There’s been lots of interesting developments in electric pickups in the last 5-10 years. Many have tried to improve on tone, frequency response and noise. Zexcoil pickups have some very interesting ideas which focus on reducing noise found in single-coil pickups without giving up output or tonal character of traditional pickups.
The methods behind reducing noise in single-coil pickups are really three-fold:
- Reduce the effect of the outside interference by shielding and other methods (reducing magnetic fields which affect the pickups)
- Try and cancel the external effects using dummy coils
- Try and cancel the external effects within the pickups themselves
Number 1 is an obvious method for noise reduction, and anybody who wants to reduce noise should have their electronic and pickup cavities completely shielded for best response.
Number 2 is what’s usually implemented by a variety of makers by adding an additional backplate or some other component which is essentially a dummy coil which picks up the interference and adds it back in reverse polarity to what is picked up in the pickups, thus subtracting out the noise — but not completely. It also adds a load which tends to attenuate the output and response.
Number 3 is the method used in humbucker pickups. The idea is to have two different coils sense both the signal from the string as well as external noise. But have the external noise sensed in such a way that it’s opposite for both sensors so when they are added together, the noise cancels out. The way this is done in humbuckers is to have two single-coil pickups in serial, but one pickup (call it #2) is reverse wound and with reverse polarity in magnetic fields for the pole pieces. When the string vibrates, it interrupts the magnetic fields for both coils. In coil 1, a signal is produced. In coil #2, if the coil is reverse wound only, the signal would cancel — however, the magnetic field is also reversed, so the signals add. This is the key. For the external magnetic field noise, it affects the magnetic fields the same (regardless of polarity), so the reverse windings cancel out this noise.
Zexcoil take this idea for single-coils by having coils for each pole piece, and choosing specific coils to have one polarity and winding, with others the opposite. The idea to cancel the noise is the same as in humbuckers, but now the coils are distributed between strings rather than duplicated in a separate single-coil pickup (like in a humbucker).
Scott Lawing (the founder) is also an MIT Ph.D, so he’s done quite a bit of extensive analysis to understand the tonal properties of conventional pickups and try and duplicate them using this new technology.
Kudos to him for applying science and engineering to solve an old problem in a different way.
For more technical info on how this is all done, see this video: