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Topic: Pick-ups 101 |
Jeff Strouse
From:
Jacksonville, Florida, USA
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Posted 23 Jun 2003 2:19 pm |
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Sorry for the elementary question here, but how does a pick-up actually work? What's really going on in there?
For example, what exactly does it mean when people say they have their pick-ups re-wound? Do the insides get loose overtime? Can they be wound too tight or too loose? (I thought I remember seeing in an old post where someone stated that their pickup was wound too tight...). I'm sure this would probably have some affect on tone?? 
I guess I'm looking for the Anatomy and Physiology of an electric instrument. If there are any old posts or websites that would enlighten me with this info, please let me know.
Thanks! |
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Roy Ayres
From:
Riverview, Florida, USA, R.I.P.
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Posted 23 Jun 2003 3:03 pm
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Jeff:
This answer may be criticised as being over simplified and, therefore, full of holes -- but I'll post it anyway. It's a valid question and deserves an answer.
The principle upon which a pickup is based is really quite simple and is as follows:
When a wire is moved through a magnetic field an electromotive force (emf) is produced in the wire. The emf is the force that manifests itself as a voltage at the ends of the wire. (This is the same principle that is at play in an electrical generator.) Similarly, when a magnetic field is "moved" or disturbed an emf will also be produced in any wire located in the magnetic field. In other words, it doesn't matter whether the wire is moved or the magnetic field changes; either will cause the emf to be produced.
A guitar pickup consists of a magnet (or a series of magnets) and a coil of copper wire which is usually wrapped around the magnet or magnets on some sort of spool or frame. So, what you have in a pickup is many turns of wire in a magnetic field. Now, the pickup will just sit there doing nothing unless something disturbs the magnetic field. That's where the guitar string comes into play. When the string is plucked, it vibrates back and forth in the magnetic field and the coil of wire senses the resultant disturbances in the magnetic field and produces an emf that varies at the same rate at which the string is vibrating -- that is, at the same frequency. The emf produced in the coil of wire is sent to the amplifier where it is amplified and used to drive a speaker.
Now, for a more direct answer to your question, if the coil of wire is wound too loosely, each turn of the copper wire will try to move due to forces that are produced between the various turns of wire. The problem with this is that the energy wasted by moving the turns of wire reduces the efficiency of the pickup and affects the tone produced -- usually attenuating the "highs." That is why Leo Fender used to dip his pickups in wax, shellac, or some other substance that would fill in the spaces between the turns and keep them from trying to move. I, personally, know of nothing negative that would be caused by winding a pickup too tightly -- except the danger of breaking the tiny copper wire.
There are three main reasons for having a pickup rewound: (1) a break in any one of the thousands of turns will cause the pickup to quit producing the required emf; (2) one or more shorted turns (one turn touching another due to a loss of the insulating material on the small copper wire) will cause a loss in the "highs" that are produced by the pickup; and (3) the pickup owner wants the pickup rewound in search of a different or better tone.
There are many more factors and considerations regarding pickup design and construction. I have just tried to cover the basics. I hope this helps more than it hinders. [This message was edited by Roy Ayres on 23 June 2003 at 04:08 PM.] |
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Steinar Gregertsen
From:
Arendal, Norway, R.I.P.
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Posted 23 Jun 2003 3:04 pm
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Here's a nice site for you: http://ucsu.colorado.edu/~appela/guitarpickups/
I've often had the single-coil pickups for my strats rewound in order to beef them up a little. Also, the winding can come loose, making the pickup work almost as an ordinary mic, which causes unwanted and uncontrollable feedback. Also, sometimes very old pickups needs to be remagnetized.
That's more or less what I know,- but I think the website may provide you with some knowledge. |
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Brad Bechtel
From:
San Francisco, CA
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Posted 23 Jun 2003 3:30 pm
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Good topic, but it belongs in Electronics. I'm moving it there.
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Brad's Page of Steel
A web site devoted to acoustic & electric lap steel guitars
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