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How Pickups Work

Discussion in 'Pickups & Electronics [BG]' started by daveze, Aug 13, 2003.


  1. After the discussion I had with Geshel about the exact physics that determines how pickups work (the topic about gold wiring), I have become a little more confused at how the pickup works in practise.

    What I'm looking for is a simple deconstructed pic of a pickup, if possible for the different kinds as well. I've been looking for one for a while and everytime I think I've found one, its either too complex and not orientated at describing how they work, or its a dead link.

    I tried a search but it didn't turn up didly.

    Josh D
     
  2. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    I don't have a picture, but a pickup is basically a coil of wire wound around a magnet. The steel strings vibrate in the magnetic field causing a change which induces a current in the coil which appears at the output jack as a voltage for the amp to amplify.

    Clear as mud?
     
  3. I have a pretty good understanding of the physics involved in the pup. Its the actual workings that I don't completely understand.

    Standard pup is like the two flat, non-conducting plates that hold the pole pieces in place. The pole pieces are magnets, all with the polarity in the same direction. The coils are just copper wire (42-43 gauge? I don't really know what that means but if I was buying the stuff I imagine it'd be labelled).

    My big questions are: 1, Do the coils come into contact with the poles? 2, Do the coils have to be uniform in the wrapping, or can they just be wound so that its pretty much right? I ask this cause if I was going to wind it so its uniform I'd need something to make that happen, something to move the wire source with respect to the pup. 3, Do the pups need to be wax dipped (or equivalent) and should the wax end up between the poles if I do dip them? 4, How do other pickups look, I've read enough single coil descriptions but less on the others, P's, the blade ones, lipsticks, different kinds of humbuckers.

    Josh D
     
  4. BillyB_from_LZ

    BillyB_from_LZ Supporting Member

    Sep 7, 2000
    Chicago
    The gauge number of wire gives a hint at its diameter. The larger the number, the smaller the wire. 42 Ga. wire has a nominal diameter of just 0.064 mm, about the thickness of medium weight human hair.

    The coil does not need to touch the pole pieces, in fact, based on the dimensions that I gave you, you probably wouldn't want it to. Coils are wound on bobbins, a mechanical form that helps support and protect it from damage.

    Even winding is the best way to go. It is said that original Gibson PAF pickups sound better because they weren't wound as carefully as later versions. However, even winding will support the fragile magnet wire better and hopefully prevent breakage within the coil.

    Wax dipping helps hold the outer wrappings in place and helps prevent microphonics (usally presented as feedback because the outer windings vibrate (physically move) thereby inducing a current in the coil). You want a structure that is solid and immune to vibration as we bassists create a lot of that!!!

    The basic construction is the same, coil of wire around a magnet. A P pup is really two single coil pups out of phase to reject hum, my guess is that a lipstick pickup is just like a single coil in a metal can. Humbuckers can take on several different configurations with coils side by side and magnetically out of phase or stacked vertically. The theory is that hum will excite both coils equally and since they're out of phase, the signal will be cancelled. The signal that the string excites the pickup with is not so uniform so it doesn't get cancelled out completely. Humbuckers do tend to be darker sounding because of increased inductance (two coils) and some cancellations.
     
  5. JP Basses

    JP Basses

    Mar 22, 2002
    Paris FRANCE
    you should just buy and read Jason Lollar book about pickup winding...it pretty much covers all you questions ;)

    Alaso check the pickup makers forum

    Peace, JP
     
  6. I think I may have to bite the bullet and get the darn book. Now I've gotta find an easy way to get it here, and the money to pay for it. Anybody in need of tutoring for maths or any of the sciences?

    Josh D
     
  7. rumblinbass

    rumblinbass

    Aug 22, 2003
    Wimberley, TX
    Pup's are based on Faraday's Law that was explained in an earlier reply (sorry can't remember who it was). If you want to do a search, search "faraday's law", or posibly look on howstuffworks.com. I was looking for the same thing a while back, but I can't remember exactly what I did a search on.

    If you are looking for an explanation look in any physics book...that's where I learned how they work.

    As far as I understand, the magnets (which are usually Alcino5) are wrapped in magnet wire. Magnet wire is insulated and can be found at Radio Shack.

    The gauge of wire and number of coils affect both the output as well as the output impedance of the pups.
     
  8. rickbass

    rickbass Supporting Member

    Super book if you really want to know. Also, I got Erno Zwaan's book, "Animal Magnetism for Musicians" which mainly deals with pups and basses and has pickup building projects.
     
  9. I should be able to have the book within the next month, I've picked up some tutoring work, so theres some more spare cash with me.

    Whats the bobbin made out of, and how far from the poles should it sit, or should it sit against the poles? I'm thought experimenting with the idea and it'd sit against, cause otherwise you end up with the coils further from the poles, which means there is less output and different tonal properties (unless of course thats what I want). Plus it'd be a smidge harder to have them sit off, I'd need to use something with some strength for the bobbin.

    I gotta get more credit for my phone, more fuel for the car but after that I'll be seeing where I can pick the book up from. What places would be more likely to stock it? I'm going to try the regular bookstores and as many music stores as well but I'm thinking I'll have to order it in.

    Josh D