How things work for guitars

By Joshua Adams | Staff Writer

Electric guitars are used in just about all types of music. While most guitarists are fluent in the language of music and technique, many may not be well acquainted with the knowledge of how the electronics inside of the electric guitar work.

The inner workings of an electric guitar are actually quite simple, and there’s a lot of room for preference when it comes to deciding on the sound a guitarist may want.

Berkshire Guitars, located on the corner of 13th and Reynolds Streets, is run by father and son, Ron and A.J. Berkshire. Berkshire Guitars has been building, repairing and customizing instruments for about nine years and are well aware of how the electronics of a guitar work.

“If you’ve got a guitar, bass, violin, cello, banjo or ukulele, we can work on it,” luthier A.J. Berkshire said.

When it comes to electric guitars, Berkshire said, there are three different types of pickups: single coil, humbucker and P90.

“There’s a lot of nuances to electronics, but the primary difference you run into falls mostly on the single coil and humbucker,” Berkshire said. “The difference is that the single coil will almost always have what is called the 60-cycle hum, which is essentially the pickup’s natural magnetic field picking up noises from the room. The humbucker was invented by Seth Lover, and he realized if you run two of these coils in series with each other, directly next to each other, it cancels out the hum and makes a very quiet but responsive pickup. The P90 is kind of like the father of all pickups, as it was around before the standard single coil. It’s similar to the standard single coil, but it’s larger. In general, P90s are known for their warmth and midrange. They tend to be used in jazz or classic rock.”

Berkshire said there are many misconceptions of how pickups actually work.

“One of the common misconceptions is that a lot of people call them electromagnetic, but they’re actually electromechanical because you’re not putting electricity into the pickup to make noise, it’s actually picking up differences of magnetic fields and transforming that electricity,” Berkshire said. “The way that works is that you have slugs running down the middle of the pickup, or pole pieces, and those are magnets. Usually, in a single coil, they’re individual magnets, whereas in a humbucker, there is a metal pole piece that has a magnet underneath it that makes a magnetic field. The magnets are wrapped with wire, usually copper, and that creates a very sensitive electromechanical sensor.”

Between the strings and pickups, an electromagnetic field is created, Berkshire said, and when it’s disrupted, electrons move about within the wound copper and creates an electric signal. From there, the signal goes from the pickups to pots.

“Most potentiometers, or pots, are usually 250K or 500K,” Berkshire said. “Think of the size of your door. If you have a standard doorway to your house, it lets in people-sized objects. When it comes to frequency, for example single coils, it tends to let through a little less noise. A 500K pot is more like a garage door, where it lets through everything. It’s typically to amplify the high frequency from the humbucker pickups.”

Volume pots control the overall sound, but tone pots have a capacitor added to them to control high frequency noise.

After the pots, the signal travels to the input jack, where the guitar is then plugged into an amplifier, Berkshire said. This completes the hot line of the in series circuit. The ground line comes off of the pickup and is attached to the guitar, usually at the bridge.

“The ground wire goes to the bridge of the electric guitar,” Berkshire said. “It’s really important because in front of the pickups are the metallic strings. When they’re vibrating inside that magnetic field, static can build up in the strings. If the bridge isn’t a grounded part of the system, it can arch between them and cause a shock, which depending on size of amplifier can cause death.”

Matt Poppell, local guitarist and apprentice electrician, has gained a great deal of knowledge of how guitar electronics and tone works in his 13 years of playing. His interest in guitar electronics led to him choosing a career in electrical work.

“I used to be a real big nerd when I was little,” Poppell said. “I would play with Legos and build things. I progressed from building things with Legos to building things with scrap wood that I would take from my dad’s contracting business. When I got into music and started playing electric guitar, I got real into creating specific tone. So naturally, I started researching and looking into that, which led to [understanding] how vacuum tube amplifiers work and how pickups work in an electric guitar. Eventually I realized college wasn’t going to work out financially for me, and I came back home and began looking for an occupation that would pay the bills.”

Aside from his knowledge of how pickups and internal electronics work inside a guitar, he says that tone is also heavily dependent on the amplifier a guitarist chooses. Amplifiers take the electronic signal created by pickups and converts it back into a soundwave. Poppell said he prefers to use humbuckers ran through vacuum tube amplifiers over solid state amplifiers.

“A tube amplifier utilizes the heating of vacuum tubes, like from old TVs,” he said. “You’ve got two stages in an amplifier: a preamp section and a power amp section. Preamp tubes are generally smaller. Typically they’re called 12AX7. Power tubes are a little bit bigger. Essentially, you get your tone from the preamp tubes and your power from the power tubes. The power tubes, however, also play a big part in the tone.”

EL-34s are British power tubes, whereas, 6l6s are more of an American power tube, Poppell said.

“I love America, but I cannot make those tubes sound good at all,” he said. “EL-34s tend to have more mid-range [frequencies] breakup earlier on in the volume scale. 6l6s have a lot more headroom, which sounds cleaner until you get into higher volumes.”

In between the electrical signal’s run from guitar to amp, guitarists can be seen “tap dancing” with their pedal board on stage, Poppell said. Pedal boards are composed of individual circuits, either capacitors or resistors, which modulate the electrical signal. Poppell said the various effects a guitarist chooses is entirely dependent upon personal preference.

Poppell said he used to use several effects pedals, but found them to be distracting. He said he has realized that less is more and has decided to trim the fat.

“On my pedal board, I have an overdrive, which is a distorted, rock’n’roll type effect,” he said. “I use that on top of the vacuum tubes to create a happy medium. I run that first overdrive into a second overdrive, just to get real crazy sometimes. From there, I run it into a spring reverb pedal, which is really wet sounding. It’s a useful tool for spacey sounding leads or playing real pretty music. I run that into a volume pedal for convenience on stage.”

Contact Joshua Adams at: jadams35@gru.edu.

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