General question about slug magnet length

Discussion in 'Just Pickups' started by milocj, Mar 4, 2017.

  1. milocj

    milocj Friend of Leo's Ad Free Member

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    I have to modify a Rickenbacker toaster to fit an old Rickenbacker neck position that doesn't have routing for the slugs (they used to use shorter slugs in the neck). As a general rule, what difference is there between otherwise identical pickups that used two different lengths of alnico V slugs?

    The bridge position and all current toasters have magnets about 1- 1 1/8" long and the necks used to use approx. 5/8" long magnets. All the extra length is below the bobbin. Just wondering what the difference is if I pull and replace the slugs with the correct length.
     
  2. Spirit1066

    Spirit1066 TDPRI Member

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    I can't help you with an explanation, but I would mark the slugs with ink and touch the bottom with it, then just drill out to accommodate. Rather than take both apart mate.
     
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  3. Antigua Tele

    Antigua Tele Friend of Leo's

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    Since the permeability of AlNico is rather low, the difference mostly comes down to flux density.

    Looking at the height and diameter of the Toaster pole pieces, I'd bet the AlNiCo poles of the bridge pole pieces are somewhat stronger than the neck pole pieces, due the additional length, relative to the diameter. The main tonal difference is that stronger magnets are perceived to produce a sharper attack and tighter bass, while weaker magnets are perceived to have a "softer" attack and a "warmer" low end. You can compensate to some degree by setting the pickup higher or lower, to increase or decrease the magnetic strength by virtue of distance from the strings.

    This is all very similar, if not identical to, to the difference you observe when you have Tele or Strat pickup that feature similar inductance values, but one pickup uses AlNico 5, and the other uses AlNiCo 2 or 3, because AlNiCo 5 has almost twice the flux density of AlNiCo 2 or 3, which you could also achieve by using longer pole pieces. A caveat is that the inductance of the coil weighs heavily. this notion that AlNiCo 2 or 3 are "warmer" or "softer" than AlNiCo 5 presumes a pickup has a moderate resonant peak, where as if a pickup is especially "hot" wound, or especially "low" wound, those "warmer" and "softer" adjectives become less accurate.

    Given all the many variables, it's impossible to tell how the sound will differ. Best case is that it wont sound any different, worst case is that the pickup will be very subtly softer, and less bright. I think it would be fine to go with the shorter pole pieces. I think the guitar would still sound very jangly overall.
     
    Last edited: Mar 4, 2017
  4. Derek Kiernan

    Derek Kiernan Friend of Leo's

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    Typically you would want longer poles in the neck position for the increased magnetic length, but nothing is in isolation, and preferences vary.
     
  5. Antigua Tele

    Antigua Tele Friend of Leo's

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    I don't think that's true. There's not really a need to "reach" for the strings at the neck, because the string displaces so much more, that there is a greater induced voltage in the neck, all other things being equal. That's why neck pickups are usually "underwound", by the same virtue, they can more easily get away with a weaker magnet coupling to the strings and still achieve a balanced output.
     
  6. milocj

    milocj Friend of Leo's Ad Free Member

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    Thanks for the info guys. Typically, Rickenbackers seem to have louder neck pickups, though I'm not sure if that's due to the fifth pot or not (which I'm eliminating on this one until I see if I can get away without it for stereo blend.

    Regardless, the earlier toasters used short magnets in the neck position and aren't routed for the slugs. They also no longer make the replacement without protruding slugs. I specifically wanted the earlier 21 fret version due to a lighter top and lighter bracing so the narrow channel rout for the slugs is a last resort because I don't know if it weakens the neck joint, and I have no problems with my other two '60s versions.

    I already know what this new replacement pickup sounds like and was wondering what may change.
     
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