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Degaussing, or "aging" AlNiCo pole pieces

Discussion in 'Just Pickups' started by Antigua Tele, Feb 17, 2018.

  1. philosofriend

    philosofriend Tele-Holic

    832
    Oct 28, 2015
    Kalamazoo
    Thanks for the info. Gives me hope for being able to adjust non-adjustable pickups to get all the strings equally loud. Yay!
     
  2. Barncaster

    Barncaster Doctor of Teleocity

    To the original premise of this thread, I’m in agreement. I don’t think there is validity to the concept of degaussing magnets to sound like vintage magnets. It’s based on the incorrect assumption that vintage instruments sound great partly because their pickup magnets have naturally degaussed over time to some level that makes the pickups sound really good.

    Alnico is classified as a permanent magnet material per Bill Lawrence. This means it may only lose a few percent of its gauss level over a century. In our industry, we are talking about 70 years max so I don’t think time is in play here.

    I think the real issue here is very complex. In my testing, the impact of gauss levels on Fender style single coils is much more critical than on PAF style humbuckers. The real issue is Alnico 5 rods. A typical Alnico 5 rod will saturate at about 1600 gauss which is about double of Alnico 2, 3 and 4 due to a special heat treating process which aligns the magnet’s crystallinity along its magnetic axis (anisotropic).

    It seems more recent pickup manufacturers have treated charging A5 rods with as if the were like the isotropic grades (A2, A3, A4) which saturate in the region of 800 gauss and sound reasonably OK there. It’s a very interesting experiment to hear the tonal differences of a Fender style single coil with different magnet array gauss values. To my ears there is a radical difference in tonality in relation to gauss levels. A Fender style single coil equipped with a saturated array (approx 1600 gauss) sounds really bad.
     
    Derek Kiernan likes this.
  3. Antigua Tele

    Antigua Tele Friend of Leo's

    Jun 2, 2014
    west coast
    In my testing I've found that magnetic string pull has a complex effect upon the tone. I've recorded string plucks with the pickups set close, and then set far away, and then I looked at the differences it causes in FFT analysis, where the amplitude intensity of each harmonic can be seen http://guitarnuts2.proboards.com/thread/7998/tonal-effect-pickup-height. Everyone knows that really strong pull causes "stratitus", but even when the effect is no so strong as to be undesirable, there is an effect. The reason the effect is so complex is because the pull upon the string, in a particular location along the length of the string, causes a shift in energies between the harmonics levels. For example, if the pickup is pulling at the anti-node of the third harmonic, it will make the third harmonic louder, while causing other harmonics to become quieter. The effect is also not instantaneous, it changes over time, as energies shift between levels, producing a beating and some harmonic levels, while leaving others untouched.

    In general, the farther the pickups are away from the strings, the more "naturally" they vibrate. The closer the pickups to the strings, the more interference that is caused by the pickups. AlNiCo 2 is reputed to have a different tone in general than AlNiCo 5, be it with humbuckers or Strat single coils, and so for the reason stated, I would say AlNiCo 2 is associated with natural string movement, while AlNiCo 5 is associated with disturbed string movement. If you set a piuckup with AlNiCo 5 very low, its pull upon the strings will be weak enough that it effects the strings as little as does a pickup with AlNiCo 2 that has been set closer.

    Regarding AlNiCo 3 and 4, just take a look at any AlNiCo datasheet and you can see that they're barely any different from AlNiCo 2 in nearly all performance measures. AlNiCo 3 is like a slightly worse AlNiCo 2 that was devised in response to the high cost of cobalt. As a part time rationalist, part time subjectivist, I don't believe there is any meaningful difference between them in the guitar pickup context.

    Regarding AlNiCo 5, I do measure around 800G with lower AlNiCo grades, but I've tested dozens of AlNiCo 5 Strat pickups and find that usually read 1050G on center, a little higher at the edges. Part of that is because the adjacent return paths cut the Gauss down by about 100G, so if the pole piece is free standing, it measured around 1150G. When freshly charged with a neo measuring about 3,500G, the A5 pole piece measures ~1250G, and settles down to 1150G after about five minutes or so. I've never been able to get Strat/Tele type A5 pole pieces up ~1600G.
     
  4. highwaycat

    highwaycat Tele-Meister

    Age:
    30
    434
    Jun 15, 2017
    California
    I'll just stick with setting my noiseless singlecoils very low. Couldn't be happier.
     
