pickups

[Ulyanov]

I was wondering how different pickups worked,
like single coil, split coil, that kind of thing, and how they sound.

[Blackbird]

Welcome to TalkBass, Ulyanov.

Check the Pickups forum, where your post will be moved eventually.

Will C.

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I'm not a genius. I'm just a hard working guy.
-BW

[throbbinnut]

The way all standard electromagnetic pickups work is based on the fact that when a coil of wire is wrapped around a magnet, and a string vibrates in the magnetic field, a voltage is induced in the coil of wire that is proportional to the displacement of the string, and the frequency of the voltage is the same as the frequency of the string vibration. This is the same idea that motors, speakers, microphones, etc. are built around, and that is that electricity and magnetism are all tied together in the scheme of things. You can use one to create the other. So the pickup changes mechanical vibrational energy into electrical energy. That's called a transducer.

Now, Single Coil means that there is just one coil wrapped around the magnet pole pieces. This is the simplest design, but it picks up any hum from stray magnetic fields around. The next improvement was the humbucker. There are a few different ways to mechanically set it up, but the idea is that you build 2 identical single coil pickups, but you wind one of them in the direction opposite the other. This will cause the 2 coils to put out voltages that are 180 degrees out of phase with each other, so if you hooked the coils together one way, you would get no string sound since it would cancel out, and you would get double the hum, but if you reverse the leads for one of the pickups, now the string signals from the 2 pickups are in phase and add, and the hum signals from each single coil pickup cancel each other out. Voila, hum-bucking. The term bucking comes from an old electrical term where a transformer coil can be hooked up as "bucking" or "boosting", where bucking means hooking up out of phase so the voltage is lower, and boosting means hooking up in phase so the volatage is higher.

More than you ever wanted to know.

As for sound, humbucking tends to lose a little treble, since the 2 signals when added are accidentally cancelling out some of the high frequency content by way of phase differences. Single coil is probably a more true representaion of the string vibration, but they hum like a mofo. You really need to hear them to tell the difference, but you can easily tell a difference when heard.

I like 'em all.

Chris

[Ulyanov]

thanks. anyone know how a split coil works?

[username1]

in a humbucking dual coil the 2 coils are wound out of phase to cancell the hum but the magnets are backwards to each other to put the string sound back in phase. In a split coil only half of the pickup is wound one way and half the other with the magnets also reversed on half the strings. This cancels the hum but retains the single coil sound. A P-bass pickup is also a good example of this.

[username1]

I thought i should also mention that the shape of the coil also affects the sound. In a jazz bass for instance the pickup is higher but narrower. This puts the windings closer to the magnets and also requires less wire for the same amount of turns. The effect of these coils is a wider frequency respose with a more high fidelity sound. A p-bass is just the opposite. It has a coil that is not very high but wound alot wider on the bobbin. This induces more capacitance into the coil and the resulting sound is punchier with the trade of being a narrower frequency response but with more punch in the low end.