326. What is under the white or black Fender Strat covers?
The covers are used to protect the coil and bobbin from damage due to picking, string snag and other elements that could break the coil. Under the covers are the bobbin assembly which consists of:
- 6 Alnico magnets sand cast and ground to desired diameter and cut to length.
- Top flatwork- made of Vulcanized Fibre or chemically compressed paper in black.
- Bottom flatwork- made of Vulcanized Fibre or chemically compressed paper in black and various shades of gray.
- Two eyelet’s for attaching the beginning and finish of the coil, a coil wound from many turns of 42 Formvar insulated magnet wire (older bobbins) and 42 Plain Enamel (newer bobbins)
- The pickups are connected to the controls by two 22 gauge stranded hookup wires.
Pickups are very fragile and extreme care should be done when removing or putting covers on. The cover can snag and break the fine magnet wire causing the pickup to fail. Newer covers are made from a pliable molded nylon that can withstand lot’s of picking without fatigue. Earlier plastics used for Stratocaster covers would crack and chip and after early production nylon was substituted for endurance.

327. What kind of pickups are used on Fender pedal steels?
The early Fender 1000 (Double neck) and Fender 400 (Single neck) pedal steel guitars used 8 pole pickups similar to Jazzmaster guitar pickups. The early pedal steel pickups used 8 cylindrical rod magnets that were flush with the top of the molded cover and staggered below for the various strings. Each neck used a single pickup that was perpendicular to the strings. Each coil used 42 gauge plain enamel wound to the desired number of turns. The top and bottom flatwork on the bobbins used a .093” thick black Vulcanized fibre. The bottom of the magnets are ground for easy bobbin assembly. In the 63-64 Fender catalog it shows a new pickup design very similar to the Fender Jaguar pickup. The bobbin was wound with 42 gauge magnet wire and each pickup had a notched claw around the pickup to keep the magnetic field in closer proximity to the coil for better highs and slightly more output. The cover was molded in black nylon for picking endurance.

328. What kind of pickups are used on older Fender Lap Steels?
There were several types of pickups used on K & F and Fender lap steels. In Leo’s and “Doc” Kauffman’s early patent number 2,455,575 filed on September 26, 1944 and granted on December 7, 1948 there are several components. The bobbin consisted of a Vulcanized bobbin with 6 tubes in which the strings would go through without touching the walls of the cylinders. The pickup used two Alnico bar magnets and held in place by two fabricated case hardened steel shells and the bottom shell or case would support the string and guide it through the cylindrical tubes. The case hardening keeps the string from cutting into the edge of the material. The strings were actually through the center of the coil. The pickups looked rectangular from the top. The front side of the shells or casing are notched between each string to focus the magnet field to the strings. Each end of the pickup uses a sand cast Alnico magnet with the same polarity facing up on each end. Below are some winding specs for a few “Direct String Pickups” where the strings go through the pickup.
Fender Lap Steels that I’ve evaluated:

Lap Steel Model Turns Magnet Wire Shape
K & F Lap Steels 7,522 Turns 42 PE rectangular pickup
Organ Button Model 7,954 Turns 42 PE rectangular pickup
Deluxe Model 7,633 Turns 42 PE rectangular pickup
Dual Professional 7,855 Turns 42 PE rectangular pickup
Custom Triple Neck 8,319 Turns 42 PE Offset rectangular pickup

The Direct String Pickups use two Vulcanized fibre flatwork and often a clear vinyl plastic, computer cards or thin fibre board was used for the center of the bobbin. Spacers of wood or plastic was used to help keep the materials from warping over time. On the Custom Lap Steel pickups the coil had to be wound off center on the bobbin. The pickups were also wax potted to help eliminate unwanted feedback and added protection to the coil. A small piece of fibre or cardboard was usually placed over the eyelet’s so they didn’t short out with the metal case of the pickup.

Strings above the Pickup
Champion Lap Steel 7,633 Turns 43 PE Telecaster style pickup
Stringmaster 8 String 8,535 Turns 42 PE Similar to a Duosonic

Stringmaster 6 String
7,885 Turns 42 HF Similar to a Duosonic

The Stringmaster pickup assembly used two pickups each wound and magnetized opposite of the other. The pickups are connected to a potentiometer to blend one pickup in and out for single to a dual humbucking sound. Over the years many Champion lap steel pickups were removed and modified to fit the bridge position on Telecasters.

329. What kind of coil wire is used on a Fender pickup?
Most all Fender single coil pickups use 42 Plain Enamel, 43 Plain Enamel and 42 Formvar. I’ve seen coils with really low DC resistance and the tolerance and specifications could be closer to 41 AWG. AWG is the American Wire Gauge that sets the standards for magnet wire specifications. The Plain Enamel and Formvar are insulation’s are baked on the surface of the bare copper magnet wire. The insulation’s can have Minimal, Nominal and Maximum specifications which can affect the size and inductance of the coil being wound. The bare magnet wire can also have Minimal, Nominal and Maximum specifications. A Minimal diameter magnet wire for a specific grade will have higher DC resistance for a given length than a Maximum diameter magnet wire.

330. What part of a Fender coil is grounded?
Normally the beginning of the coil or black wire is grounded to the guitar circuit. On Jaguar pickups the beginning wire is soldered to the metal claw that surrounds the pickup. The beginning wire on a Telecaster bridge pickup also has the beginning black wire connected to the ferrous elevator plate which in turn grounds all the strings and bridge plate by means of the ferrous height adjust screws. If the ferrous elevator plate is removed, the bridge unit and strings are not grounded and can cause the instrument to have increased buzz from electrical interference. I’ve seen Jazz Bass’s where the ground wire was connected to the finish eyelet or the outer turns in the coil. Having the hot beginning of the coil in contact with the pole pieces will cause increased noise in the pickup if accidentally touched. Jazz Bass pickups often put and layer of 1/2” masking tape to insulate the coil from the magnets. In Mustang guitars, the electrical polarity can be reversed by the slide switches and solid top covers prevent accidental touching of the exposed pole pieces.

331. What were the pickup differences between early Fender and CBS pickups?
I find several things that make the early Fenders different from the CBS pickups made after 1965.
The early Fender pickups had much more hand work and unique sounds. The bobbin was mostly black Vulcanized fibre flatwork. The magnets were a larger diameter (.197”) and the CBS pickups used a (.187”) diameter magnet. The magnets were hand ground on one end to help with bobbin assembly. The larger magnets had a rougher sand cast surface that held the bobbin firmly. The early coils were hand wound and CBS coils were wound several at a time. The early bobbins used a wax with lamp black to help eliminate unwanted feedback. Some of the mid-60’s Telecaster bridge pickup were not wax potted, which caused a high amount of microphonic feedback especially when playing at higher volumes. Leo told me, “by hand winding pickups, you can feel the winding tension better between your fingers” and Leo liked hand winding for the tone he wanted out of his pickups.

332. Why are pickups slanted on Fender guitars?
The bridge pickups on Telecaster’s and Stratocaster’s pickups are slanted to expand the range of the pickup. The treble strings will have more bite and the bass strings will have more depth. The bridge pickup usually lacks output and fullness as compared to the neck or middle pickups. Slanting the bridge pickup gave it a little wider tonal range.

333. Why are some Fender covers made with holes and others without, as used on Duosonics and Mustangs?
The cover is basically a component that protects the coil and especially helps keep the string from getting snagged under the lip of the pickup. The Duosonic and Mustang have basic single coil pickups using .625” length rod magnets. The pole pieces are flush with the top of the pickup so there is no need to have a cover with holes. The solid top cover is important for Mustang guitars because the switching circuit could reverse the electrical phasing of the coils. When reversing the lead wires, the pole pieces will buzz if touched. The solid cover eliminates accidental touching of the pole pieces. Also the solid covers help keep moisture from penetrating down into the coil which could eventually cause ICPC within the inner coil. ICPC is “Inner Coil Pole Corrosion” which I have found can cause perfect looking pickups to fail. ICPC is caused when moisture rusts the magnet at the coil beginning and breaks down the insulation on the magnet wire eventually causing the coil to fail.

334. Why do Fender Precision Bass pickups have two offset coils?
The first models of Fender Precision Bass pickups used a single coil pickup very similar looking from the top as a Telecaster bridge pickup but with only 4 rod pole pieces. It seemed that during the mid 50’s several major guitar companies were coming out with humbucking pickups such as Seth E. Lover with the Gibson “Patent Applied For” humbucker, Ray Butts and the Gretsch Filtertron pickup and Leo Fender with the split Precision Bass Pickup. Leo’s split pickup was made with one coil magnetized South and the other coil magnetized North. One coil was wound Clockwise and the other wound Counter-Clockwise with both coils were hooked up in series to each other. The combination of opposite magnetic fields and coil direction produced a humbucking effect. The split pickup were off set to widen the tonal range for deep low bass to bright treble. Each string used a double pole to reduce the unwanted “beat” effect common in pickups with single magnets.

335. Why did the Fender Jaguar have a metal claw around the cover?
The Jaguar claw helped keep the magnet field in closer proximity to the coil which helped make the coil sound louder and brighter. It also helped reduce unwanted electrical interference from entering the coil.

336. Why do some older Strats have a fuller sound than new ones?
If you ever look at the early Stratocasters you can see the coils are wound quite full when wound with 42 Formvar. The coils on the pickups are wound by hand as the insulated magnet wire is guided back and forth on the bobbin. Hand winding can make for fatter coils as each turn is not precisely layered side by side and often the turns over lap which can cause a fatter coil. Automatic winding machines layer the turns side by side as determined by the pitch or how many turns per layer. The older hand wound coils used a pretty basic winding machine. The counter was activated by the use of rubber-bands which could slip and not give the winder an accurate number of turns. The shape of the coil was determined by eye and the hills and valleys would be filled in as needed. Automatic winding will automatically wind the coil to the desired turns per layer and number of layers. Post-CBS Stratocasters started using 42 Plain Enamel and wound precisely to the number of turns on the counter.

337. Why does a Fender Stratocaster have three pickups?
To give the instrument a wider tonal variation. The three pickups give the Stratocaster an added tone with the use of the center pickup. The neck and middle pickups have a treble cut control and the bridge pickup has no tone adjustment. With later modifications the bridge pickup could be rewired at the lever switch to allow tone adjustment. Also, the addition of a five way lever switch allowed the neck and middle pickup along with the middle and bridge pickup to be combined in parallel in the 2 & 4 switch position. The pickups are “in phase” in that position if they are correctly wound and have the correct magnetic polarity.

338. Why are the older Strat pickups staggered and the newer ones flat?
Fender was trying to obtain a better string balance between poles. Having the pole pieces at different lengths would increase or lower the amount of magnetic field to the string. The core of the wound strings had less attraction and the pole pieces were slightly longer. The E & B strings had a larger outside diameter than the wound strings and the pole pieces were shorter. The magnets are in the pickups to magnetize the strings. As the strings move back and forth when plucked, an alternating current is generated and sent through the controls for volume and tone adjustment. Having less components in a model keeps production costs down and reduces the cost of each pole piece. It also allows for less inventory of several components.

339. Has Gibson changed their pickup design on humbuckers?
Over the years there have been design changes due to various reasons. In time, the injection mold can wear out and leave the bobbin out of specifications or excess plastic or flashing on the edges that can cause problems when winding. New designs are created to ease in winding and manufacturing. After the “Patent Applied For” bobbin was discontinued during the mid 60’s a new “T” top bobbin was introduced. The recessed square hole was eliminated because a newer procedure was used for hooking up the black and white lead wires to the coil. Various changes often happen when using various suppliers with their many sources. Even though changes may take place I feel Gibson has always kept a high standard of quality.

340. How can I tell if I have a newer or older type Gibson pickup?
This can be quite involved if you’re not an experienced collector or have knowledge with regards to the history of various models. There have been many changes throughout the history of Gibson pickups. There are many styles and models of Gibson pickups and I would suggest having an experienced collector look at your instrument. I’ve often looked at photos, but it is hard to determine the type of plastics and the particular injection mold or fabricated tooling marks from a photo without specific detail. I would need to have the pickup in hand to fully examine, spec and give a time line. As long as the pickups are stock in an instrument other means can be used to determine the age of a pickup. The serial number and model of an instrument, the date source codes used on the volume and tone potentiometers.

341. How many parts make up various Gibson pickups?
Here is a brief list of the parts that make up a few models of pickups.
Gibson Humbucker: Traditional
- Bottom plate is used to support all the components of the pickup.
- Adjustable bobbin is the screw side.
- Non-adjustable bobbin is the stud side.
- Bar magnet of a desired material for specific pickup model.
- 6 adjustable pole pieces used in the adjustable bobbin for minor string balance.
- 6 studs used in the non-adjustable bobbin.
- Metal spacer to conduct magnetic field to adjustable pole pieces.
- Cover is used for maximum shielding and bobbin protection.
- Hookup wire connected to the fine magnet wire to give better connections.
- Tape is used to protect the coils and secure hookup wires.
- Magnet wire of various sizes for particular sound and output desired.
- Shielded or 4-conductor cable that connects to the controls.
- 4 screws to hold bobbins secure to the bottom plate.
- Wood or plastic shim to keep the bobbins level.
Gibson P-90: Commonly called a “Soapbar” pickup
- 6 adjustable pole pieces for minor string balance.
- Bobbin that is wound as a single coil.
- 2 Bar magnets with like polarities facing each other.
- Bottom plate to hold components secure. Can be “soapbar or dog-ear”
- 2 wood screws to hold magnets and bobbin secure.
- Metal spacer to conduct magnetic field to adjustable pole pieces.
- Hookup wire to connected to the fine magnet wire from the coil.
- Tape to protect the coil and secure the hookup wires.
- Plastic or metal cover to protect the fragile bobbin from abuse or wear.
Shielded hookup wire connected to a solder lug on the bottom side of pickup.