  5. Antigua Tele

    Antigua Tele Friend of Leo's

    Jun 2, 2014
    west coast
    kingvox, Steve Holt and BorderRadio like this.
  6. Steve Holt

    Steve Holt Tele-Holic

    938
    May 29, 2016
    Kansas
    I put it in my amazon wish list. Which is a sure way to make sure I never get around to buying one!
     
  7. fraser

    fraser Tele-Holic

    862
    Sep 8, 2007
    Hamilton, Canada
    I’ve played around with this myself, though with a whole lot less science lol.
    I have swapped a pickups polarity around by degaussing it then charging it with an opposite polarity.
    To achieve hum cancelling in strat pickups.

    I took 2 magnets out of an old pc hardrive, set them on the jaws of a vice, and passed the pickups through the field created between them.

    A side effect was, that I was unable to recharge them back to original magnetic strength.
    And the altered pickups sounded much sweeter than before.
    So I run the other 2 pickups of the respective sets thru, then recharge back to original polarity.

    Really made a difference with the pickups I did
    Was a free and easy way to improve a cheap set of pickups to my ears.

    I remember at the time looking it up on the net, and there was a lengthy discussion someplace about this, don’t recall the forum, but it wasn’t here or anywhere else I’ve hung out.
    There were guys chiming in saying they’d done this since the seventies on new guitars, basically just passing a strong magnet over the pickups until they sounded better.

    Had I not experienced it for myself already, that thread would’ve seemed absurd lol.
     
    Last edited: Dec 8, 2018 at 9:52 PM
    CFFF likes this.
  8. Antigua Tele

    Antigua Tele Friend of Leo's

    Jun 2, 2014
    west coast

    Hard drive magnets would be too small, and if you have some neos that are larger, the vice technique is not a good one, because you should be pulling the AlNiCo away from the neo, remaining on axis as you pull away. When you pass the alnico through the axis, the return path of the neo will demagentize the alnico again, especially in the vice configuration.

    Simply passing a neo over the top of the pickup works, but the issue there is knowing how much change youve made because a neo is so powerful that it will completely flip the polarity of the alnico in an instant. You'd want to have a meter like the WT10A in order to keep track of what's happening. If you go by ear, you might like the results, but you wont really be sure what has happened, because the difference is very subtle, it's not night and day, it's barely even an night and dusk.
     
  9. fraser

    fraser Tele-Holic

    862
    Sep 8, 2007
    Hamilton, Canada
    Yes, good points. But it isn’t really something I’m interested in exploring, just some observations.
    I have a bunch of good neo magnets around, if I need to reverse a pickup in the future I’ll use those.
    But the ones I did are still sounding nice, and I believe I did them almost 10 years ago.
     
  10. kingvox

    kingvox Tele-Meister

    203
    Mar 23, 2017
    CT, USA
    For anyone interested in pickups, I do think the WT10A that Antigua mentioned is a good investment. Another good investment would be some neodynium mags for re-magnetizing. Then you can experiment to your heart's content.

    I've experimented quite a bit with this, but would have to go back and record the results. Even then it would be tough to compare. I think the most accurate way would be to degauss the poles while they're mounted in the guitar, after recording some tracks with the magnets at saturation. Record the Gauss for both cases. It would just ensure that the pickup height remains identical for the A/B comparison.

    Using a decent audio interface, you should be able to track the actual dB output of the signal as well. Keeping the preamp gain on the interface consistent, any differences should be pretty easily observable.

    I know from winding pickups that many, many times, things I thought would make a huge difference ended up being so subtle as to be almost unnoticeable. And recording, with all its imperfections, is still IMO, the best way to go for comparisons.

    You can put on some headphones or set up some studio monitors, and alternate the tracks while you listen. You can even do this blindly, so you forget which track is which, and that's when the subtlety of the differences really hits you. It's pretty hard to be biased when you can't even tell which track is which, and you have to listen very, VERY hard to see if you can actually tell any difference between the two tracks.

    Intentional degaussing can be a nice way to balance string to string volume. I've always felt that the Low E is way too loud, as well as the G string, with the D and high E strings tending to be weaker.

    Then again, even that's all down to personal preference. Degaussing is slightly tedious, but does give you some more fine-tuned control over your sound if you're using Alnico rod pups. Just be sure to have some neo mags on hand for starting back at square one in case you don't like the results ;)
     
    CFFF likes this.
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