Single Coil - Noise Problems

Noise Problems

It is important to understand that there are two types of noise that afflict magnetic guitar pickups, hum and buzz. Hum is directly attributed to magnetic disturbances in the ether caused by 50Hz or 60Hz alternating mains from electrical equipment, whereas buzz is propagated as Radio transmissions and sounds more like static. Simply put, the sources of buzz are many but one example is an AC power tool with a brush motor. The Brush (electric) makes and breaks electrical contact with the commutator segment several thousand times a second at variable frequency dependent on load thus causing Radio noise propagation.

Hum can be canceled by suitable arrangements of two coils within the pickup's architecture. Hum can not be screened out by conductive shielding. Buzz can not be canceled, it can only be dealt with by conductive shielding installed in the wiring cavities of guitars and must be grounded.

Fender Stratocaster and Telecaster pickups as well as Gibson's P-90 pickup being of the single-coil type, output a type of noise known as mains hum or 50Hz / 60Hz hum. Mains hum has its origin in wiring of a building and electrical apparatus/appliances such as transformers, electric motors and lighting. Hum is undesirable because it pollutes the musical notes being played on the instrument with its own sound of fixed unchanging frequency or pitch (usually 50 or 60 hertz) which is discordant with the musical sounds. To address this undesirable situation various attempts to eliminate mains hum signal from Fender single-coil pickups were made dating back to the early 1970s. DiMarzio, Seymour Duncan and EMG manufacture what are commonly known as stacks, or stacked single coils which cancel mains hum. Unfortunately the design is flawed and these stacks also cancel string signal due to magnetic coupling of the two coils which has a detrimental effect on sound quality. EMG used active circuitry within the pickup to compensate for the losses caused by stacked coils by boosting and reshaping the damaged sound but this required an on-board battery with its attendant inconvenience. The resultant sound is not authentic Fender trade mark sound but EMG pickups became popular for their own sound.

Actodyne General manufactured a low-noise design of single-coil pickup known as Lace Sensors, Don Lace being the inventor. The Lace Sensor pickup had a rubberized particle magnet and used ferrous shielding to reduce hum. Being the best at the time, Fender installed Lace Sensors on the Strat Plus model for many years as a solution to the mains hum problem. However the Lace Sensor was a stopgap solution because the sound was not authentic Fender trademark sound. Fender purists wanted the genuine sound of the original Fender pickups with Alnico rod magnets and Fender eventually discontinued Lace Sensors as their mainstay solution to mains hum circa 1998. Lace Sensors continue to be used by many guitar players regardless.

Kinman Guitar Electrix were awarded 5 or more US patents beginning circa 1996 for innovative design concerned with hum canceling single pole pickups. Kinman at first concentrated on particularly the Fender type single coil pickup and in 2009 the P-90 pickup. One of the most important elements of Kinman's patents is the use of iron in the core of the noise sensing coil. This was absolutely novel in 1996 and without the presence of iron to boost the efficiency of the noise sensing coil differential coil technology would not have been possible. Vertical differential coil technique is also described in Kinman's US Patents 5,668,520 and 6,103,966 with priority date of March 1996. After 1998 DiMarzio and Seymour Duncan also began using iron and differential winding techniques in the noise sensing coils in some of their products. Over the years Kinman has improved and refined their designs to a point where the popular consensus is the sound of some models is indistinguishable from noisy single coils. Kinman also manufactures noiseless P-90 and Telecaster pickups under US Patent 7,022,909

The search for an acceptable solution to mains hum gained new impetus around 1995 as guitar players became increasingly intolerant of degraded stacked single-coil sound. Fender was researching new techniques to solve the loss of tone around that time and eventually came out with their Vintage Noiseless design circa 1998.