Why Single Coil Pickups Produce Hum and Droning Sounds: Understanding the Physics and Solutions

Single coil pickups are a favorite among guitar enthusiasts, known for their rich, warm tones. However, they can also create a loud humming and droning sound, especially when not being played. This article will explore the physics behind the humming sound, ways to mitigate it, and the role of different pickup types.

Understanding the Hum

The primary reason single coil pickups produce hum is 60 Hz AC powerline interference. This interference is caused by the way the magnetic fields generated by the pickup interact with the alternating currents used in electrical systems. When a single coil pickup produces a signal, it is affected by the ambient 60 Hz magnetic field, resulting in a humming sound. This effect becomes more pronounced when using just one pickup, without the benefit of noise-cancelling from a humbucker#39;s dual-coil design.

Types of Single Coil Pickups

Single coil pickups come in various types and designs, each with its own characteristics:

Fender Pickups: Fender uses smaller single coil pickups, which are more susceptible to 60 Hz interference. This can be particularly noticeable when using just a single pickup. Stratocaster bridge pickups, in particular, have no tone control and require extensive filtering to eliminate noise. Engineers often use multiple filters and software processing to clean up the signal. P-90 Pickups: Used on Gibson and Epiphone hollowbody guitars, P-90 pickups have more windings and produce a milder, more mellow tone. They are less prone to hum and produce an excellent distorted sound, especially at high volumes. However, even P-90 pickups may still produce some hum in certain conditions, especially with high output settings or when using them in multiple pickup configurations.

Solutions to Hum and Droning Sounds

While single coil pickups inherently produce hum, there are several ways to mitigate or eliminate this unpleasant sound:

Using Filters and Pedals: Professional guitarists often carry a variety of effects pedals to filter out hum. Using a guitar with multiple pickup configurations or a 5-way selector switch can also help. For example, switching to position 2 or 4 on a Stratocaster or position 2 on a Telecaster can activate two single coils with opposite polarity, effectively acting as a humbucker and reducing hum. Using Noiseless Pickups: Modern noiseless single coil pickups, such as those from Fender, are specifically designed to reduce hum and still deliver a vintage Strat-like tone. These pickups use advanced noise cancellation techniques and are a popular choice for many guitarists. Proper Shielding and Grounding: Proper grounding and shielding of the guitar and amp can also help reduce hum. Ensuring that there are no loose connections or areas where the magnetic field can penetrate can significantly minimize the humming sound.

The Role of Frequency and Resonance

Single coil pickups are more susceptible to high-frequency resonances, which can exacerbate the humming sound. Humbuckers, on the other hand, have a dual-coil construction that cancels out these resonances and hum more effectively. This is because the two coils in a humbucker pick up the signal with opposite phase, effectively canceling the noise.

Conclusion

While single coil pickups are beloved for their distinctive tones, the hum and droning sounds they can produce are a common issue. By understanding the physics behind the hum, using appropriate solutions like filters and noiseless pickups, and taking steps like proper shielding and grounding, guitarists can significantly reduce this unwanted sound. With the right techniques and equipment, single coil pickups can deliver clean, high-quality sound without the annoying hum.