Teisco Gold Foil repair

fixing a vintage Gold Foil pickup

I bought this '60s made in Japan Gold Foil on eBay "as-is" with the intent to repair it.  It had no output and showed no resistance on the meter so I took the cover off by removing the phillips head screws on top.  

Next I removed the magnets which are simply held in place by their own magnetism on either side of the coil.  They were installed with South polarity facing up.  As I was inspecting the coil, I removed some tape and noticed the tiny 44 gauge coil wire had become detached from the white lead wire.  I resoldered and checked the resistance, it was now showing 5.3K.  

This might seem like a low resistance for a single coil, but don't be fooled!  The low resistance makes these nice and clear while the powerful magnets and the squatty coil make it sound full and fat.  I have repaired another Teisco Gold Foil that was around 6.3K and I have seen DeArmond pickups showing upwards of 10K, so there is quite a variance in specs of what is called a "Gold Foil".  I based my own Humbucker-size Gold Foil pickups on vintage pickups I see come into the shop.

When dealing with classic pickups like this, it is always better to use the original coil if possible for the most authentic tone.  The most common cause of dead pickups I see is sweat or moisture corroding the coils.  Usually there is no other way to repair a corroded coil than to rewind it, which I will do with vintage-spec wire to the appropriate number of turns.  Rewinds usually cost about $50 per coil. 

With this pickup I will probably wax pot it so that it will be less microphonic and install in a Telecaster.  Here is a quick video I made of the pickup in my tester guitar:

The Nashville workshop!

As some of you know, my girlfriend and I moved from San Francisco, CA to Nashville, TN in May 2015 to be closer to a vibrant music scene and to start a new life in The South.  The move was so exciting as we took a two week road trip across the country.  You don't get many chances to pick up and move to a new place so we took advantage of the opportunity.  Becca started a blog called the Bay To River Rambler and you can see her photos and writings here.

We found a place in East Nashville with a standalone garage that I converted into a workshop and now I have more space than I know what to do with!  I built myself a 2x8 workbench and got a drill press and now I am up and running.  The pickup winder is all tuned up and I'm cranking out pickups again, ready to get your guitar tone in tip-top shape.

Things to look forward to in July:

Gold Foil release July 4th I'll be releasing a brand new pickup based on the originals from the '60s.  I designed mine to be on the more affordable side compared to vintage or reissue pickups by other manufacturers and still embody that twangy, low-fi character.  They will fit in a standard humbucker rout and start at $90 each.




Summer NAMM in Nashville July 9th, 10th, 11th  I'll be there walking around, checking out the exhibits, and meeting as many people as possible.  I won't have a booth this year, but I'll be staking it out for future years.  Check out https://www.namm.org/summer/2015 for more info on how you can go.

Balancing output with a humbucker

Using a simple resistor to match a single coil with a humbucker

It's a classic combination: a humbucker in the neck and a single coil in the bridge, but it can be a real challenge to keep that single coil from sounding too thin in comparison.  The problem arises for three reasons:

1. humbuckers are naturally warmer and louder than single coils
2. at the neck the string vibrates farther than at the bridge causing more bass and volume
3. humbucker-equipped guitars usually come with 500K pots

The third reason is the one I'll be talking about first.  Typically humbuckers sound better with 500K pots and single coils sound better with 250K pots.  This is because single coils sound better with a little bit of the highs bled off to the ground, and humbuckers (being naturally dark) sound better wide open.  This Telecaster Custom (shown above) came with four 500K pots, one each for neck volume, neck tone, bridge volume and bridge tone.  This sounds fine for the humbucker but to give the bridge pickup a little more warmth we are going to use a resistor.  If you follow this link you'll find a wiring diagram for the American Telecaster HS.  Scroll down to the second page and you'll see two pots, a switch and a resistor leading from the hot lead of the bridge pickup to ground.  Scroll down to the third page and you'll see that these are 500K pots and a 270K resistor.  I didn't have a 270K resistor, so for the Telecaster Custom we are going to use a 220K in series with a 39K resistor to give us 259K.

I then covered the resistors with shrink tubing to prevent a short and soldered it between the ground and the first lug on the volume control where the hot lead for the bridge connects.  You can also see a high-pass filter soldered between the first and second lug of the volume control consisting of a .001 uF capacitor and a 150K resistor wired in parallel.

This gives you a more uniform blend of highs and lows when you turn down the volume control.  This trick works great on bridge and neck pickups and I use it on all of my guitars.

The final thing to do is adjust your pickup height.  You want your bridge pickup to be reasonably close to the strings without touching them.  Depress the first and sixth string at the last fret and raise the pickup until it is very close.  If the pickup sounds harsh and metallic then back off a touch.  The neck pickup should be adjusted all the way down to the pickguard and then raised until the volume of the two pickups is equal.

Wax Potting and Microphonics

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.

