Electromagnetic voltage reduction

Discussion in 'General Electronics Chat' started by OptimumElectronics, Jun 16, 2013.

  1. OptimumElectronics

    Thread Starter New Member

    Jun 16, 2013
    Hi All

    In a guitar Humbucker, when the 2 single coils are connected, they cancel the HUM.

    If a humbucker is split so that one coil is used, to say, emulate a stratocaster single coil. It produces hum.

    Can you connect a 100K resistor to one coil and connect it in series with the other coil. This will reduce the voltage of one coil and will sound like a single coil?

    ||(Ground)||---[[[[[[]]]]]]-[series with100kΩ]---------[Series with other coil[[[[[[[]]]]]------>OUTPUT OR

    ||(Ground)||---[[[[[[]]]]]]-[ parallel with 100 Ω]---------[ series with other coil[[[[[[[]]]]]------>OUTPUT

    -[[[[[[[]]]]]]- is one coil of the humbucker.

    If this is not the way to go. How can you reduce hum from a single coil please?

    Thank you for your help :D
    Last edited: Jun 16, 2013
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    The single pickup should not 'hum', that is not a normal operation mode for a pickup coil. so....

    look for sources of noise near you. Florescent lights are one such source. Other AC power devices nearby should be powered off as well. Different AC circuits might also be tried to see if the noise is from something on the same circuit you are currently using. Go to friends house and see if the noise is still present there as well.

    Lifting the ground prong from your amps AC power cord is another way that sometimes works(three prong to two prong adapter required). This defeats some of the safety features and may expose the user to severe shock in wet conditions or if a fault is present in the amplifier power supply section.

    The resistor idea may work, it is a method I have never tried before, but someone else may be able to provide more info on that specifically.
  3. #12


    Nov 30, 2010
    A Humbucker is a brilliant solution to a nasty problem. I spent all day trying to get a single coil P-bass to quit picking up the fluorescent lights and I failed! I shielded the control cavity, I grounded the bridge, I grounded the person (guitar player), I checked and double checked every part, every wire, and every connection, and I failed.

    A Humbucker is 2 coils wound in opposition to each other. It would seem that they should produce nothing as an output, but they don't. It's because of the difference between near field excitation and far away energy radiation. Any energy coming from a relatively long distance affects both coils almost exactly the same, and thus the output voltage of the 2 coils (almost perfectly) cancel each other. The strings, being a near field energy, will produce slightly different results in each coil, and that gets amplified by the amplifier.

    We do the same with 2 identical microphones wired in opposition. Tape them together and put them on a mic stand, and the audience noise almost disappears. The performer, being within inches of the mics, produces a slightly different voltage from each mic and that gets amplified. Both signals, the far field energy and the near field energy, get diminished quite a lot, but the signal to noise ratio improves dramatically.

    When it comes to delivering music, signal to noise ratio is immensely important.
    As for, "How can you reduce hum from a single coil?" the answers are numerous because none of them are perfect. Just to name a few,

    Shield everything, and do it without creating ground loops that pick up current by means of induction.

    Play in a building that has no electrical wiring.

    Don't use any high energy discharge lighting like fluorescent or metal halide.

    Shield every part of the single coil pickup except the screw heads that pick up the string movement.

    Build a Faraday Cage and stand inside it to play the guitar.

    Attach another pickup coil to the guitar and wire it like a humbucker, except it isn't right under the strings.

    You are free to experiment all you want. I hope I have laid down some information that will guide you into knowing why some of your experimental methods don't work well. The bottom line is that there is no reasonable substitute for Humbuckers. They were invented because they do an important job, and they do it well.

    That said, I rarely work on guitars. Somebody else might have found a solution that I haven't found, simply because they have a lot more experience. I hope one of them answers you here.
    GopherT likes this.
  4. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    You can buy single coil sized pickups in humbucker configuration;



    Also some single coil pickups are much better shielded than others. Just adding foil shields around the coil can make a lot of difference. If you are using just one coil from a humbucker the humbucker was likely to have no shielding.

    You could google for "shielding a humbucker for single coil use" or something like that. :)
  5. kubeek


    Sep 20, 2005
    From my experience, the only thing that lowers the mains noise being picked up with singles is to rotate yourself until you find the angle at which the noise is lowest. Sadly this doesn´t really work well when performing on a stage, so applicable only for recording.

    Connecting two singles together will cancel the noise only if they get it at the same level, and of course it will change the sound. But if I am not mistaken there should exist single pickups that have a second "dummy" coil that provides the noise cancellation while retaining the sound of a single pickup.
  6. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    Those humbucking singles in my post above do that, at least they do cancel the hum and come very close to the clarity of a single coil pickup sound.

    It's fairly new technology that companies have spent a lot of time and effort on, to try to get humbucking benefits but keep the single coil size and sound.