neck, I don’t like P90s at the stock wind level. If you have to have a P90 in the neck, always go A5. To really optimize and make a P90 work in the neck, underwinding is mandatory. Purchase 2.50” rough cast, charged A5s and from a magnet perspective you’ll be good to go. Combine an underwound coil and A5 magnets and a P90 will really start to respond in the neck position. YMMV.
    Rob
     
    Last edited: Apr 15, 2018
    oldfish and old wrench like this.
  9. old wrench

    old wrench Tele-Holic

    Posts:
    757
    Joined:
    Feb 2, 2017
    Location:
    corner of walk and don't walk
    Man, there is a ton of info in this thread; I'm glad I checked it out!

    I've always really dug the sound of P-90s. That's part of my affinity for Gibsons.

    I'll have to check the magnet type in the underwound "Tele" Fralin neck pickup I've got; it's got a very nice sound to it.

    Edit: I just checked Fralins website and he apparently employs A-IV magnets in the P-90s.
     
    Last edited: Apr 15, 2018
  10. eclecticsynergy

    eclecticsynergy Tele-Afflicted

    Posts:
    1,377
    Joined:
    Nov 16, 2014
    Location:
    Albany NY
    A3 is another good mag for neck P90s, often overlooked. It is similar in overall character to A2, but with less low end and less output.

    I like A4 also. It has sort of a dual personality- sparkle when clean and grit when driven.
     
  11. Barncaster

    Barncaster Doctor of Teleocity

    Posts:
    10,827
    Joined:
    Feb 3, 2010
    Location:
    Northern California
    I have a 47' P-90 in my stash. At the time, Gibson was building the P-90 like a Fender-style pup with rod magnets and flatwork. If you want to do an interesting experiment, you can drill out a P-90 bobbin with a 3/16' drill bit and glue in rod magnets and forget all the bar meanets, screws, pole pieces and keepers. Get the recipe right and they sound fantastic!
     
  12. Telenator

    Telenator Doctor of Teleocity Vendor Member

    Posts:
    13,099
    Joined:
    Sep 19, 2005
    Location:
    Vermont
    The magnets need to be really short in a P90 or they overwhelm the wind and the pickup becomes painfully bright.
    I wouldn't go much shorter than .420 though or the magnet starts to suffer from being too short vs it's diameter to maintain a N/S orientation.
    It does sound great when you get it right though.
     
    Last edited: May 5, 2018
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.