Pickup Magnetism

magnetizing a strat pickup with powerful rare-earth magnets

With all the talk out there about scatterwinding and coil wire types, it's easy to forget about how much of a role the magnets play on the sound of the pickup.  A lot of pickup manufacturers will charge the poles all the way up and be done with it giving little thought to "tuning" the magnets, but a few of the boutique builders out there will take the time to "hand weaken" the magnets.  

To charge up the poles, rare-earth mangets, like those used in guitar repair, are placed in the jaws of a vice.  One has it's north pole facing in and the other south.  The rare-earth magnets will charge the Alnico poles with the opposite charge, north charges south and south charges north.  This is because we all know that if you put two magnets with a south polarity in close proximity, they will repel or demagnetize each-other.  As the bobbin with the magnets is swiped between the rare-earth magnets, it is fully charged to about 35 gauss.

A fully-charged south-up Strat pickup

Now that the pole is charged all the way up, we can widen the jaws of the vice to about twice as far as they were before.  The pickup is flipped around so that it's south pole will be facing the south pole of the rare-earth magnets and north will be facing north.  With the jaws of the vice farther apart, we are just weakening the magnets a little bit, the closer we move the jaws of the vice, the more magnetism we are removing.  It only takes two or three swipes through through the jaws to weaken the poles a little bit.  In general, I weaken my neck pickups to less than 30 gauss and my bridge pickups to less than 20 gauss.

By weakening the magnets, we are essentially aging the pickups to sound like something 40 or 50 years old.

Setting pickup height

Depress the first and sixth strings at the last fret.  Now with a ruler measure from the bottom of the string to the top of the pole.  In general, bridge single coils should be about 1/8" away from the strings.  Humbuckers can be set a little closer.  The closer the pickup is to the string, the more bright or harsh the tone will be, the farther away it is the warmer the tone.  Once you get something you are happy with you can move on to the neck pickup.  Since the strings are vibrating farther over the neck pickup, this pickup will always be louder and warmer than the bridge pickup.  Lower the neck pickup towards the body until the volume is even with the bridge pickup.

It's really a matter of personal taste and there is no wrong way to set magnetism or pickup height, but if the pickup is too close to the string it will pull on it too hard, killing your sustain and messing with intonation.  If the pickup is too far away it will sound too dark and quiet.  

How do humbuckers work?

Humbuckers are great for their warm, powerful tone, and best of all they "buck" the hum that single coils are usually are prone to.  60-cycle hum comes from electronics that surround us every day like florescent lights and power transformers, and it sure doesn't sound very good when it comes through an electric guitar amp.  That's why humbuckers were such a valuable invention when music was getting louder in the 1950's, but how do they work?

Humbuckers are basically two single coils arranged side-by-side (fig. 1), each with six magnetic poles or slugs (one for each string).  They are wired in a way that cancels the unwanted frequency and keeps as many of the good frequencies as possible.

fig. 1

Most modern Stratocaster guitars (fig. 2) have a humbucking option built in.  The middle pickup is reverse-wound/reverse-polarity to the neck and bridge, so that when they are used in combination they will cancel any hum.  This only works because the two coils are so far apart and the harmonic frequencies are so different, the only quality that is the same about them is the hum, so when the two coils are opposite, they cancel the hum. 

fig. 2 the middle and bridge or middle and neck pickups are hum-canceling together

 Humbuckers function a little differently than this. Since the coils are so close together (as close as they can possibly be without being on top of each other), they are sensing very similar sounds and they need to be out of phase to cancel the hum.  Humbuckers consist of two coils (both wound counter-clockwise) with opposite magnetic poles facing up, usually wired in series.  

Some people don't like how humbuckers aren't as clear or bright as single coils, but what a lot of people don't realize is that there are many different ways of building humbuckers to change the tone.  The original Seth Lover PAF humbucker (which is the baseline against which all other humbuckers are judged) consists of 5000 uniform winds per coil (not scatterwound), bar magnets mounted underneath, adjustable poles on one side, slugs on the other, topped off with a nickel-silver cover.  All of this makes for a pretty dark sounding pickup.  Which might sound great in certain guitars, but some guitars beg for bright, twangy tones.  You could use scatterwound coils (for a brighter, clearer sound) and solid Alnico polepieces much like a Strat pickup.  This is the formula I used for my Apex Humbuckers.

fig. 3 my Apex Humbucker

You could also have an underwound humbucker (say with 4000 winds per coil) for a brighter tone, and you could wire these coils in parallel (instead of in series) for pickup with a clear tone and absolutely no hum.  

So there are lots of different options when it comes to getting different tones out of humbuckers, they don't always have to be dark sounding.  Most modern humbuckers come with 4 conductor leads so you can split the coils, and you can look up a wiring diagram here to experiment a bit.  Knowing your color codes of your pickup wires will be very helpful too, here is a link to color codes of a number of popular humbucker manufacturers.