Showing posts with label bucking the hum. Show all posts
Showing posts with label bucking the hum. Show all posts

Monday, October 20, 2014

Splitting humbucker coils

Humbuckers are essentially two single coils, side-by-side, wired in series (out of phase to "buck" the hum).  One cool feature is that you can split the coils and use them as true single coils to get a brighter, cleaner sound.  I say "split" the coils instead of "tap" the coils because that is something different entirely that gets confused often.  Coil "tapping" is having multiple leads going to the same coil to access different output values.  In order to "split" your coils, you must have four leads (five, including the bare ground wire).  Here are some common humbucker color codes:



By connecting the South finish (-) and North finish (+) you have both coils wired in series with South start (-) connected to ground and North start (+) connected to the volume lug or the switch.  The wiring diagram below shows how to wire my Apex Humbuckers to a switch like a push/pull potentiometer to switch between "single coil mode" and "humbucker mode".  You will notice that my color codes are the same as Lawrence and Gibson.


If you look at the Tele wiring diagram above you will see that when the tone control is pulled up the lower lugs are engaged and the finishes for the bridge pickup become the "hot" lead.  Ground stays at ground, that means the bridge South coil is engaged.  Simultaneously, the right side lugs connect the finishes for the neck pickup to ground, making them the negative lead.  Hot stays hot and you have the neck North coil engaged.  When the neck North and the Bridge south are used together (the middle switch position) they are hum-canceling because they are reverse polarity, wired in parallel, out of phase.  

On most humbuckers, the coil with the adjustable poles is South-up, you can check by using a compass.  The North needle will be attracted to the South-up pole and South will be attracted to North.  My Apex Humbuckers do not have adjustable poles, but North-up and South-up coils are labeled on the bottom or you can use a compass to check.  

You can have a lot of fun getting some different sounds out of your instrument just by wiring it differently.  One of my favorite websites for wiring diagrams is www.guitarelectronics.com.

Monday, December 30, 2013

Canceling Tele hum on the cheap

For more than 50 years, the Fender Telecaster has been manufactured pretty much the same way. It's trademark sound is one of raw, gutsy tone with sharp attack and great clarity. Because of it's simplicity and honesty, it is perhaps the best way to showcase a pair of single coil pickups. One of the drawbacks of true single coils is their hum which guitar makers have been trying to fix for decades. Since the Telecaster's design was perfected rather early on in electric guitar history (1950) it is one of the only dual pickup guitars that did not have hum-canceling capabilities, and it still doesn't today. Most of the time the two pickups are made reverse-wound/reverse-polarity so that when they are used in combination (the middle position of your pickup selector) they will cancel the hum. The telecaster design has been pretty much left alone because so many players love the trademark sound and especially the sound you get when the neck and bridge pickup are played together. For a lot of players that is more important than "bucking" the hum, but for you it might be more important to have a quiet setting on the guitar. Here I will show you how to cheaply and easily buck the hum on a standard Telecaster. 

As we just discussed, most Tele pickups are wound the same direction and charged with the same polarity facing up, making them non-humbucking, so all you need to do is switch the leads and reverse the polarity on one pickup. You can test the polarity by holding a compass up to the top of the pickup as shown below. Opposites attract, so this pickup is charged SOUTH UP (fig. 1).

fig. 1

Reversing the leads on a pickup is a simple operation with a soldering iron, but charging the magnets will be a little more tricky.  Especially since most vintage, and vintage-reissue Telecasters have a copper-plated steel baseplate on the bridge and a chrome cover on the neck pickup, which is soldered to the ground of the guitar.  

Modern American Standard bridge pickups, like the one shown below, do not have a baseplate, and are changed NORTH UP (fig. 2), so here I will remove the pickup and charge it SOUTH UP.

fig. 2

This can be done with a pair of 1" rare earth magnets from Steward-Macdonald ($8.57 each).  These are extremely strong magnets that will successfully charge Alnico polepieces like in my pickups here.  They will also successfully erase hard drives like in you iPhone or MacBook, so keep them away from all computerized equipment.  You can see the magnetic field you are dealing with by holding it to a compass .  It is attracting the NORTH needle, so this is the SOUTH pole of the magnet (fig. 3).

fig. 3

Charge the pickup polepieces by moving them back and fourth between the rare earth magnets.  The magnets will change magnetic fields of weaker magnets to what they are most attracted to, so a SOUTH pole with charge pickup polepieces to be NORTH.  Rare earth magnets will hold themselves to the jaws of a vice.  Label the side that will charge magnets to be North as I have done below (fig. 4).

fig. 4

Adjust the jaws so that the magnets are as close as possible to the polepieces but still allow the pickup to pass freely.  Move the pickup through the jaws of the vice a few times and it is fully charged.  Reinstall the pickup with the leads reversed.  Positive leads are usually white or yellow and in this case would be soldered to the ground (the back of the potentiometer), negative leads are usually black, blue or green and in this case would be soldered to your switch.  

If this pickup had a metal baseplate (fig.5) or a cover it would be a little more difficult to charge the magnets but sill possible.  It would require disconnecting the negative (ground) lead from the baseplate or cover and running a separate ground wire from the baseplate to the back of the potentiometer.  Then, special care must be taken to break the hold of the potting wax and remove the baseplate or cover without damaging the coil.  Then you can charge the magnets.  

fig. 5

Now you have a hum-canceling mode on your Tele without effecting the tone of the bridge or the neck pickup!