Matador
Well-known member
I've been thinking, after helping someone battle noise in his Fender Strat single-coil setup. It was humming like mad, and after the traditional shielding job it improved - probably about as good as can be had from such a setup.
It seems to me that the inherent flaw in the setup is that essentially the pickup is converted to an unbalanced source as it enters the body of the guitar since we're referencing all internal voltages to one side of the coil (aka. 'grounding' one side of the coil). Hence any pickup of electrical noise will always be at full reference to this internal node, and there's no way to cancel it, only reduce it in magnitude. No amount of clever shielding will work, since the pickup coil will essentially always be exposed to the outside world.
So here enters the humbucking pickup, with its two opposite magnet orientations, and two coils that have opposite current flow, hence any common mode AC signal placed across both windings will cancel out, however the magnetic induction (via the vibrating guitar strings) will add together (assuming series wiring). However these don't sound the same.
Is there any way to get a regular single coil pickup to be hum free without resorting to splitting the coils and converting them to some form of humbucking configuration that changes the sound?
It seems to me we could center-tap a regular single coil pickup, without changing the winding orientation of the coil (which is how almost all 'single coil but noiseless' pickup designs work). Hence we would wind our single coil pickup no differently than before, with the exception that halfway through we would place a center-tap, then complete the wind. The center tap would become the new reference point, just like would be done in a full-wave rectification setup, so the coil would spit out a differential AC signal, with each end of the coil 180 degrees opposite in phase to the center point, just like in a full wave rectified power transformer.
The tone / volume controls would be placed just like before, across the coil(s), however exiting the guitar would be essentially a differential signal, plus a ground, just like the coil of a dynamic microphone, although of much higher output impedance. This could be wired into a a regular stereo jack and all that would be needed is a pedal that converts the differential input into a single-ended low impedance output. Or, the input to the amp could be designed to do this natively. In order to keep the common mode input range of the pickup tracking with the receiver, the shield of the cable can be tied to the pickups common mode center tap point.
By my reasoning, this setup should be common mode noise cancelling, like a humbucker, however the tone of the pickup shouldn't be impacted like it is with all of the other humbucking configurations. And no other internal shielding of the guitar or the wiring should be needed either.
Thoughts? I'm certainly not the first person who has thought about this, but I haven't seen this discussed previously on GroupDIY.
It seems to me that the inherent flaw in the setup is that essentially the pickup is converted to an unbalanced source as it enters the body of the guitar since we're referencing all internal voltages to one side of the coil (aka. 'grounding' one side of the coil). Hence any pickup of electrical noise will always be at full reference to this internal node, and there's no way to cancel it, only reduce it in magnitude. No amount of clever shielding will work, since the pickup coil will essentially always be exposed to the outside world.
So here enters the humbucking pickup, with its two opposite magnet orientations, and two coils that have opposite current flow, hence any common mode AC signal placed across both windings will cancel out, however the magnetic induction (via the vibrating guitar strings) will add together (assuming series wiring). However these don't sound the same.
Is there any way to get a regular single coil pickup to be hum free without resorting to splitting the coils and converting them to some form of humbucking configuration that changes the sound?
It seems to me we could center-tap a regular single coil pickup, without changing the winding orientation of the coil (which is how almost all 'single coil but noiseless' pickup designs work). Hence we would wind our single coil pickup no differently than before, with the exception that halfway through we would place a center-tap, then complete the wind. The center tap would become the new reference point, just like would be done in a full-wave rectification setup, so the coil would spit out a differential AC signal, with each end of the coil 180 degrees opposite in phase to the center point, just like in a full wave rectified power transformer.
The tone / volume controls would be placed just like before, across the coil(s), however exiting the guitar would be essentially a differential signal, plus a ground, just like the coil of a dynamic microphone, although of much higher output impedance. This could be wired into a a regular stereo jack and all that would be needed is a pedal that converts the differential input into a single-ended low impedance output. Or, the input to the amp could be designed to do this natively. In order to keep the common mode input range of the pickup tracking with the receiver, the shield of the cable can be tied to the pickups common mode center tap point.
By my reasoning, this setup should be common mode noise cancelling, like a humbucker, however the tone of the pickup shouldn't be impacted like it is with all of the other humbucking configurations. And no other internal shielding of the guitar or the wiring should be needed either.
Thoughts? I'm certainly not the first person who has thought about this, but I haven't seen this discussed previously on GroupDIY.
Lower inductance windings are a possible alternative route to the Humbucking configuration (which gives rise to frequency cancellation issues - fine if that's what you want - PAF / P90 et al but not so good for the classic Strat' tones).
