Things to Know About Pickup Replacement - Part 4

Hello.
A junior colleague told me, “It’s unbelievable that you don’t know Adventures of Gamba,” and passionately explained the story to me, so I ended up watching all 26 episodes.
The ending song, “The Ballad of the Adventurer”, is excellent, but it’s quite bold for a children’s anime. I highly recommend giving it a listen.
By the way, my favorite character is Ikasama.

In the previous post, I wrote about the structure of pickups and the factors that affect their sound.

⇒ Things to Know About Pickup Replacement - Part 3

I thought I could move on to the next chapter, but I realized I forgot something important:
The structure of the humbucking pickup, commonly known as the humbucker.
It is generally said that humbuckers are less noisy and have higher output than single coils, but why is that?
I’d like to explain the mechanism behind it.

○ The Birth of the Humbucker

First, a bit of history on how the humbucker came to be.

When it comes to guitars equipped with humbuckers, the signature model with the world’s highest recognition, Gibson’s Les Paul, comes to mind.
However, the pickups on the early Les Paul models were not humbuckers but single coils.
These were the P-90s, developed by Walter Fuller.
They were excellent pickups with a unique warm tone and adjustable poles, but as music evolved over time and guitarists preferred distorted sounds at high volumes, a problem emerged.
It’s noise.
Despite various countermeasures, single coils had their limits.

In 1955, Gibson’s president at the time, Ted McCarty, called upon Walter Fuller and Seth Lover to develop a new pickup with a less noisy structure.
Thus, the world’s most famous humbucker, the PAF, was born.

The name PAF comes from the PAF sticker on the back of the pickup at the time, but it stands for “Patent Applied For”, indicating that the design was pending a patent.
This was a groundbreaking invention back then, and the sticker served as a warning to others not to disassemble and copy it.
Well, nowadays, many manufacturers sell pickups replicating the PAF.

After Gibson conquered the electric guitar market with the humbucker, their biggest rival, Fender, couldn’t stand by idly.
Although Fender also worked on developing humbuckers after Gibson released theirs, they couldn’t complete the task.
In 1967, Fender took a bold step and recruited Seth Lover.
Oh, come on, seriously, that’s a bit much, isn’t it?

This led to the creation of Fender’s first humbucking pickup, the Wide Range Humbucker.
Known for its unique appearance and well balanced powerful tone, it still has many fans today.
This pickup, formally named the CuNiFe Wide Range Humbucker, gets its name from the magnet used.
The magnet is composed mainly of Copper (Cu), Nickel (Ni), and Iron (Fe), and these materials are also used in lead wires for light bulbs and vacuum tubes.

Thus, humbucking pickups have continued to evolve with the changes in music.

○ Structure of a Humbucker

Now, onto the main topic: the structure of a humbucker.

A humbucker is made by combining (connecting in series) two coils, essentially merging two single coils as in the image above.
What happens then?
This results in twice the power.
However, it also means twice the noise, as both coils detect noise similarly.
So, how can this be addressed?
By reversing the winding direction of the enamel wire on one of the pickup’s coils.

This reverses the current direction in one of the coils.
So what happens? By reversing the winding direction of the two coils, the noise signal is reversed.
This is called the reverse phase. By making the noise signals out of phase, they cancel each other out, reducing noise.
However, reversing the coil winding direction also reverses the output phase of the pickup, causing the plucked sound to cancel out.
To fix this, the magnetic polarity of one coil is also reversed.

This reverses the magnetic field direction, restoring the output phase.
While it might seem that the noise phase would also reverse, increasing noise, the noise phase remains unaffected by the magnetic field.
The result is that the noise is in the reverse phase and the output signal from the pickup is aligned in the same phase.
So now the noise is canceled out in reverse phase and the output of the pickup is in phase and connected in series, so a powerful pickup that is resistant to noise is completed.
Although theoretically noise-free, practical applications show it is merely noise-resistant, not noise-free.

Why can’t noise be completely canceled?
The positions of the two single-coil pickups forming the humbucker are not identical.
If they were in the same position, their noise signals would be identical, and out-of-phase cancellation would eliminate the noise. However, the humbucker’s coils are arranged side by side.
This would pick up sound and noise in different positions and the shapes of the signals are slightly different from each other, so the noise cannot be completely canceled out.
The same principle applies to the out-of-phase selector switch on a Mustang, which results in a thin, incomplete sound.

How was it ? I’m sorry that the historical background became so long.
You may have gotten a little confused reading all the things, but I hope this explanation clarifies the structure of the humbucker for you.
There are still many aspects of pickups I would like to discuss, so I plan to continue writing about them from an engineer’s perspective in future posts.

See you again on the Sound House Staff Blog.
Goodbye.