Our resident expert Stew, the quieter version, is at it again, sharing his knowledge on humcancelling pickups.
For anyone who plays electro instruments, hum is a consideration, but luckily there are a lot of ways to cancel it. But like everything else in the world of instrument building, there are benefits and drawbacks to each approach. This will give you a quick overview of each. Just remember there are always exceptions to every rule, so little is absolute.
As a single coil is pretty much the building block for everything we do, the first way to kill hum is by splitting a coil. Thus the NJ4 becomes the NJ4SV (or NJ4SE), the NJ5 becomes the NJ5S (the ’S’ is actually for split coil), the Big Single becomes the Big Split, etc… One of the most popular pickups in the world, the Precision, is actually a split coil. Remember that the original Precision bass was styled after the Telecaster guitar and its one pickup was a single coil. The instrument we know now and its sound has come a long way from its humble origins!
The benefit of the split coil design is that it doesn’t take up much space, so a J pickup can still be made to fit in a J cover. The downside is that this generally produces a darker sound and does not create the same complexity, most specifically through the midrange, as a single coil. This will give the impression that the pickup has a more bass heavy signature, but this is really an illusion because the decreased midrange content also serves to emphasize the low end to our ears and brains. (NP4, NJ4SV
TWIN & QUAD COIL
The next way to defeat hum is with a twin coil design. This uses a pair of coils side by side, like a set of J coils in one cover. Both our Dual Coil and BigRig model fall under this umbrella, but so does the MM pickup. Where the first two models use a taller coil structure and a fair amount of wire on each coil, the MM has short underwound coils with huge magnets to get its signature sound, a part of the design as Leo Fender’s plan was to make the Stingray bass the world’s first active production instrument and the preamp he designed interacted so wonderfully with the pickup.
This method of hum canceling gives you the option of running the coils in parallel, series or singling out one coil, so you have a wide array of tones. This type of design requires substantially more work to build, which can raise the cost. Using a twin coil approach can also increase the weight of the pickup. Things get even more complicated because it’s often possible to split each of the coils and turn the pickup into a quad coil, like our MM5.4. This approach will make the pickup hum canceling in single coil operation but will also require even more work to make properly than a twin coil, which is reflected in its price.
STACK COIL & SIDEWINDER
The next way we choose to cancel hum is with a stacked coil, as we do in the Fat Stack. This method actually uses one coil sitting on top of another and uses the same magnets for both. This is a more challenging way to make pickups and has the unusual characteristic of the hum coil mode producing less output than single coil operation. The upside is that all that extra magnet load ironically contributes to a stellar single coil tone.
A variation of this is the sidewinder construction method, which is what we use in the Zen Blade. Rather than employing one coil atop another, the structure is laid on its side. In the case of the Zen Blade this means that there is not the typical difference in output between series and parallel operation.
While it is far less common, occasionally someone will utilize a triple coil design. Ernie Ball and Ibanez have both employed them in the past. Aside from the complicated build process, trying to figure out the wiring for a triple coil pickup can be maddening. Additionally, it will require an unusual (deep) pickup cavity and with more and more builders using slim bodies, a triple coil pickup may not be the best choice. These are some of the reasons why triple coils are seldom seen.
As far as creating sets of pickups using different types of hum canceling pickups, or combining single coils with hum canceling designs, this can be done but the explanation would turn this into a small book rather than a short article.
While this is the extent of what we do here at Nordstrand right now, there are other ways to cancel hum. Rest assured that we will continue to explore this in both our bass and guitar pickup lines, so if you have any questions at all about this, please contact us at the shop and we’re happy to discuss what will work best in your situation. And remember a set of single coils is hum canceling as long as both pickups are wide open!