Magnetic Guitar Pickups, ‘How’d They Do That?’

With the SC community beginning to expand into new horizons, it’s my honor to bring you this, the first installment in a series of articles focussed on the technical aspects of guitars. I have grand plans for articles covering electronics, tonewoods, getting the most out of a guitar, set ups, and even elements of guitar construction. You can expect both light reading acticles like today’s, as well as in depth detailed information with photographic support.I thought I’d start our journey with a nice light historical article on a topic that I’ve always found fascinating. Guitar pickups have revolutionized the way that we make music. While most of us weren’t around to witness the catalyst of this change, we’ve all seen first hand how music has evolved as a result. I’d like to shed a little light onto their history, how these wonderful inventions work, and offer some advise on how to go about getting YOUR sound out of them.

Development

While there are many different types of pickups available today, the passive magnetic pickup is undeniably the industry mainstay. They are the driving force in everything from jazz, to rock, to NUmetal (uggh). The first known magnetic pickup was created by George Beauchamp and Paul Barth in 1931 for Rickenbacker, and was used in an aluminum guitar! It operated on a very simple principle, induction. Cutting through the finery, you take a magnet (or magnets) and wrap it thousands of times over with a thin copper wire. The strings of the guitar (made from a magnetic alloy) move and vibrate inside of the magnet’s field creating electric current in the wire at the same frequency as the vibrating strings. This signal is fed to your amp, and hey! Bob’s your uncle!

Field Diagram

Magnetic pickups have a near infinite variety! Lipstick tubes, soapbar P90s, dogear P90s, single coils, humbuckers, mini humbuckers, the list goes on. All have their own characteristic sounds that are influenced by the differences in their constructions, but they all fall into two categories. Single coils and humbuckers.

Lipstick TubeLipstick Tube Single Coil

Single Coils

A single coil pickup is not much different than the general description that I provided earlier. Most Fender style single coil pickups actually have six separate magnets, (1 under each string) where a P90 has 1 long magnet and a shorter bobbin. The bobbin is the piece of plastic around the magnet. A taller bobbin places the copper wire closer to the magnet, creating a brighter sound. Single coil pickups tend to provide a lower output than a humbucker, and a clearer, stronger representation of the higher frequencies. Since they are basically glorified antennae, they are highly susceptible to RF interference, especially 60Hz hum from fluorescent lights or electrical lines.

Strat SinglesFender Strat Single Coils

Humbuckers

The humbucker was invented by a scientist working for Gibson in 1956. His name was Seth Lover, and his creation first adorned Gibson’s 1957 line of guitars. He flipped the magnet in a pickup and wired it backwards to a normal single coil. The result was a reinforced signal with greatly reduced electrical interference! By wiring the pickups together backwards, he had two near-identical electrical signals (with interference) combining out of phase and canceling each other off. By flipping the magnet, he reversed the polarity of the induced current on the second pickup so that it was in phase with the first. Since the interference exists in the copper wire, not in the string’s vibration, his humbucker generated a strong signal without the noise.

Humbuckers tend to produce a very powerful, dark signal. With today’s demand for more powerful pickups, wax potting has become a common practice in humbucker design. The copper wire is covered in wax to reduce the microphonic qualities of the pickup, qualities that can easily lead to squeal and feedback if not controlled.

Patent
The patent filed by Seth Lover for the first humbucker

Make It Work For You

Because a pickup is a magnet, it can have an effect on the vibration of your strings. Many intonation problems, or the sudden loss of sustain can be solved by backing the pickups away from the strings. This is usually accomplished by turning two screws on either side of the pickup. Experiment a little bit here, there’s not much you can harm. See just how high you like your pickups. The closer you get to the strings, the stronger the signal will be. You will also notice the magnetic effect of the pickup on the strings more. Humbuckers can generally be positioned much closer to the strings than single coil pickups. If you have adjustable pole pieces, you can experiment even further. The most common practice is to adjust them to follow the heights of your strings, but you can custom tailor your sound this way. Remember, there’s a 1:6,900,000,000 chance that you aren’t Jimmy Page. The pickups are just a tool for your creativity, you have to find your sound.

Next week, I’d like to take a step away from both electronics and the history lesson, and bring you some great tips on how to get the most out of your bridge/saddles, and (if applicable) tailpiece! And if that wasn’t enough, you’ll get to see pics as I illustrate it all on my Les Paul.

Have something you’d like to add or explore further? This topic is open for discussion at the Studio Central forums:

Discussion

Further Reading:

Donald Brosnac’s Guitar Electronics for Musicians, ISBN:10 0711902321

One Response to “Magnetic Guitar Pickups, ‘How’d They Do That?’”

  1. [...] Magnetic Guitar Pickups 39 How 39 d They Do That 39 Blogosphere One Posted by root 17 hours ago (http://audio-pro-central.com) Jan 15 2007 i 39 d like to shed a little light onto their history with today demand for more powerful pickups wax potting has become a you must be logged in to post a comment blogosphere one is proudly powered by wordpress Discuss  |  Bury |  News | magnetic guitar pickups 39 how 39 d they do that 39 blogosphere one [...]

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