342. When my toggle switch is in the center position and the volume is turned down on either the neck or bridge pickup, the output from my Gibson cuts off.
This is typical on Gibson’s using two pickups. Normally, it can be eliminated by reversing the two wires that are connected to the # 2 & # 3 lugs on each volume potentiometer. This will allow independent volume for both the neck and bridge pickup when the toggle switch is in the center position.

343. What are the slugs used in my Gibson humbucker? Are they ferrous?
The slugs or studs as they are commonly called are made from a soft iron and are used to conduct the magnetic field from the bar magnet to the strings. The studs are 3/16” in diameter and are pressed into the non-adjustable bobbin often concealed by a pickup cover. The corners of the studs have a slight chamfer for ease in assembly as they are pressed into the bobbin. The studs are normally flush or flat with the top of the bobbin and extend out from the bottom of the bobbin. They usually extend the thickness of the bar magnet and conduct the desired magnet polarity to the strings.

344. What are the sound differences between-double creme, double black, zebra?
The sound difference depends on many factors when the coils are wound. There can be different tolerances in the plastics such as creme or black and the space needed for winding the coil. I find that the tolerances in the bare magnet wire diameter, insulation thickness, number of turns, winding tension, hookup wire, magnet tolerance and grade, magnet gauss, pickup position, pickup height, type instrument and wood, tolerances in the volume and tone controls, capacitance in the guitar cord are some of the many combinations which make each pickup sound different. I’ve heard great sounding guitars with double black, zebra and double creme bobbins. Maybe they saw Jeff Beck with exposed double creme bobbins and figured it would make them sound like him. The color of the bobbins was determined by the lack of, or shortage of a particular color. When the molder ran out of black to finish a run of bobbins, they called Seth Lover and asked, “can we run the bobbin in creme” and Seth said “go ahead”. The sound of a pickup is very subjective to each individual.

345. What are the tool marks and numbers on various Gibson bobbins?
When you rewind an early Gibson humbucking bobbin, you will see various numbers inside each one. Both adjustable and non-adjustable bobbins have a mold number to identify parts if they become irregular and it’s easy to determine what mold cavity needs repair. On Gibson “T” top bobbins the numbers can be seen on the top of the bobbin instead of the inside wall on earlier bobbins. Cosmetically the pickup didn’t look as nice as the Patent Applied For bobbins but since the pickup came with a cover it didn’t matter.

346. What does the "T" stand for?
On the second version of the humbucker bobbin, I always thought there was some special thought behind the embossed “T”. The second version has two sharp inside walls and rounded outside walls and the bobbin could be easily be wound top left or top right on a coil machine. When I asked Seth Lover who invented the humbucker what the “T” stood for he laughed and said, “it stands for the “Top” of the bobbin”. This would keep the winder from putting the bobbin on machine backwards and winding the coil in the wrong direction. If a bobbin was wound wrong and assembled with another the pickup would be out of phase with itself or in combination with others.

347. What is the history of the Charlie Christian pickup? The ES-150, EH-150 and other custom pickups?
I have general information about the ES-150 Gibson pickup nick-named “The Charlie Christian” pickup. There are several models with different specifications that I am currently researching. There are bobbins fabricated in different shapes, different blades, various cobalt steel magnets used and several coil specifications to be evaluated. The ES (Electric Spanish) models and EH (Electric Hawaiian) models along with Mandolins and custom instruments use the same style of pickup.

348. What are the magnet strengths of various Gibson pickups?
Gibson uses several grades of magnets made of various materials and when magnetized will have a specified strength. Over time the strength of a magnet can change that can be caused by several factors. Other magnet fields can affect the strength and orientation of a magnet. Electrical interference can change the strength and orientation of a magnet. So many pickups have different magnetic fields even within the same pickup model.

349. What kind of wire is used on a Gibson pickup?
The majority of magnet wire used on Gibson pickups is 42 AWG. AWG is the American Wire Gauge or standards used in measuring the diameter of magnet wire. Magnet wire is made from bare copper wire and insulated to keep the turns from shorting out with each other. Mostly all the early and vintage pickups use a minimal, nominal or maximum thickness of plain enamel insulation. Over time, elements can cause the insulation to break down and cause the coil to become defective. Throughout the history of Gibson, several gauges of magnet wire and insulation’s have been used on guitar, bass, steel guitar and custom instruments.

350. Why are the Gibson slugs non adjustable?
It was the basic design given to the pickup when first designed by Seth Lover in the mid 50s. Originally the pickup was designed without adjustable pole pieces and a row of six pole pieces were added as a “selling point” to enhance sales since the P-90 had adjustable pole pieces.
Traditionally under a cover, the concealed studs are used to conduct the magnetic field to the strings. Gibson traditionally used one row of adjustment screws to give minimal balance to the strings. The stud side has a stronger magnetic field than the adjustable side. With adjustable pole pieces a small amount of magnetic field is directed out the bottom of the pickup.